Zulip supports integration with CircleCI and can notify you of your build statuses.

First, create the stream you'd like to use for CircleCI notifications, and subscribe all interested parties to this stream. We recommend the name circleci.

{{ external_api_uri_subdomain }}/v1/external/circleci?api_key=abcdefgh&stream=circleci

where api_key is the API key of your Zulip bot, and stream is the stream name you want the notifications sent to.

Next, modify your circle.yml as described here.

Congratulations! You're done!
When a build is done, you'll get a notification like this: