# API changelog

This page documents changes to the Zulip Server API over time. See
also the [Zulip release lifecycle][release-lifecycle] for background
on why this API changelog is important, and the [Zulip server
changelog][server-changelog].

The API feature levels system used in this changelog is designed to
make it possible to write API clients, such as the Zulip mobile and
terminal apps, that work with a wide range of Zulip server
versions. Every change to the Zulip API is recorded briefly here and
with full details in **Changes** entries in the API documentation for
the modified endpoint(s).

When using an API endpoint whose behavior has changed, Zulip API
clients should check the `zulip_feature_level` field, present in the
[`GET /server_settings`](/api/get-server-settings) and [`POST
/register`](/api/register-queue) responses, to determine the API
format used by the Zulip server that they are interacting with.

## Changes in Zulip 8.0

**Feature level 189**

* [`PATCH /realm/user_settings_defaults`](/api/update-realm-user-settings-defaults),
  [`POST /register`](/api/register-queue), [`PATCH /settings`](/api/update-settings):
  Added new boolean user settings  `enable_followed_topic_email_notifications`,
  `enable_followed_topic_push_notifications`,
  `enable_followed_topic_wildcard_mentions_notify`,
  `enable_followed_topic_desktop_notifications`
  and `enable_followed_topic_audible_notifications` to control whether a user
  receives email, push, wildcard mention, visual desktop and audible desktop
  notifications, respectively, for messages sent to followed topics.

**Feature level 188**

* [`POST /users/me/muted_users/{muted_user_id}`](/api/mute-user),
  [`DELETE /users/me/muted_users/{muted_user_id}`](/api/unmute-user):
  Added support to mute/unmute bot users.

Feature levels 186-187 are reserved for future use in 7.x maintenance
releases.

## Changes in Zulip 7.0

**Feature level 185**

No changes; feature level used for Zulip 7.0 release.

**Feature level 184**

* [`PATCH /scheduled_messages/<int:scheduled_message_id>`](/api/update-scheduled-message):
  Added new endpoint for editing an existing scheduled message.
* [`POST /scheduled_messages`](/api/create-scheduled-message):
  Removed optional `scheduled_message_id` parameter, which had
  been a previous way for clients to support editing an existing
  scheduled message.

**Feature level 183**

* [`POST /register`](/api/register-queue): Removed the
  `realm_community_topic_editing_limit_seconds` property, which was no
  longer in use. The time limit for editing topics is controlled by the
  realm setting `move_messages_within_stream_limit_seconds`, see feature
  level 162.
* [`GET /events`](/api/get-events): Removed the `community_topic_editing_limit_seconds`
  property from realm `update_dict` event documentation, because it was
  never returned as a changed property in this event and was only ever
  returned in the [`POST /register`](/api/register-queue) response.

**Feature level 182**

* `POST /export/realm`: This endpoint now returns the ID of the data
  export object created by the request.

**Feature level 181**

* [`GET /scheduled_messages`](/api/get-scheduled-messages), [`GET
  /events`](/api/get-events), [`POST /register`](/api/register-queue):
  Added `failed` boolean field to scheduled message objects to
  indicate if the server tried to send the scheduled message and was
  unsuccessful. Clients that support unscheduling and editing
  scheduled messages should use this field to indicate to the user
  when a scheduled message failed to send at the appointed time.

**Feature level 180**

* `POST /invites`: Added support for invitations specifying the empty
  list as the user's initial stream subscriptions. Previously, this
  returned an error. This change was also backported to Zulip 6.2, and
  is available at feature levels 157-158 as well.

**Feature level 179**

* [`POST /scheduled_messages`](/api/create-scheduled-message):
  Added new endpoint to create and edit scheduled messages.
* [`GET /events`](/api/get-events):
  Added `scheduled_messages` events sent to clients when a user creates,
  edits or deletes scheduled messages.
* [`POST /register`](/api/register-queue):
  Added an optional `scheduled_messages` field to that includes all
  of the undelivered scheduled messages for the current user.

**Feature level 178**

* `POST users/me/presence`,
  [`GET /users/<user_id_or_email>/presence`](/api/get-user-presence),
  [`GET /realm/presence`](/api/get-presence),
  [`POST /register`](/api/register-queue),
  [`GET /events`](/api/get-events):
  The server no longer stores which client submitted presence data,
  and presence responses from the server will always contain the
  `"aggregated"` and `"website"` keys.

**Feature level 177**

* [`GET /messages`](/api/get-messages),
  [`GET /messages/matches_narrow`](/api/check-messages-match-narrow),
  [`POST /message/flags/narrow`](/api/update-message-flags-for-narrow),
  [`POST /register`](/api/register-queue):
  Added support for three [search/narrow filters](/api/construct-narrow)
  related to direct messages: `is:dm`, `dm` and `dm-including`.
  The `dm` operator replaces and deprecates the `pm-with` operator.
  The `is:dm` filter replaces and deprecates the `is:private` filter.
  The `dm-including` operator replaces and deprecates the `group-pm-with`
  operator. Because existing Zulip messages may have links with these
  legacy filters, they are still supported for backwards-compatibility.

**Feature level 176**

* [`POST /realm/filters`](/api/add-linkifier),
  [`PATCH realm/filters/<int:filter_id>`](/api/update-linkifier):
  The `url_format_string` parameter is replaced by `url_template`.
  [Linkifiers](/help/add-a-custom-linkifier) now only accept
  [RFC 6570][rfc6570] compliant URL templates. The old URL format
  strings are no longer supported.
* [`GET /events`](/api/get-events), [`POST /register`](/api/register-queue):
  The `url_format_string` key in `realm_linkifiers` objects is replaced
  by `url_template`. For backwards-compatibility, clients that do not
  support the `linkifier_url_template`
  [client capability](/api/register-queue#parameter-client_capabilities)
  will receive an empty `realm_linkifiers` array in the `/register`
  response and not receive `realm_linkifiers` events. Unconditionally,
  the deprecated `realm_filters` event type returns an empty array in
  the `/register` response and these events are no longer sent to
  clients.

**Feature level 175**

* [`POST /register`](/api/register-queue), [`PATCH /settings`](/api/update-settings),
  [`PATCH /realm/user_settings_defaults`](/api/update-realm-user-settings-defaults):
  Added new user setting `web_mark_read_on_scroll_policy`. Clients may use this to
  determine the user's preference on whether to mark messages as read or not when
  scrolling through their message feed.

**Feature level 174**:

* [`POST /typing`](/api/set-typing-status), [`POST /messages`](/api/send-message):
  Added `"direct"` as the preferred way to indicate a direct message for the
  `type` parameter, deprecating the original `"private"`. While `"private"`
  is still supported for direct messages, clients are encouraged to use
  the modern convention with servers that support it, because support for
  `"private"` may eventually be removed.

**Feature level 173**:

* [`GET /scheduled_messages`](/api/get-scheduled-messages), [`DELETE
  /scheduled_messages/<int:scheduled_message_id>`](/api/delete-scheduled-message):
  Added new endpoints to fetch and delete scheduled messages.

**Feature level 172**

* [`PATCH /messages/{message_id}`](/api/update-message):
  [Topic editing restrictions](/help/restrict-moving-messages) now apply
  to stream messages without a topic.
* [`PATCH /messages/{message_id}`](/api/update-message): When users, other
  than organization administrators and moderators, use
  `"propagate_mode": "change_all"` to move messages that have passed the
  organization's time limit for updating a message's topic and/or stream,
  this endpoint now returns an error response
  (`"code": "MOVE_MESSAGES_TIME_LIMIT_EXCEEDED"`).

**Feature level 171**:

* [`POST /fetch_api_key`](/api/fetch-api-key),
  [`POST /dev_fetch_api_key`](/api/dev-fetch-api-key): The return values
  for these endpoints now include the unique ID of the user who owns the
  API key.

**Feature level 170**

* [`POST /user_topics`](/api/update-user-topic): Added a new endpoint to
  update a user's personal preferences for a topic, which deprecates the
  [`PATCH /users/me/subscriptions/muted_topics`](/api/mute-topic) endpoint.
  The deprecated endpoint is maintained for backwards-compatibility but may be
  removed in a future release.
* [`POST /register`](/api/register-queue), [`GET /events`](/api/get-events):
  Unmuted added as a visibility policy option to the objects sent in response
  to the `user_topic` event.

**Feature level 169**

* [`PATCH /users/me/subscriptions/muted_topics`](/api/mute-topic):
  Trying to mute a topic that is already muted or unmute a topic
  that was not previously muted now results in a success response
  rather than an error.

**Feature level 168**

* [`POST /register`](/api/register-queue), [`PATCH /settings`](/api/update-settings),
  [`PATCH /realm/user_settings_defaults`](/api/update-realm-user-settings-defaults):
  Replaced the boolean user setting `realm_name_in_notifications`
  with an integer `realm_name_in_email_notifications_policy`.

**Feature level 167**

* [All REST API endpoints](/api/rest-error-handling#ignored-parameters):
  Implemented `ignored_parameters_unsupported` as a possible return value
  in the JSON success response for all endpoints. This value is a array
  of any parameters that were sent in the request by the client that are
  not supported by the endpoint. Previously, unsupported parameters were
  silently ignored, except in the subset of endpoints which already
  supported this return value; see feature levels 111, 96 and 78.

**Feature level 166**

* [`POST /messages`](/api/send-message): Eliminated the undocumented
  `realm_str` parameter. This parameter was already redundant due to
  it needing to match the realm of the user making the request, otherwise
  returning an authorization error. With this, the parameter is removed,
  meaning that if provided in the API request, it will be ignored.

**Feature level 165**

* [`PATCH /user_groups/{user_group_id}`](/api/update-user-group): The
  `name` and `description` parameters are now optional.

**Feature level 164**

* [`POST /register`](/api/register-queue): Added the
  `server_presence_ping_interval_seconds` and
  `server_presence_offline_threshold_seconds` fields for clients
  to use when implementing the [presence](/api/get-presence) system.

**Feature level 163**

* [`GET /users`](/api/get-users), [`GET /users/{user_id}`](/api/get-user),
  [`GET /users/{email}`](/api/get-user-by-email),
  [`GET /users/me`](/api/get-own-user), [`GET /events`](/api/get-events):
  The `delivery_email` field is always present in user objects, including
  the case when a user's `email_address_visibility` is set to everyone.
  The value will be `null` if the requester does not have access to the
  user's real email. For bot users, the `delivery_email` field is always
  set to the bot user's real email.
* [`GET /events`](/api/get-events): Event for updating a user's
  `delivery_email` is now sent to all users who have access to it, and
  is also sent when a user's `email_address_visibility` setting changes.
* [`GET /events`](/api/get-events), [`POST /register`](/api/register-queue)
  [`GET /users`](/api/get-users), [`GET /users/{user_id}`](/api/get-user),
  [`GET /users/{email}`](/api/get-user-by-email),
  [`GET /users/me`](/api/get-own-user), [`GET /messages`](/api/get-messages),
  [`GET /messages/{message_id}`](/api/get-message): Whether the `avatar_url`
  field in message and user objects returned by these endpoints can be `null`
  now depends on if the current user has access to the other user's real
  email address based on the other user's `email_address_visibility` policy.
* [`POST /register`](/api/register-queue), [`PATCH /settings`](/api/update-settings),
  [`PATCH /realm/user_settings_defaults`](/api/update-realm-user-settings-defaults):
  Added user setting `email_address_visibility`, to replace the
  realm setting `email_address_visibility`.
* [`POST /register`](/api/register-queue), `PATCH /realm`: Removed realm
  setting `email_address_visibility`.

**Feature level 162**

* `PATCH /realm`, [`POST /register`](/api/register-queue),
   [`GET /events`](/api/get-events): Added two new realm settings
  `move_messages_within_stream_limit_seconds` and
  `move_messages_between_streams_limit_seconds` for organizations to
  configure time limits for editing topics and moving messages between streams.
* [`PATCH /messages/{message_id}`](/api/update-message): For users other than
  administrators and moderators, the time limit for editing topics is now
  controlled via the realm setting `move_messages_within_stream_limit_seconds`
  and the time limit for moving messages between streams is now controlled by
  the realm setting `move_messages_between_streams_limit_seconds`.

**Feature level 161**

* [`POST /users/me/subscriptions`](/api/subscribe),
  [`PATCH /streams/{stream_id}`](/api/update-stream): Added
  `can_remove_subscribers_group_id` parameter to support setting and
  changing the user group whose members can remove other subscribers
  from the specified stream.
* [`DELETE /users/me/subscriptions`](/api/unsubscribe): Expanded the
  situations where users can use this endpoint to unsubscribe other
  users from a stream to include the case where the current user has
  access to the stream and is a member of the user group specified by
  the `can_remove_subscribers_group_id` for the stream.

**Feature level 160**

* `POST /api/v1/jwt/fetch_api_key`: Added new endpoint to fetch API
  keys using JSON Web Token (JWT) authentication.
* `accounts/login/jwt/`: Adjusted format of requests to undocumented,
  optional endpoint for JWT authentication log in support.

**Feature level 159**

* `PATCH /realm`, [`POST /register`](/api/register-queue),
  [`GET /events`](/api/get-events):
  Nobody added as an option for the realm settings `edit_topic_policy`
  and `move_messages_between_streams_policy`.
* [`PATCH /messages/{message_id}`](/api/update-message): Permission
  to edit the stream and/or topic of messages no longer depends on the
  realm setting `allow_message_editing`.
* [`PATCH /messages/{message_id}`](/api/update-message): The user who
  sent the message can no longer edit the message's topic indefinitely.

Feature level 158 is reserved for future use in 6.x maintenance
releases.

## Changes in Zulip 6.2

**Feature level 157**

* `POST /invites`: Added support for invitations specifying the empty
  list as the user's initial stream subscriptions. Previously, this
  returned an error. This change was backported from the Zulip 7.0
  branch, and thus is available at feature levels 157-158 and 180+.

## Changes in Zulip 6.0

**Feature level 156**

No changes; feature level used for Zulip 6.0 release.

**Feature level 155**

* [`GET /messages`](/api/get-messages): The new `include_anchor`
  parameter controls whether a message with ID matching the specified
  `anchor` should be included.
* The `update_message_flags` event sent by [`POST
  /messages/flags`](/api/update-message-flags) no longer redundantly
  lists messages where the flag was set to the same state it was
  already in.
* [`POST /messages/flags/narrow`](/api/update-message-flags-for-narrow):
  This new endpoint allows updating message flags on a range of
  messages within a narrow.

**Feature level 154**

* [`POST /streams/{stream_id}/delete_topic`](/api/delete-topic):
  When the process of deleting messages times out, a success response
  with "partially_completed" result will now be returned by the server,
  analogically to the `/mark_all_as_read` endpoint.

**Feature level 153**

* [`POST /mark_all_as_read`](/api/mark-all-as-read): Messages are now
  marked as read in batches, so that progress will be made even if the
  request times out because of an extremely large number of unread
  messages to process. Upon timeout, a success response with a
  "partially_completed" result will be returned by the server.

**Feature level 152**

* [`PATCH /messages/{message_id}`](/api/update-message): The
  `send_notification_to_old_thread` and
  `send_notification_to_new_thread` parameters are now respected when
  moving a topic within a stream. The default value for
  `send_notification_to_old_thread` was changed from `true` to
  `false`.

**Feature level 151**

* [`POST /register`](/api/register-queue), [`GET /events`](/api/get-events),
  [`POST /realm/profile_fields`](/api/create-custom-profile-field),
  [`GET /realm/profile_fields`](/api/get-custom-profile-fields): Added
  pronouns custom profile field type.

