diff --git a/puppet/zulip/files/nagios_plugins/zulip_app_frontend/check_cron_file b/puppet/zulip/files/nagios_plugins/zulip_app_frontend/check_cron_file
index 6aca1d95e0..123fe8f257 100755
--- a/puppet/zulip/files/nagios_plugins/zulip_app_frontend/check_cron_file
+++ b/puppet/zulip/files/nagios_plugins/zulip_app_frontend/check_cron_file
@@ -18,7 +18,8 @@ def nagios_from_file(results_file: str, max_time_diff: int=60 * 2) -> 'Tuple[int
     This file is created by various nagios checking cron jobs such as
     check-rabbitmq-queues and check-rabbitmq-consumers"""
 
-    data = open(results_file).read().strip()
+    with open(results_file, 'r') as f:
+        data = f.read().strip()
     pieces = data.split('|')
 
     if not len(pieces) == 4:
diff --git a/puppet/zulip_ops/files/nagios_plugins/zulip_zephyr_mirror/check_personal_zephyr_mirrors b/puppet/zulip_ops/files/nagios_plugins/zulip_zephyr_mirror/check_personal_zephyr_mirrors
index 1e339eb5d9..c8e78d84d3 100755
--- a/puppet/zulip_ops/files/nagios_plugins/zulip_zephyr_mirror/check_personal_zephyr_mirrors
+++ b/puppet/zulip_ops/files/nagios_plugins/zulip_zephyr_mirror/check_personal_zephyr_mirrors
@@ -34,7 +34,8 @@ down_count = 0
 for results_file_name in os.listdir(RESULTS_DIR):
     this_state = "OK"
     results_file = os.path.join(RESULTS_DIR, results_file_name)
-    data = open(results_file).read().strip()
+    with open(results_file, 'r') as f:
+        data = f.read().strip()
     last_check = os.stat(results_file).st_mtime
     time_since_last_check = time.time() - last_check
     # time_since_last_check threshold needs to be strictly greater
diff --git a/puppet/zulip_ops/files/nagios_plugins/zulip_zephyr_mirror/check_zephyr_mirror b/puppet/zulip_ops/files/nagios_plugins/zulip_zephyr_mirror/check_zephyr_mirror
index 66b70ccdd4..69569d9360 100755
--- a/puppet/zulip_ops/files/nagios_plugins/zulip_zephyr_mirror/check_zephyr_mirror
+++ b/puppet/zulip_ops/files/nagios_plugins/zulip_zephyr_mirror/check_zephyr_mirror
@@ -32,7 +32,8 @@ def report(state, data, last_check):
         data))
     exit(states[state])
 
-data = open(RESULTS_FILE).read().strip()
+with open(RESULTS_FILE, 'r') as f:
+    data = f.read().strip()
 if data.split("\n")[-1].strip() == "0":
     state = "OK"
 else:
diff --git a/scripts/lib/setup_venv.py b/scripts/lib/setup_venv.py
index 533ad2dda5..92c8c2d55e 100644
--- a/scripts/lib/setup_venv.py
+++ b/scripts/lib/setup_venv.py
@@ -260,16 +260,14 @@ def do_patch_activate_script(venv_path):
     # venv_path should be what we want to have in VIRTUAL_ENV after patching
     script_path = os.path.join(venv_path, "bin", "activate")
 
-    file_obj = open(script_path)
-    lines = file_obj.readlines()
+    with open(script_path, 'r') as f:
+        lines = f.readlines()
     for i, line in enumerate(lines):
         if line.startswith('VIRTUAL_ENV='):
             lines[i] = 'VIRTUAL_ENV="%s"\n' % (venv_path,)
-    file_obj.close()
 
-    file_obj = open(script_path, 'w')
-    file_obj.write("".join(lines))
-    file_obj.close()
+    with open(script_path, 'w') as f:
+        f.write("".join(lines))
 
 def setup_virtualenv(target_venv_path, requirements_file, virtualenv_args=None, patch_activate_script=False):
     # type: (Optional[str], str, Optional[List[str]], bool) -> str
@@ -285,7 +283,8 @@ def setup_virtualenv(target_venv_path, requirements_file, virtualenv_args=None,
     success_stamp = os.path.join(cached_venv_path, "success-stamp")
     if not os.path.exists(success_stamp):
         do_setup_virtualenv(cached_venv_path, requirements_file, virtualenv_args or [])
-        open(success_stamp, 'w').close()
+        with open(success_stamp, 'w') as f:
+            f.close()
 
     print("Using cached Python venv from %s" % (cached_venv_path,))
     if target_venv_path is not None:
diff --git a/scripts/nagios/cron_file_helper.py b/scripts/nagios/cron_file_helper.py
index abdf90dcc5..268274050a 100644
--- a/scripts/nagios/cron_file_helper.py
+++ b/scripts/nagios/cron_file_helper.py
@@ -14,7 +14,8 @@ def nagios_from_file(results_file):
     This file is created by various nagios checking cron jobs such as
     check-rabbitmq-queues and check-rabbitmq-consumers"""
 
-    data = open(results_file).read().strip()
+    with open(results_file) as f:
+        data = f.read().strip()
     pieces = data.split('|')
 
     if not len(pieces) == 4:
diff --git a/scripts/setup/generate_secrets.py b/scripts/setup/generate_secrets.py
index 0596ddd549..5f8c2aa0ae 100755
--- a/scripts/setup/generate_secrets.py
+++ b/scripts/setup/generate_secrets.py
@@ -108,11 +108,10 @@ def generate_secrets(development=False):
         print("generate_secrets: No new secrets to generate.")
         return
 
-    out = open(OUTPUT_SETTINGS_FILENAME, 'a')
-    # Write a newline at the start, in case there was no newline at
-    # the end of the file due to human editing.
-    out.write("\n" + "".join(lines))
-    out.close()
+    with open(OUTPUT_SETTINGS_FILENAME, 'a') as f:
+        # Write a newline at the start, in case there was no newline at
+        # the end of the file due to human editing.
+        f.write("\n" + "".join(lines))
 
     print("Generated new secrets in %s." % (OUTPUT_SETTINGS_FILENAME,))
 
diff --git a/tools/get-handlebar-vars b/tools/get-handlebar-vars
index f4a049dc19..75a64093ea 100755
--- a/tools/get-handlebar-vars
+++ b/tools/get-handlebar-vars
@@ -15,7 +15,8 @@ def debug(obj):
 
 def parse_file(fn):
     # type: (str) -> Dict[str, Any]
-    text = open(fn).read()
+    with open(fn, 'r') as f:
+        text = f.read()
     tags = re.findall(r'{+\s*(.*?)\s*}+', text)
     root = {}  # type: Dict[str, Any]
     context = root
diff --git a/tools/lib/html_branches.py b/tools/lib/html_branches.py
index 23b8e1431f..702914dd04 100644
--- a/tools/lib/html_branches.py
+++ b/tools/lib/html_branches.py
@@ -193,7 +193,8 @@ def build_id_dict(templates):
     template_id_dict = defaultdict(list)  # type: (Dict[str, List[str]])
 
     for fn in templates:
-        text = open(fn).read()
+        with open(fn, 'r') as f:
+            text = f.read()
         list_tags = tokenize(text)
 
         for tag in list_tags:
diff --git a/tools/lib/html_grep.py b/tools/lib/html_grep.py
index 4f68ad82cf..7a9387ed15 100644
--- a/tools/lib/html_grep.py
+++ b/tools/lib/html_grep.py
@@ -7,7 +7,8 @@ def show_all_branches(fns):
     # type: (List[str]) -> None
     for fn in fns:
         print(fn)
-        text = open(fn).read()
+        with open(fn, 'r') as f:
+            text = f.read()
         branches = html_branches(text, fn=fn)
         for branch in branches:
             print(branch.text())
@@ -25,7 +26,8 @@ class Grepper:
         all_branches = []  # type: List[HtmlTreeBranch]
 
         for fn in fns:
-            text = open(fn).read()
+            with open(fn, 'r') as f:
+                text = f.read()
             branches = html_branches(text, fn=fn)
             all_branches += branches
 
diff --git a/tools/lib/pretty_print.py b/tools/lib/pretty_print.py
index 3c257941e8..a44ae6a7b1 100644
--- a/tools/lib/pretty_print.py
+++ b/tools/lib/pretty_print.py
@@ -194,10 +194,9 @@ def pretty_print_html(html, num_spaces=4):
 
 def validate_indent_html(fn, fix):
     # type: (str, bool) -> int
-    file = open(fn)
-    html = file.read()
+    with open(fn, 'r') as f:
+        html = f.read()
     phtml = pretty_print_html(html)
-    file.close()
     if not html.split('\n') == phtml.split('\n'):
         if fix:
             print(GREEN + "Automatically fixing problems..." + ENDC)
diff --git a/tools/lib/template_parser.py b/tools/lib/template_parser.py
index b49f53e78a..24510dc2f9 100644
--- a/tools/lib/template_parser.py
+++ b/tools/lib/template_parser.py
@@ -214,7 +214,8 @@ def validate(fn=None, text=None, check_indent=True):
         fn = '<in memory file>'
 
     if text is None:
-        text = open(fn).read()
+        with open(fn, 'r') as f:
+            text = f.read()
 
     tokens = tokenize(text)
 
diff --git a/tools/lib/test_script.py b/tools/lib/test_script.py
index 51139de3ac..4d4b1b6ca0 100644
--- a/tools/lib/test_script.py
+++ b/tools/lib/test_script.py
@@ -56,7 +56,8 @@ def get_provisioning_status():
         # their own dependencies and not running provision.
         return True, None
 
-    version = open(version_file).read().strip()
+    with open(version_file, 'r') as f:
+        version = f.read().strip()
 
     # Normal path for people that provision--we're all good!
     if version == PROVISION_VERSION:
diff --git a/tools/pretty-print-html b/tools/pretty-print-html
index 6352d35c4f..2d104e701e 100755
--- a/tools/pretty-print-html
+++ b/tools/pretty-print-html
@@ -7,13 +7,11 @@ def clean_html(filenames):
     # type: (List[str]) -> None
     for fn in filenames:
         print('Prettifying: %s' % (fn,))
-        file = open(fn)
-        html = file.read()
+        with open(fn, 'r') as f:
+            html = f.read()
         phtml = pretty_print_html(html)
-        file.close()
-        file = open(fn, 'w')
-        file.write(phtml)
-        file.close()
+        with open(fn, 'w') as f:
+            f.write(phtml)
 
 if __name__ == '__main__':
     # If command arguments are provided, we only check those filenames.
diff --git a/tools/run-dev.py b/tools/run-dev.py
index d8861a76eb..4b3e978bd3 100755
--- a/tools/run-dev.py
+++ b/tools/run-dev.py
@@ -133,9 +133,8 @@ else:
 # Required for compatibility python versions.
 if not os.path.exists(os.path.dirname(pid_file_path)):
     os.makedirs(os.path.dirname(pid_file_path))
-pid_file = open(pid_file_path, 'w+')
-pid_file.write(str(os.getpgrp()) + "\n")
-pid_file.close()
+with open(pid_file_path, 'w+') as f:
+    f.write(str(os.getpgrp()) + "\n")
 
 # Pass --nostatic because we configure static serving ourselves in
 # zulip/urls.py.
diff --git a/tools/setup/emoji/build_emoji b/tools/setup/emoji/build_emoji
index e7308b1d7d..3cc4e5f996 100755
--- a/tools/setup/emoji/build_emoji
+++ b/tools/setup/emoji/build_emoji
@@ -92,7 +92,8 @@ def main() -> None:
     if not os.path.exists(success_stamp):
         print("Dumping emojis ...")
         dump_emojis(source_emoji_dump)
-        open(success_stamp, 'w').close()
+        with open(success_stamp, 'w') as f:
+            f.close()
 
     print("Using cached emojis from {}".format(source_emoji_dump))
     if os.path.lexists(TARGET_EMOJI_DUMP):
@@ -135,11 +136,10 @@ def generate_sprite_css_files(cache_path: str,
             }
 