**Feature level 150**

* [`GET /events`](/api/get-events): Separate events are now sent on changing
  `allow_message_editing`, `message_content_edit_limit_seconds` and
  `edit_topic_policy` settings, whereas previously one event was sent including
  all of these setting values irrespective of which of them were actually changed.
* `PATCH /realm`: Only changed settings are included in the response data now
  when changing `allow_message_editing`, `edit_topic_policy` and
  `message_content_edit_limit_seconds` settings, instead of including all the
  fields even if one of these settings was changed.

**Feature level 149**

* [`POST /register`](/api/register-queue): The `client_gravatar` and
  `include_subscribers` parameters now return an error for
  [unauthenticated requests](/help/public-access-option) if an
  unsupported value is requested by the client.

**Feature level 148**

* [`POST /users/me/status`](/api/update-status),
  [`POST /register`](/api/register-queue), [`GET /events`](/api/get-events):
  The user status `away` field/parameter is deprecated, and as of this
  feature level are a legacy way to access the user's `presence_enabled`
  setting, with `away = !presence_enabled`. To be removed in a future
  release.

**Feature level 147**

* [`POST /streams/{stream_id}/delete_topic`](/api/delete-topic):
  Messages now are deleted in batches, starting from the newest, so
  that progress will be made even if the request times out because of
  an extremely large topic.

**Feature level 146**

* [`POST /realm/profile_fields`](/api/create-custom-profile-field),
[`GET /realm/profile_fields`](/api/get-custom-profile-fields): Added a
new parameter `display_in_profile_summary`, which clients use to
decide whether to display the field in a small/summary section of the
user's profile.

**Feature level 145**

* [`DELETE users/me/subscriptions`](/api/unsubscribe): Normal users can
  now remove bots that they own from streams.

**Feature level 144**

* [`GET /messages/{message_id}/read_receipts`](/api/get-read-receipts):
  The `user_ids` array returned by the server no longer includes IDs
  of users who have been muted by or have muted the current user.

**Feature level 143**

* `PATCH /realm`: The `disallow_disposable_email_addresses`,
  `emails_restricted_to_domains`, `invite_required`, and
  `waiting_period_threshold` settings can no longer be changed by
  organization administrators who are not owners.
* `PATCH /realm/domains`, `POST /realm/domains`, `DELETE
  /realm/domains`: Organization administrators who are not owners can
  no longer access these endpoints.

**Feature level 142**

* [`GET users/me/subscriptions`](/api/get-subscriptions), [`GET
  /streams`](/api/get-streams), [`POST /register`](/api/register-queue),
  [`GET /events`](/api/get-events): Added `can_remove_subscribers_group_id`
  field to Stream and Subscription objects.

**Feature level 141**

* [`POST /register`](/api/register-queue), [`PATCH
  /settings`](/api/update-settings), [`PATCH
  /realm/user_settings_defaults`](/api/update-realm-user-settings-defaults):
  Added new `user_list_style` display setting, which controls the
  layout of the right sidebar.

**Feature level 140**

* [`POST /register`](/api/register-queue): Added string field `server_emoji_data_url`
  to the response.

**Feature level 139**

* [`GET /get-events`](/api/get-events): When a user mutes or unmutes
  their subscription to a stream, a `subscription` update event
  is now sent for the `is_muted` property and for the deprecated
  `in_home_view` property to support clients fully migrating to use the
  `is_muted` property. Prior to this feature level, only one event was
  sent to clients with the deprecated `in_home_view` property.

**Feature level 138**

* [`POST /register`](/api/register-queue), [`GET
  /events`](/api/get-events): `message_content_edit_limit_seconds`
  now represents no limit using `null`, instead of the integer 0.
* `PATCH /realm`: One now sets `message_content_edit_limit_seconds`
  to no limit by passing the string `unlimited`, rather than the
  integer 0.

**Feature level 137**

* [`GET /messages/{message_id}/read_receipts`](/api/get-read-receipts):
  Added new endpoint to fetch read receipts for a message.
* [`POST /register`](/api/register-queue), [`GET
  /events`](/api/get-events), `PATCH /realm`: Added new
  `enable_read_receipts` realm setting.

**Feature level 136**

* [`PATCH /streams/{stream_id}`](/api/update-stream): The endpoint
  now returns an error for a request to make a public stream with
  protected history which was previously ignored silently.
* [`PATCH /streams/{stream_id}`](/api/update-stream): Added support
  to change access to history of the stream by only passing
  `history_public_to_subscribers` parameter without `is_private`
  and `is_web_public` parameters.

**Feature level 135**

* [`DELETE /user/{user_id}`](/api/deactivate-user): Added
  `deactivation_notification_comment` field controlling whether the
  user receives a notification email about their deactivation.

**Feature level 134**

* [`GET /events`](/api/get-events): Added `user_topic` event type
  which is sent when a topic is muted or unmuted. This generalizes and
  replaces the previous `muted_topics` array, which will no longer be
  sent if `user_topic` was included in `event_types` when registering
  the queue.
* [`POST /register`](/api/register-queue): Added `user_topics` array
  to the response. This generalizes and replaces the previous
  `muted_topics` array, which will no longer be sent if `user_topic`
  is included in `fetch_event_types`.

**Feature level 133**

* [`POST /register`](/api/register-queue), `PATCH /realm`: Removed
  stream administrators option from `wildcard_mention_policy` setting.
* [`POST /register`](/api/register-queue), [`GET /events`](/api/get-events),
  [`GET /users/me/subscriptions`](/api/get-subscriptions): Removed
  `role` field from subscription objects.

**Feature level 132**

* [`GET /streams/{stream_id}`](/api/get-stream-by-id):
  Added new endpoint to get a stream by ID.

**Feature level 131**

* [`GET /user_groups`](/api/get-user-groups),[`POST
  /register`](/api/register-queue): Renamed `subgroups` field in
  the user group objects to `direct_subgroup_ids`.
* [`GET /events`](/api/get-events): Renamed `subgroup_ids` field
  in the group object to `direct_subgroup_ids`.

**Feature level 130**

* `PATCH /bots/{bot_user_id}`: Added support for changing a bot's role
  via this endpoint. Previously, this could only be done via [`PATCH
  /users/{user_id}`](/api/update-user).

**Feature level 129**

* [`POST /register`](/api/register-queue),
  [`GET /events`](/api/get-events), `PATCH /realm`: Added realm setting
  `want_advertise_in_communities_directory` for organizations to give
  permission to be advertised in the Zulip communities directory.

**Feature level 128**

* [`POST /register`](/api/register-queue), [`GET
  /events`](/api/get-events), `PATCH /realm`: Added
  `org_type` realm setting.

**Feature level 127**

* [`GET /user_groups`](/api/get-user-groups),[`POST
  /register`](/api/register-queue): Added `subgroups` field,
  which is a list of IDs of all the subgroups of the user group, to
  user group objects.
* [`GET /events`](/api/get-events): Added new `user_group` events
  operations for live updates to subgroups (`add_subgroups` and
  `remove_subgroups`).
* [`PATCH /user_groups/{user_group_id}/subgroups`](/api/update-user-group-subgroups):
  Added new endpoint for updating subgroups of a user group.
* [`GET /user_groups/{user_group_id}/members/{user_id}`](/api/get-is-user-group-member):
  Added new endpoint for checking whether a given user is member of a
  given user group.
* [`GET /user_groups/{user_group_id}/members`](/api/get-user-group-members):
  Added new endpoint to get members of a user group.
* [`GET /user_groups/{user_group_id}/members`](/api/get-user-group-subgroups):
  Added new endpoint to get subgroups of a user group.

**Feature level 126**

* `POST /invites`, `POST /invites/multiuse`: Replaced `invite_expires_in_days`
  parameter with `invite_expires_in_minutes`.

**Feature level 125**

* [`POST /register`](/api/register-queue), [`PATCH
  /settings`](/api/update-settings), [`PATCH
  /realm/user_settings_defaults`](/api/update-realm-user-settings-defaults):
  Added new `display_emoji_reaction_users` display setting,
  controlling whether to display the names of users with emoji reactions.

Feature levels 123-124 are reserved for future use in 5.x maintenance
releases.

## Changes in Zulip 5.0

**Feature level 122**

No changes; feature level used for Zulip 5.0 release.

**Feature level 121**

* [`GET /events`](/api/get-events): Added `message_details` field
  appearing in message flag update events when marking previously read
  messages as unread.

**Feature level 120**

* [`GET /messages/{message_id}`](/api/get-message): This endpoint
  now sends the full message details. Previously, it only returned
  the message's raw Markdown content.

**Feature level 119**

* [`POST /register`](/api/register-queue): The `unread_msgs` section
  of the response now prefers `other_user_id` over the poorly named
  `sender_id` field in the `pms` dictionaries. This change is
  motivated by the possibility that a message you yourself sent to
  another user could be marked as unread.

**Feature level 118**

* [`GET /messages`](/api/get-messages), [`GET
  /events`](/api/get-events): Improved the format of the
  `edit_history` object within message objects. Entries for stream
  edits now include a both a `prev_stream` and `stream` field to
  indicate the previous and current stream IDs. Prior to this feature
  level, only the `prev_stream` field was present. Entries for topic
  edits now include both a `prev_topic` and `topic` field to indicate
  the previous and current topic, replacing the `prev_subject`
  field. These changes substantially simplify client complexity for
  processing historical message edits.

* [`GET messages/{message_id}/history`](/api/get-message-history):
  Added `stream` field to message history `snapshot` indicating
  the updated stream ID of messages moved to a new stream.

**Feature level 117**

* `POST /invites`, `POST /invites/multiuse`: Added support for passing
  `null` as the `invite_expires_in_days` parameter to request an
  invitation that never expires.

**Feature level 116**

* [`GET /server_settings`](/api/get-server-settings): Added
  `realm_web_public_access_enabled` as a realm-specific server setting,
  which can be used by clients to detect whether the realm allows and
  has at least one [web-public stream](/help/public-access-option).

**Feature level 115**

* Mobile push notifications about stream messages now include the
  `stream_id` field.

**Feature level 114**

* [`GET /events`](/api/get-events): Added `rendering_only` field to
  `update_message` event type to indicate if the message change only
  updated the rendering of the message or if it was the result of a
  user interaction.

* [`GET /events`](/api/get-events): Updated `update_message` event type
  to always include `edit_timestamp` and `user_id` fields. If the event
  only updates the rendering of the message, then the `user_id` field
  will be present, but with a value of null as the update was not the
  result of a user interaction.

**Feature level 113**

* `GET /realm/emoji`, `POST /realm/emoji/{emoji_name}`, [`GET
  /events`](/api/get-events), [`POST /register`](/api/register-queue):
  The `still_url` field for custom emoji objects is now always
  present, with a value of null for non-animated emoji. Previously, it
  only was present for animated emoji.

**Feature level 112**

* [`GET /events`](/api/get-events): Updated `update_message` event type
  to include `stream_id` field for all edits to stream messages.

**Feature level 111**

* [`POST /users/me/subscriptions/properties`](/api/update-subscription-settings):
  Removed `subscription_data` from response object, replacing it with
  `ignored_parameters_unsupported`.

**Feature level 110**

* [`POST /register`](/api/register-queue): Added
  `server_web_public_streams_enabled` to the response.

**Feature level 109**

* [`POST /register`](/api/register-queue), [`GET
  /events`](/api/get-events), `PATCH /realm`: Added new
  `enable_spectator_access` realm setting.

**Feature level 108**

* In the mobile application authentication flow, the authenticated
  user's `user_id` is now included in the parameters encoded in the
  final `zulip://` redirect URL.

**Feature level 107**

* [`POST /register`](/api/register-queue), [`PATCH /settings`](/api/update-settings),
  [`PATCH /realm/user_settings_defaults`](/api/update-realm-user-settings-defaults):
  Added user setting `escape_navigates_to_default_view` to allow users to
  [disable the keyboard shortcut](/help/configure-default-view) for the `Esc` key that
  navigates the app to the default view.

**Feature level 106**

* [`PATCH /user/{user_id}`](/api/update-user): Removed unnecessary JSON-encoding of string
  parameter `full_name`.

**Feature level 105**

* [`POST /register`](/api/register-queue), [`PATCH
  /settings`](/api/update-settings), [`PATCH
  /realm/user_settings_defaults`](/api/update-realm-user-settings-defaults):
  Added three new privacy settings: `send_private_typing_notifications`,
  `send_stream_typing_notifications`, and `send_read_receipts`.

**Feature level 104**

* `PATCH /realm`: Added `string_id` parameter for changing an
  organization's subdomain. Currently, this is only allowed for
  changing a demo organization to a normal one.

**Feature level 103**

* [`POST /register`](/api/register-queue): Added `create_web_public_stream_policy`
  policy for which users can create web-public streams.
* [`GET /events`](/api/get-events), `PATCH /realm`: Added support for updating
  `create_web_public_stream_policy`.
* [`POST /register`](/api/register-queue): Added `can_create_web_public_streams` boolean
  field to the response.

**Feature level 102**

* [`POST /register`](/api/register-queue), `PATCH /realm`: The
  `create_stream_policy` setting was split into two settings for
  different types of streams: `create_private_stream_policy` and
  `create_public_stream_policy`.
* [`POST /register`](/api/register-queue): The `create_stream_policy`
  property was deprecated in favor of the
  `create_private_stream_policy` and `create_public_stream_policy`
  properties, but it still available for backwards-compatibility.

**Feature level 101**

* [`POST /register`](/api/register-queue), `PATCH /realm`: Replaced
  the `allow_message_deleting` boolean field with an integer field
  `delete_own_message_policy` defining which roles can delete messages
  they had sent.

**Feature level 100**

* [`POST /register`](/api/register-queue), [`GET
  /events`](/api/get-events): `message_content_delete_limit_seconds`
  now represents no limit using `null`, instead of the integer 0, and 0 is
  no longer a possible value with any meaning.
* `PATCH /realm`: One now sets `message_content_delete_limit_seconds`
  to no limit by passing the string `unlimited`, rather than the
  integer 0.

**Feature level 99**

* [`PATCH /realm/user_settings_defaults`](/api/update-realm-user-settings-defaults),
  `PATCH /realm`: The `default_twenty_four_hour_time` parameter to
  `PATCH /realm` has been replaced by the `twenty_four_hour_time` parameter
  to `PATCH /realm/user_settings_defaults`, to match the new model for
  user preference defaults settings.

* [`POST /register`](/api/register-queue): Removed `realm_default_twenty_four_hour_time`
  from the response object. This value is now available in the
  `twenty_four_hour_time` field of the `realm_user_settings_default` object.

**Feature level 98**

* [`POST /subscribe`](/api/subscribe): Added `is_web_public` parameter
  for requesting the creation of a web-public stream.
* [`PATCH /streams/{stream_id}`](/api/update-stream): Added
  `is_web_public` parameter for converting a stream into a web-public stream.

**Feature level 97**

* `GET /realm/emoji`, `POST /realm/emoji/{emoji_name}`, [`GET
  /events`](/api/get-events), [`POST /register`](/api/register-queue):
  Custom emoji objects may now contain a `still_url` field, with the
  URL of a PNG still image version of the emoji. This field will only be
  present for animated emoji.

**Feature level 96**

* [`PATCH /realm/user_settings_defaults`](/api/update-realm-user-settings-defaults):
  Added new endpoint to update default values of user settings in a realm.
* `POST /invites`, `POST /invites/multiuse`: Added
  `invite_expires_in_days` parameter encoding the number days before
  the invitation should expire.

**Feature level 95**

* [`POST /register`](/api/register-queue): Added
  `realm_user_settings_defaults` object, containing default values of
  personal user settings for new users in the realm.

* [`GET /events`](/api/get-events): Added
  `realm_user_settings_defaults` event type, which is sent when the
  organization's configured default settings for new users change.