     SPRITE_CSS_PATH = os.path.join(cache_path, '%s-sprite.css' % (emojiset,))
-    sprite_css_file = open(SPRITE_CSS_PATH, 'w')
-    sprite_css_file.write(SPRITE_CSS_FILE_TEMPLATE % {'emojiset': emojiset,
-                                                      'emoji_positions': emoji_positions,
-                                                      })
-    sprite_css_file.close()
+    with open(SPRITE_CSS_PATH, 'w') as f:
+        f.write(SPRITE_CSS_FILE_TEMPLATE % {'emojiset': emojiset,
+                                            'emoji_positions': emoji_positions,
+                                            })
 
 def setup_emoji_farms(cache_path: str, emoji_data: List[Dict[str, Any]]) -> None:
     def ensure_emoji_image(emoji_dict: Dict[str, Any],
diff --git a/tools/setup/emoji/export_emoji_names_to_csv b/tools/setup/emoji/export_emoji_names_to_csv
index b3cfe9d668..db90880e2d 100755
--- a/tools/setup/emoji/export_emoji_names_to_csv
+++ b/tools/setup/emoji/export_emoji_names_to_csv
@@ -115,8 +115,8 @@ def main() -> None:
                 explanation_line = match.group('explanation_line').strip()
                 explanation_lines.append(explanation_line)
 
-    fp = open(args.output_file_path, 'w')
-    writer = csv.writer(fp, dialect='excel')
+    with open(args.output_file_path, 'w') as f:
+        writer = csv.writer(f, dialect='excel')
     writer.writerows(output_data)
     # The CSV file exported by google sheets doesn't have a newline
     # character in the end. So we also strip the last newline character
diff --git a/tools/zulip-export/zulip-export b/tools/zulip-export/zulip-export
index e531354f2d..feb79524b3 100755
--- a/tools/zulip-export/zulip-export
+++ b/tools/zulip-export/zulip-export
@@ -83,8 +83,7 @@ for msg in result['messages']:
     messages.append(msg)
 
 filename = "zulip-%s.json" % (options.stream,)
-f = open(filename, mode="wb")
-f.write(json.dumps(messages, indent=0, sort_keys=False).encode('utf-8'))
-f.close()
+with open(filename, 'wb') as f:
+    f.write(json.dumps(messages, indent=0, sort_keys=False).encode('utf-8'))
 print("%d messages exported to %s" % (len(messages), filename,))
 sys.exit(0)
diff --git a/zerver/lib/api_test_helpers.py b/zerver/lib/api_test_helpers.py
index 23d7986ae9..635859bc7b 100644
--- a/zerver/lib/api_test_helpers.py
+++ b/zerver/lib/api_test_helpers.py
@@ -800,12 +800,12 @@ def upload_file(client):
 
     # {code_example|start}
     # Upload a file
-    fp = open(path_to_file, 'rb')
-    result = client.call_endpoint(
-        'user_uploads',
-        method='POST',
-        files=[fp]
-    )
+    with open(path_to_file, 'rb') as fp:
+        result = client.call_endpoint(
+            'user_uploads',
+            method='POST',
+            files=[fp]
+        )
     # {code_example|end}
 
     validate_against_openapi_schema(result, '/user_uploads', 'post', '200')
@@ -851,15 +851,15 @@ def upload_custom_emoji(client):
 
     # {code_example|start}
     # Upload a custom emoji; assume `emoji_path` is the path to your image.
-    fp = open(emoji_path, 'rb')
-    emoji_name = 'my_custom_emoji'
-    result = client.call_endpoint(
-        'realm/emoji/{}'.format(emoji_name),
-        method='POST',
-        files=[fp]
-    )
+    with open(emoji_path, 'rb') as fp:
+        emoji_name = 'my_custom_emoji'
+        result = client.call_endpoint(
+            'realm/emoji/{}'.format(emoji_name),
+            method='POST',
+            files=[fp]
+        )
     # {code_example|end}
-    fp.close()
+
     validate_against_openapi_schema(result,
                                     '/realm/emoji/{emoji_name}',
                                     'post', '200')
diff --git a/zerver/lib/debug.py b/zerver/lib/debug.py
index 165a158726..fc112ccffe 100644
--- a/zerver/lib/debug.py
+++ b/zerver/lib/debug.py
@@ -53,7 +53,8 @@ def tracemalloc_dump() -> None:
     gc.collect()
     tracemalloc.take_snapshot().dump(path)
 