**Feature level 94**

* [`POST /register`](/api/register-queue): Added
  `demo_organization_scheduled_deletion_date` field to realm data.

**Feature level 93**

* [`POST /register`](/api/register-queue), [`GET /user_groups`](/api/get-user-groups),
  [`GET /events`](/api/get-events): Added `is_system_group` field to user group
  objects.

**Feature level 92**

* [`GET /messages`](/api/get-messages), [`POST
  /register`](/api/register-queue), [`GET /users`](/api/get-users),
  [`GET /users/{user_id}`](/api/get-user), [`GET
  /users/{email}`](/api/get-user-by-email): The `client_gravatar`
  parameter now defaults to `true`.

**Feature level 91**

* `PATCH /realm`, [`PATCH /streams/{stream_id}`](/api/update-stream):
  These endpoints now accept `"unlimited"` for `message_retention_days`,
  replacing `"forever"` as the way to encode a retention policy where
  messages are not automatically deleted.

**Feature level 90**

* [`POST /register`](/api/register-queue): The `unread_msgs` section
  of the response no longer includes `sender_ids` in the `streams`
  dictionaries. These were removed because no clients were interested
  in using the data, which required substantial complexity to
  construct correctly.

**Feature level 89**

* [`GET /events`](/api/get-events): Introduced the `user_settings`
  event type, unifying and replacing the previous
  `update_display_settings` and `update_global_notifications` event
  types. The legacy event types are still supported for backwards
  compatibility, but will be removed in a future release.
* [`POST /register`](/api/register-queue): Added `user_settings` field
  in the response, which is a dictionary containing all the user's
  personal settings. For backwards-compatibility, individual settings
  will still appear in the top-level response for clients don't
  support the `user_settings_object` client capability.
* [`POST /register`](/api/register-queue): Added the
  `user_settings_object` property to supported `client_capabilities`.
  When enabled, the server will not include a duplicate copy of
  personal settings in the top-level response.
* [`GET /events`](/api/get-events): `update_display_settings` and
  `update_global_notifications` events now only sent to clients that
  did not include `user_settings_object` in their
  `client_capabilities` when the event queue was created.

**Feature level 88**

* [`POST /register`](/api/register-queue): Added `zulip_merge_base`
  field to the response.
* [`GET /events`](/api/get-events): Added new `zulip_merge_base`
  field to the `restart` event.
* [`GET /server_settings`](/api/get-server-settings): Added
  `zulip_merge_base` to the responses which can be used to
  make "About Zulip" widgets in clients.

**Feature level 87**

* [`PATCH /settings`](/api/update-settings): Added a new
  `enable_drafts_synchronization` setting, which controls whether the
  syncing drafts between different clients is enabled.

* [`GET /events`](/api/get-events), [`POST /register`](/api/register-queue):
  Added new `enable_drafts_synchronization` setting under
  `update_display_settings`.

* [`GET /drafts`](/api/get-drafts): Added new endpoint to fetch user's
  synced drafts from the server.

* [`POST /drafts`](/api/create-drafts): Added new endpoint to create
  drafts when syncing has been enabled.

* [`PATCH /drafts/{draft_id}`](/api/edit-draft): Added new endpoint
  to edit a draft already owned by the user.

* [`DELETE /drafts/{draft_id}`](/api/delete-draft): Added new endpoint
  to delete a draft already owned by the user.

**Feature level 86**

* [`GET /events`](/api/get-events): Added `emoji_name`,
  `emoji_code`, and `reaction_type` fields to `user_status` objects.
* [`POST /register`](/api/register-queue): Added `emoji_name`,
  `emoji_code`, and `reaction_type` fields to `user_status` objects.
* [`POST /users/me/status`](/api/update-status): Added support for new
  `emoji_name`, `emoji_code`, and `reaction_type` parameters.

**Feature level 85**

* [`POST /register`](/api/register-queue), `PATCH /realm`: Replaced `add_emoji_by_admins_only`
  field with an integer field `add_custom_emoji_policy`.

**Feature level 84**

* [`POST /register`](/api/register-queue): The `enter_sends` setting
  is now sent when `update_display_setting` is present in
  `fetch_event_types` instead of `realm_user`.

**Feature level 83**

* * [`POST /register`](/api/register-queue): The `cross_realm_bots`
  section of the response now uses the `is_system_bot` flag to
  indicate whether the bot is a system bot.

**Feature level 82**

* [`PATCH /settings`](/api/update-settings) now accepts a new
  `email_notifications_batching_period_seconds` field for setting the
  time duration for which the server will collect email notifications
  before sending them.

**Feature level 81**

* `POST /users/me/enter-sends` has been removed. The `enter_sends`
  setting is now edited using the normal [`PATCH
  /settings`](/api/update-settings) endpoint.

**Feature level 80**

* [`PATCH /settings`](/api/update-settings): The
  `/settings/notifications` and `/settings/display` endpoints were
  merged into the main `/settings` endpoint; now all personal settings
  should be edited using that single endpoint. The old URLs are
  preserved as deprecated aliases for backwards compatibility.

**Feature level 79**

* [`GET /users/me/subscriptions`](/api/get-subscriptions): The
  `subscribers` field now returns user IDs if `include_subscribers` is
  passed. Previously, this endpoint returned user display email
  addresses in this field.
* `GET /streams/{stream_id}/members`: This endpoint now returns user
  IDs. Previously, it returned display email addresses.

**Feature level 78**

* [`PATCH /settings`](/api/update-settings): Added
  `ignored_parameters_unsupported` field, which is a list of
  parameters that were ignored by the endpoint, to the response
  object.

* [`PATCH /settings`](/api/update-settings): Removed `full_name` and
  `account_email` fields from the response object.

**Feature level 77**

* [`GET /events`](/api/get-events): Removed `recipient_id` and
  `sender_id` field in responses of `delete_message` event when
  `message_type` is `private`.

**Feature level 76**

* [`POST /fetch_api_key`](/api/fetch-api-key), [`POST
  /dev_fetch_api_key`](/api/dev-fetch-api-key): The HTTP status for
  authentication errors is now 401. This was previously 403.
* All API endpoints now use the HTTP 401 error status for API requests
  involving a deactivated user or realm. This was previously 403.
* Mobile push notifications now include the `mentioned_user_group_id`
  and `mentioned_user_group_name` fields when a user group containing
  the user is mentioned.  Previously, these were indistinguishable
  from personal mentions (as both types have `trigger="mention"`).

**Feature level 75**

* [`POST /register`](/api/register-queue), `PATCH /realm`: Replaced `allow_community_topic_editing`
  field with an integer field `edit_topic_policy`.

**Feature level 74**

* [`POST /register`](/api/register-queue): Added `server_needs_upgrade`
  and `event_queue_longpoll_timeout_seconds` field when fetching
  realm data.

**Feature level 73**

* [`GET /users`](/api/get-users), [`GET /users/{user_id}`](/api/get-user),
  [`GET /users/{email}`](/api/get-user-by-email) and
  [`GET /users/me`](/api/get-own-user): Added is `user_billing_admin` field to
  returned user objects.
* [`GET /events`](/api/get-events): Added `is_billing_admin` field to
  user objects sent in `realm_user` events.
* [`POST /register`](/api/register-queue): Added `is_billing_admin` field
  in the user objects returned in the `realm_users` field.

**Feature level 72**

* [`POST /register`](/api/register-queue): Renamed `max_icon_file_size` to
  `max_icon_file_size_mib`, `realm_upload_quota` to `realm_upload_quota_mib`
  and `max_logo_file_size` to `max_logo_file_size_mib`.

**Feature level 71**

* [`GET /events`](/api/get-events): Added `is_web_public` field to
  `stream` events changing `invite_only`.

**Feature level 70**

* [`POST /register`](/api/register-queue): Added new top-level
  `server_timestamp` field when fetching presence data, to match the
  existing presence API.

Feature levels 66-69 are reserved for future use in 4.x maintenance
releases.