-    procstat = open('/proc/{}/stat'.format(os.getpid()), 'rb').read().split()
+    with open('/proc/{}/stat'.format(os.getpid()), 'rb') as f:
+        procstat = f.read().split()
     rss_pages = int(procstat[23])
     logger.info("tracemalloc dump: tracing {} MiB ({} MiB peak), using {} MiB; rss {} MiB; dumped {}"
                 .format(tracemalloc.get_traced_memory()[0] // 1048576,
diff --git a/zerver/lib/export.py b/zerver/lib/export.py
index df6556c7ff..5856eccb54 100644
--- a/zerver/lib/export.py
+++ b/zerver/lib/export.py
@@ -1375,7 +1375,8 @@ def do_write_stats_file_for_realm_export(output_dir: Path) -> None:
     with open(stats_file, 'w') as f:
         for fn in fns:
             f.write(os.path.basename(fn) + '\n')
-            payload = open(fn).read()
+            with open(fn, 'r') as filename:
+                payload = filename.read()
             data = ujson.loads(payload)
             for k in sorted(data):
                 f.write('%5d %s\n' % (len(data[k]), k))
@@ -1386,7 +1387,8 @@ def do_write_stats_file_for_realm_export(output_dir: Path) -> None:
 
         for fn in [avatar_file, uploads_file]:
             f.write(fn+'\n')
-            payload = open(fn).read()
+            with open(fn, 'r') as filename:
+                payload = filename.read()
             data = ujson.loads(payload)
             f.write('%5d records\n' % (len(data),))
             f.write('\n')
diff --git a/zerver/lib/upload.py b/zerver/lib/upload.py
index 9bab2bd94d..d08c4b1562 100644
--- a/zerver/lib/upload.py
+++ b/zerver/lib/upload.py
@@ -735,7 +735,8 @@ class LocalUploadBackend(ZulipUploadBackend):
             return
 
         image_path = os.path.join(settings.LOCAL_UPLOADS_DIR, "avatars", file_path + ".original")
-        image_data = open(image_path, "rb").read()
+        with open(image_path, "rb") as f:
+            image_data = f.read()
         resized_medium = resize_avatar(image_data, MEDIUM_AVATAR_SIZE)
         write_local_file('avatars', file_path + '-medium.png', resized_medium)
 
@@ -748,7 +749,8 @@ class LocalUploadBackend(ZulipUploadBackend):
             return
 
         image_path = os.path.join(settings.LOCAL_UPLOADS_DIR, "avatars", file_path + ".original")
-        image_data = open(image_path, "rb").read()
+        with open(image_path, "rb") as f:
+            image_data = f.read()
         resized_avatar = resize_avatar(image_data)
         write_local_file('avatars', file_path + '.png', resized_avatar)
 
diff --git a/zerver/logging_handlers.py b/zerver/logging_handlers.py
index a2b8290c14..1bf6b78740 100644
--- a/zerver/logging_handlers.py
+++ b/zerver/logging_handlers.py
@@ -31,7 +31,8 @@ def add_deployment_metadata(report: Dict[str, Any]) -> None:
 
     version_path = os.path.join(os.path.dirname(__file__), '../version')
     if os.path.exists(version_path):
-        report['zulip_version_file'] = open(version_path).read().strip()  # nocoverage
+        with open(version_path, 'r') as f:  # nocoverage
+            report['zulip_version_file'] = f.read().strip()
 
 def add_request_metadata(report: Dict[str, Any], request: HttpRequest) -> None:
     report['has_request'] = True
diff --git a/zerver/management/commands/create_user.py b/zerver/management/commands/create_user.py
index 1b6a2dacce..72e8c11497 100644
--- a/zerver/management/commands/create_user.py
+++ b/zerver/management/commands/create_user.py
@@ -77,7 +77,8 @@ parameters, or specify no parameters for interactive user creation.""")
 
         try:
             if options['password_file']:
-                pw = open(options['password_file'], 'r').read()
+                with open(options['password_file'], 'r') as f:
+                    pw = f.read()
             elif options['password']:
                 pw = options['password']
             else:
diff --git a/zerver/tests/test_auth_backends.py b/zerver/tests/test_auth_backends.py
index 2668ea5927..2eb1782ea4 100644
--- a/zerver/tests/test_auth_backends.py
+++ b/zerver/tests/test_auth_backends.py
@@ -3062,7 +3062,8 @@ class TestZulipLDAPUserPopulator(ZulipLDAPTestCase):
     @use_s3_backend
     def test_update_user_avatar_for_s3(self) -> None:
         bucket = create_s3_buckets(settings.S3_AVATAR_BUCKET)[0]
-        test_image_data = open(get_test_image_file('img.png').name, 'rb').read()
+        with open(get_test_image_file('img.png').name, 'rb') as f:
+            test_image_data = f.read()
 