## Changes in Zulip 4.0

**Feature level 65**

No changes; feature level used for Zulip 4.0 release.

**Feature level 64**

* `PATCH /streams/{stream_id}`: Removed unnecessary JSON-encoding of string
  parameters `new_name` and `description`.
* `PATCH /settings/display`: Removed unnecessary JSON-encoding of string
  parameters `default_view`, `emojiset` and `timezone`.

**Feature level 63**

* `PATCH /settings/notifications`: Removed unnecessary JSON-encoding of string
  parameter `notification_sound`.
* `PATCH /settings/display`: Removed unnecessary JSON-encoding of string
  parameter `default_language`.
* `POST /users/me/tutorial_status`: Removed unnecessary JSON-encoding of string
  parameter `status`.
* `POST /realm/domains`: Removed unnecessary JSON-encoding of string
  parameter `domain`.
* `PATCH /default_stream_groups/{user_id}`: Removed unnecessary JSON-encoding of string
  parameters `new_group_name` and `new_description`.
* `POST /users/me/hotspots`: Removed unnecessary JSON-encoding of string
  parameter `hotspot`.

**Feature level 62**

* Added `moderators only` option for `wildcard_mention_policy`.

**Feature level 61**

* `POST /invites`, `POST /invites/multiuse`: Added support for
  inviting users as moderators.

**Feature level 60**

* [`POST /register`](/api/register-queue): Added a new boolean field
  `is_moderator`, similar to the existing `is_admin`, `is_owner` and
  `is_guest` fields, to the response.
* [`PATCH /users/{user_id}`](/api/update-user): Added support for
  changing a user's organization-level role to moderator.
* API endpoints that return `role` values can now return `300`, the
  encoding of the moderator role.

**Feature level 59**

* [`GET /users`](/api/get-users), [`GET /users/{user_id}`](/api/get-user),
  [`GET /users/{email}`](/api/get-user-by-email) and
  [`GET /users/me`](/api/get-own-user): Added `role` field to returned
  user objects.
* [`GET /events`](/api/get-events): Added `role` field to
  user objects sent in `realm_user` events.
* [`POST /register`](/api/register-queue): Added `role` field
  in the user objects returned in the `realm_users` field.
* [`GET /events`](/api/get-events): Added new `zulip_version` and
  `zulip_feature_level` fields to the `restart` event.

**Feature level 58**

* [`POST /register`](/api/register-queue): Added the new
  `stream_typing_notifications` property to supported
  `client_capabilities`.
* [`GET /events`](/api/get-events): Extended format for `typing`
  events to support typing notifications in stream messages. These new
  events are only sent to clients with `client_capabilities`
  showing support for `stream_typing_notifications`.
* [`POST /set-typing-status`](/api/set-typing-status): Added support
  for sending typing notifications for stream messages.

**Feature level 57**

* [`PATCH /realm/filters/{filter_id}`](/api/update-linkifier): New
  endpoint added to update a realm linkifier.

**Feature level 56**

* [`POST /register`](/api/register-queue): Added a new setting
  `move_messages_between_streams_policy` for controlling who can
  move messages between streams.

**Feature level 55**

* [`POST /register`](/api/register-queue): Added `realm_giphy_rating`
  and `giphy_rating_options` fields.
* `PATCH /realm`: Added `giphy_rating` parameter.

**Feature level 54**

* `GET /realm/filters` has been removed and replace with [`GET
  /realm/linkifiers`](/api/get-linkifiers) which returns the data in a
  cleaner dictionary format.
* [`GET /events`](/api/get-events): Introduced new event type
  `realm_linkifiers`.  The previous `realm_filters` event type is
  still supported for backwards compatibility, but will be removed in
  a future release.
* [`POST /register`](/api/register-queue): The response now supports a
  `realm_linkifiers` event type, containing the same data as the
  legacy `realm_filters` key, with a more extensible object
  format. The previous `realm_filters` event type is still supported
  for backwards compatibility, but will be removed in a future
  release. The legacy `realm_filters` key is deprecated but remains
  available for backwards compatibility.

**Feature level 53**

* [`POST /register`](/api/register-queue): Added `max_topic_length`
  and `max_message_length`, and renamed `max_stream_name_length` and
  `max_stream_description_length` to allow clients to transparently
  support these values changing in a future server version.

**Feature level 52**

* `PATCH /realm`: Removed unnecessary JSON-encoding of string
  parameters `name`, `description`, `default_language`, and
  `default_code_block_language`.

**Feature level 51**

* [`POST /register`](/api/register-queue): Added a new boolean field
`can_invite_others_to_realm`.

**Feature level 50**

* [`POST /register`](/api/register-queue): Replaced `invite_by_admins_only`
field with an integer field `invite_to_realm_policy`.

**Feature level 49**

* Added new [`POST /realm/playground`](/api/add-code-playground) and
  [`DELETE /realm/playground/{playground_id}`](/api/remove-code-playground)
  endpoints for code playgrounds.
* [`GET /events`](/api/get-events): A new `realm_playgrounds` events
  is sent when changes are made to a set of configured code playgrounds for
  an organization.
* [`POST /register`](/api/register-queue): Added a new `realm_playgrounds`
  field, which is required to fetch the set of configured code playgrounds for
  an organization.

**Feature level 48**

* [`POST /users/me/muted_users/{muted_user_id}`](/api/mute-user),
  [`DELETE /users/me/muted_users/{muted_user_id}`](/api/unmute-user):
  New endpoints added to mute/unmute users.
* [`GET /events`](/api/get-events): Added new event type `muted_users`
  which will be sent to a user when the set of users muted by them has
  changed.

**Feature level 47**

* [`POST /register`](/api/register-queue): Added a new `giphy_api_key`
  field, which is required to fetch GIFs using the GIPHY API.

**Feature level 46**

* [`GET /messages`](/api/get-messages) and [`GET
  /events`](/api/get-events): The `topic_links` field now contains a
  list of dictionaries, rather than a list of strings.

**Feature level 45**

* [`GET /events`](/api/get-events): Removed useless `op` field from
  `custom_profile_fields` events.  These events contain the full set
  of configured `custom_profile_fields` for the organization
  regardless of what triggered the change.

**Feature level 44**

* [`POST /register`](/api/register-queue): extended the `unread_msgs`
  object to include `old_unreads_missing`, which indicates whether the
  server truncated the `unread_msgs` due to excessive total unread
  messages.

**Feature level 43**

* [`GET /users/{user_id_or_email}/presence`](/api/get-user-presence):
  Added support for passing the `user_id` to identify the target user.

**Feature level 42**

* `PATCH /settings/display`: Added a new `default_view` setting allowing
  the user to [set the default view](/help/configure-default-view).

**Feature level 41**

* [`GET /events`](/api/get-events): Removed `name` field from update
  subscription events.

**Feature level 40**

* [`GET /events`](/api/get-events): Removed `email` field from update
  subscription events.

**Feature level 39**

* Added new [`GET /users/{email}`](/api/get-user-by-email) endpoint.

**Feature level 38**

* [`POST /register`](/api/register-queue): Increased
  `realm_community_topic_editing_limit_seconds` time limit value
  to 259200s (3 days).

**Feature level 37**

* Consistently provide `subscribers` in stream data when
  clients register for subscriptions with `include_subscribers`,
  even if the user can't access subscribers.

**Feature level 36**

* [`POST /users`](/api/create-user): Restricted access to organization
  administrators with the `can_create_users` permission.
* [Error handling](/api/rest-error-handling): The `code` property will
  now be present in errors due to rate limits.

**Feature level 35**

* The peer_add and peer_remove subscription events now have plural
  versions of `user_ids` and `stream_ids`.

**Feature level 34**

* [`POST /register`](/api/register-queue): Added a new `wildcard_mention_policy`
  setting for controlling who can use wildcard mentions in large streams.

**Feature level 33**

* Markdown code blocks now have a `data-code-language` attribute
  attached to the outer `div` element, recording the programming
  language that was selecting for syntax highlighting.  This field
  supports the upcoming "view in playground" feature for code blocks.

**Feature level 32**

* [`GET /events`](/api/get-events): Added `op` field to
  `update_message_flags` events, deprecating the `operation` field
  (which has the same value).  This removes an unintentional anomaly
  in the format of this event type.

**Feature level 31**

* [`GET users/me/subscriptions`](/api/get-subscriptions): Added a
  `role` field to Subscription objects representing whether the user
  is a stream administrator.

* [`GET /events`](/api/get-events): Added `role` field to
  Subscription objects sent in `subscriptions` events.

Note that as of this feature level, stream administrators are a
partially completed feature.  In particular, it is impossible for a
user to be a stream administrator at this feature level.

**Feature level 30**

* [`GET users/me/subscriptions`](/api/get-subscriptions), [`GET
  /streams`](/api/get-streams): Added `date_created` to Stream
  objects.
* [`POST /users`](/api/create-user), `POST /bots`: The ID of the newly
  created user is now returned in the response.

Feature levels 28 and 29 are reserved for future use in 3.x bug fix
releases.

## Changes in Zulip 3.1

**Feature level 27**

* [`POST /users`](/api/create-user): Removed `short_name` field from
  `display_recipient` array objects.

**Feature level 26**

* [`GET /messages`](/api/get-messages): `sender_short_name` field is no
  longer included in return values for this endpoint.
* [`GET /messages`](/api/get-messages) : Removed `short_name` field from
  `display_recipient` array objects.

## Changes in Zulip 3.0

**Feature level 25**

No changes; feature level used for Zulip 3.0 release.

**Feature level 24**

* The `!avatar()` and `!gravatar()` Markdown syntax, which was never
  documented, had inconsistent syntax, and was rarely used, was
  removed.

**Feature level 23**

* `GET/PUT/POST /users/me/pointer`: Removed.  Zulip 3.0 removes the
  `pointer` concept from Zulip; this legacy data structure was
  replaced by tracking unread messages and loading views centered on
  the first unread message.

**Feature level 22**

* [`GET /attachments`](/api/get-attachments): The date when a message
  using the attachment was sent is now correctly encoded as
  `date_sent`, replacing the confusingly named `name` field.  The
  `date_sent` and `create_time` fields of attachment objects are now
  encoded as integers; (previously the implementation could send
  floats incorrectly suggesting that microsecond precision is
  relevant).
* `GET /invites`: Now encodes the user ID of the person who created
   the invitation as `invited_by_user_id`, replacing the previous
   `ref` field (which had that user's Zulip display email address).
* [`POST /register`](/api/register-queue): The encoding of an
  unlimited `realm_message_retention_days` in the response was changed
  from `null` to `-1`.

**Feature level 21**

* `PATCH /settings/display`: Replaced the `night_mode` boolean with
  `color_scheme` as part of supporting automatic night theme detection.

**Feature level 20**

* Added support for inviting users as organization owners to the
  invitation endpoints.

**Feature level 19**

* [`GET /events`](/api/get-events): `subscriptions` event with
  `op="peer_add"` and `op="peer_remove"` now identify the modified
  stream by a `stream_id` field, replacing the old `name` field.

**Feature level 18**

* [`POST /register`](/api/register-queue): Added
  `user_avatar_url_field_optional` to supported `client_capabilities`.

**Feature level 17**

* [`GET users/me/subscriptions`](/api/get-subscriptions),
  [`GET /streams`](/api/get-streams): Added
  `message_retention_days` to Stream objects.
* [`POST users/me/subscriptions`](/api/subscribe), [`PATCH
  streams/{stream_id}`](/api/update-stream): Added `message_retention_days`
  parameter.

**Feature level 16**

* [`GET /users/me`](/api/get-own-user): Removed `pointer` from the response,
  as the "pointer" concept is being removed in Zulip.
* Changed the rendered HTML markup for mentioning a time to use the
  `<time>` HTML tag.  It is OK for clients to ignore the previous time
  mention markup, as the feature was not advertised before this change.

**Feature level 15**

* Added [spoilers](/help/format-your-message-using-markdown#spoilers)
  to supported Markdown features.

**Feature level 14**

* [`GET users/me/subscriptions`](/api/get-subscriptions): Removed
  the `is_old_stream` field from Stream objects.  This field was
  always equivalent to `stream_weekly_traffic != null` on the same object.

**Feature level 13**

* [`POST /register`](/api/register-queue): Added
  `bulk_message_deletion` to supported `client_capabilities`.
* [`GET /events`](/api/get-events): `delete_message`
  events have new behavior.  The `sender` and `sender_id` fields were
  removed, and the `message_id` field was replaced by a `message_ids`
  list for clients with the `bulk_message_deletion` client capability.
  All clients should upgrade; we expect `bulk_message_deletion` to be
  required in the future.

**Feature level 12**

* [`GET users/{user_id}/subscriptions/{stream_id}`](/api/get-subscription-status):
  New endpoint added for checking if another user is subscribed to a stream.

**Feature level 11**

* [`POST /register`](/api/register-queue): Added
  `realm_community_topic_editing_limit_seconds` to the response, the
  time limit before community topic editing is forbidden.  A `null`
  value means no limit. This was previously hard-coded in the server
  as 86400 seconds (1 day).
* [`POST /register`](/api/register-queue): The response now contains a
  `is_owner`, similar to the existing `is_admin` and `is_guest` fields.
* [`POST /set-typing-status`](/api/set-typing-status): Removed legacy support for sending email
  addresses, rather than user IDs, to encode private message recipients.

**Feature level 10**

* [`GET users/me`](/api/get-own-user): Added `avatar_version`, `is_guest`,
  `is_active`, `timezone`, and `date_joined` fields to the User objects.
* [`GET users/me`](/api/get-own-user): Removed `client_id` and `short_name`
  from the response to this endpoint.  These fields had no purpose and
  were inconsistent with other API responses describing users.

**Feature level 9**

* [`POST users/me/subscriptions`](/api/subscribe), [`DELETE
  /users/me/subscriptions`](/api/unsubscribe): Other users to
  subscribe/unsubscribe, declared in the `principals` parameter, can
  now be referenced by user_id, rather than Zulip display email
  address.
* [`PATCH /messages/{message_id}`](/api/update-message): Added
  `send_notification_to_old_thread` and
  `send_notification_to_new_thread` optional parameters.

**Feature level 8**

* [`GET /users`](/api/get-users), [`GET /users/{user_id}`](/api/get-user)
  and [`GET /users/me`](/api/get-own-user): User objects now contain the
  `is_owner` field as well.
* Added [time mentions](/help/format-your-message-using-markdown#mention-a-time)
  to supported Markdown features.

**Feature level 7**

* [`GET /events`](/api/get-events): `realm_user` and
  `realm_bot` events no longer contain an `email` field to identify
  the user; use the `user_id` field instead.  Previously, some (but
  not all) events of these types contained an `email` key in addition to
  to `user_id`) for identifying the modified user.
* [`PATCH /users/{user_id}`](/api/update-user): The `is_admin` and
  `is_guest` parameters were removed in favor of the more general
  `role` parameter for specifying a change in user role.
* [`GET /events`](/api/get-events): `realm_user` events
  sent when a user's role changes now include `role` property, instead
  of the previous `is_guest` or `is_admin` booleans.
* [`GET /realm/emoji`](/api/get-custom-emoji): The user who uploaded a
  given custom emoji is now indicated by an `author_id` field, replacing
  a previous `author` object that had unnecessary additional data.

**Feature level 6**

* [`GET /events`](/api/get-events): `realm_user` events to
  update a user's avatar now include the `avatar_version` field, which
  is important for correctly refetching medium-size avatar images when
  the user's avatar changes.
* [`GET /users`](/api/get-users) and [`GET
  /users/{user_id}`](/api/get-user): User objects now contain the
  `avatar_version` field as well.

**Feature level 5**

* [`GET /events`](/api/get-events): `realm_bot` events,
  sent when changes are made to bot users, now contain an
  integer-format `owner_id` field, replacing the `owner` field (which
  was an email address).

**Feature level 4**

* `jitsi_server_url`, `development_environment`, `server_generation`,
  `password_min_length`, `password_min_guesses`, `max_file_upload_size_mib`,
  `max_avatar_file_size_mib`, `server_inline_image_preview`,
  `server_inline_url_embed_preview`, `server_avatar_changes_disabled` and
  `server_name_changes_disabled` fields are now available via
  `POST /register` to make them accessible to all the clients;
  they were only internally available to Zulip's web app prior to this.

**Feature level 3**

* [`POST /register`](/api/register-queue): `zulip_version` and
  `zulip_feature_level` are always returned in the endpoint response.
  Previously, they were only present if `event_types` included
  `zulip_version`.
* Added new `presence_enabled` user notification setting; previously
  [presence](/help/status-and-availability) was always enabled.

**Feature level 2**:

* [`POST /messages/{message_id}/reactions`](/api/add-reaction):
  The `reaction_type` parameter is optional; the server will guess the
  `reaction_type` if it is not specified (checking custom emoji, then
  Unicode emoji for any with the provided name).
* `reactions` objects returned by the API (both in `GET /messages` and
  in `GET /events`) now include the user who reacted in a top-level
  `user_id` field.  The legacy `user` dictionary (which had
  inconsistent format between those two endpoints) is deprecated.

**Feature level 1**:

* [`PATCH /messages/{message_id}`](/api/update-message): Added the
  `stream_id` parameter to support moving messages between streams.
* [`GET /messages`](/api/get-messages), [`GET /events`](/api/get-events):
  Added `prev_stream` as a potential property of the `edit_history` object
  within message objects to indicate when a message was moved to another
  stream.
* [`GET messages/{message_id}/history`](/api/get-message-history):
  `prev_stream` is present in `snapshot` objects within `message_history`
  object when a message was moved to another stream.
* [`GET /server_settings`](/api/get-server-settings): Added
  `zulip_feature_level`, which can be used by clients to detect which
  of the features described in this changelog are supported.
* [`POST /register`](/api/register-queue): Added `zulip_feature_level`
  to the response if `zulip_version` is among the requested
  `event_types`.
* [`GET /users`](/api/get-users): User objects for bots now
  contain a `bot_owner_id`, replacing the previous `bot_owner` field
  (which had the email address of the bot owner).
* [`GET /users/{user_id}`](/api/get-user): New endpoint added to get
  a single user's details by the user's ID.
* [`GET /messages`](/api/get-messages): Add support for string-format
  values for the `anchor` parameter, deprecating and replacing the
  `use_first_unread_anchor` parameter.
* [`GET /messages`](/api/get-messages), [`GET /events`](/api/get-events):
  Message objects now use `topic_links` rather than `subject_links` to
  indicate links either present in the topic or generated by linkifiers
  applied to the topic.
* [`GET /streams`](/api/get-streams),
  [`POST /users/me/subscriptions`](/api/subscribe),
  [`PATCH /streams/{stream_id}`](/api/update-stream): Stream objects now
  have `stream_post_policy` enum for specifying who can post to the stream,
  deprecating and replacing the `is_announcement_only` boolean.
* [`GET /user_uploads/{realm_id_str}/{filename}`](/api/get-file-temporary-url):
  New endpoint added for requesting a temporary URL for an uploaded
  file that does not require authentication to access (e.g. for passing
  from a Zulip desktop, mobile, or terminal app to the user's default
  browser).
* [`POST /register`](/api/register-queue), [`GET /events`](/api/get-events),
  `PATCH /realm`: Nobody added as an option for the realm setting
  `email_address_visibility`.
* [`POST /register`](/api/register-queue), [`GET /events`](/api/get-events),
  `PATCH /realm`: Added realm setting `private_message_policy`.
* [`POST /register`](/api/register-queue), [`GET /events`](/api/get-events):
  `muted_topics` array objects now are 3-item tuples that include the
  stream name, the topic name, and the time when the topic was muted.
  Previously, they were 2-item tuples and did not include the time when
  the topic was muted.
* [`GET /server_settings`](/api/get-server-settings): Added `gitlab` boolean
  to deprecated `authentication_methods` object.
* [`POST /register`](/api/register-queue), [`GET /events`](/api/get-events),
  `PATCH /realm`: None added as an option for the realm setting
  `video_chat_provider` to disable video call UI.

## Changes in Zulip 2.1

* [`POST /register`](/api/register-queue): Added
  `realm_default_external_accounts` to endpoint response.
* [`GET /messages`](/api/get-messages): Added support for
  [search/narrow options](/api/construct-narrow) that use stream/user
  IDs to specify a message's sender, its stream, and/or its recipient(s).
* [`GET /users`](/api/get-users): Added `include_custom_profile_fields`
  to request custom profile field data.
* [`GET /users/me`](/api/get-own-user): Added `avatar_url` field,
  containing the user's avatar URL, to the response.
* [`GET /users/me/subscriptions`](/api/get-subscriptions): Added
  `include_subscribers` parameter controlling whether data on the
  other subscribers is included.  Previous behavior was to always send
  subscriber data.
* [`GET /users/me/subscriptions`](/api/get-subscriptions):
  Stream-level notification settings like `push_notifications` were
  changed to be nullable boolean fields (true/false/null), with `null`
  meaning that the stream inherits the organization-level default.
  Previously, the only values were true/false.  A client communicates
  support for this feature using `client_capabilities`.
* [`GET /users/me/subscriptions`](/api/get-subscriptions): Added
  `wildcard_mentions_notify` notification setting, with the same
  global-plus-stream-level-override model as other notification settings.
* [`GET /server_settings`](/api/get-server-settings): Added
  `external_authentication_methods` structure, used to display login
  buttons nicely in the mobile apps.
* Added `first_message_id` field to Stream objects.  This is helpful
  for determining whether the stream has any messages older than a
  window cached in a client.
* Added `is_web_public` field to Stream objects.  This field is
  intended to support web-public streams.
* Added `/export/realm` endpoints for triggering a data export.
* `PATCH /realm`: Added `invite_to_stream_policy`,
  `create_stream_policy`, `digest_emails_enabled`, `digest_weekday`,
  `user_group_edit_policy`, and `avatar_changes_disabled` organization settings.
* Added `fluid_layout_width`, `desktop_icon_count_display`, and
  `demote_inactive_streams` display settings.
* `enable_stream_sounds` was renamed to
  `enable_stream_audible_notifications`.
* [`POST /users/me/subscriptions/properties`](/api/update-subscription-settings):
  Deprecated `in_home_view`, replacing it with the more readable
  `is_muted` (with the opposite meaning).
* Custom profile fields: Added `EXTERNAL_ACCOUNT` field type.

## Changes in Zulip 2.0

* [`PATCH /users/me/subscriptions/muted_topics`](/api/mute-topic):
  Added support for using stream IDs to specify the stream in which to
  mute/unmute a topic.
* [`POST /messages`](/api/send-message): Added support for using user
  IDs and stream IDs for specifying the recipients of a message.
* [`POST /messages`](/api/send-message), [`POST
  /messages/{message_id}`](/api/update-message): Added support for
  encoding topics using the `topic` parameter name.  The previous
  `subject` parameter name was deprecated but is still supported for
  backwards-compatibility.
* [`POST /set-typing-status`](/api/set-typing-status): Added support for specifying the
  recipients with user IDs, deprecating the original API of specifying
  them using email addresses.

------------------

## Changes not yet stabilized

* [`POST /register`](/api/register-queue): Added `slim_presence`
  parameter.  Changes the format of presence events, but is still
  being changed and should not be used by clients.

[server-changelog]: https://zulip.readthedocs.io/en/latest/overview/changelog.html
[release-lifecycle]: https://zulip.readthedocs.io/en/latest/overview/release-lifecycle.html
[rfc6570]: https://www.rfc-editor.org/rfc/rfc6570.html