         self.mock_ldap.directory = {
             'uid=hamlet,ou=users,dc=zulip,dc=com': {
diff --git a/zerver/tests/test_bugdown.py b/zerver/tests/test_bugdown.py
index f0e4246449..add925debf 100644
--- a/zerver/tests/test_bugdown.py
+++ b/zerver/tests/test_bugdown.py
@@ -262,8 +262,8 @@ class BugdownTest(ZulipTestCase):
 
     def load_bugdown_tests(self) -> Tuple[Dict[str, Any], List[List[str]]]:
         test_fixtures = {}
-        data_file = open(os.path.join(os.path.dirname(__file__), 'fixtures/markdown_test_cases.json'), 'r')
-        data = ujson.loads('\n'.join(data_file.readlines()))
+        with open(os.path.join(os.path.dirname(__file__), 'fixtures/markdown_test_cases.json'), 'r') as f:
+            data = ujson.loads('\n'.join(f.readlines()))
         for test in data['regular_tests']:
             test_fixtures[test['name']] = test
 
diff --git a/zerver/tests/test_import_export.py b/zerver/tests/test_import_export.py
index 715ea24558..f0bf3ac70d 100644
--- a/zerver/tests/test_import_export.py
+++ b/zerver/tests/test_import_export.py
@@ -301,7 +301,8 @@ class ImportExportTest(ZulipTestCase):
             upload_emoji_image(img_file, '1.png', user_profile)
         with get_test_image_file('img.png') as img_file:
             upload_avatar_image(img_file, user_profile, user_profile)
-        test_image = open(get_test_image_file('img.png').name, 'rb').read()
+        with open(get_test_image_file('img.png').name, 'rb') as f:
+            test_image = f.read()
         message.sender.avatar_source = 'U'
         message.sender.save()
 
@@ -323,7 +324,7 @@ class ImportExportTest(ZulipTestCase):
 
         # Test uploads
         fn = os.path.join(full_data['uploads_dir'], path_id)
-        with open(fn) as f:
+        with open(fn, 'r') as f:
             self.assertEqual(f.read(), 'zulip!')
         records = full_data['uploads_dir_records']
         self.assertEqual(records[0]['path'], path_id)
@@ -340,7 +341,8 @@ class ImportExportTest(ZulipTestCase):
 
         # Test avatars
         fn = os.path.join(full_data['avatar_dir'], original_avatar_path_id)
-        fn_data = open(fn, 'rb').read()
+        with open(fn, 'rb') as fb:
+            fn_data = fb.read()
         self.assertEqual(fn_data, test_image)
         records = full_data['avatar_dir_records']
         record_path = [record['path'] for record in records]
@@ -370,7 +372,7 @@ class ImportExportTest(ZulipTestCase):
         # Test uploads
         fields = attachment_path_id.split('/')
         fn = os.path.join(full_data['uploads_dir'], os.path.join(fields[0], fields[1], fields[2]))
-        with open(fn) as f:
+        with open(fn, 'r') as f:
             self.assertEqual(f.read(), 'zulip!')
         records = full_data['uploads_dir_records']
         self.assertEqual(records[0]['path'], os.path.join(fields[0], fields[1], fields[2]))
@@ -390,7 +392,8 @@ class ImportExportTest(ZulipTestCase):
 
         # Test avatars
         fn = os.path.join(full_data['avatar_dir'], original_avatar_path_id)
-        fn_data = open(fn, 'rb').read()
+        with open(fn, 'rb') as file:
+            fn_data = file.read()
         self.assertEqual(fn_data, test_image)
         records = full_data['avatar_dir_records']
         record_path = [record['path'] for record in records]
@@ -994,7 +997,8 @@ class ImportExportTest(ZulipTestCase):
             do_import_realm(os.path.join(settings.TEST_WORKER_DIR, 'test-export'),
                             'test-zulip')
         imported_realm = Realm.objects.get(string_id='test-zulip')
-        test_image_data = open(get_test_image_file('img.png').name, 'rb').read()
+        with open(get_test_image_file('img.png').name, 'rb') as f:
+            test_image_data = f.read()
 
         # Test attachments
         uploaded_file = Attachment.objects.get(realm=imported_realm)
diff --git a/zerver/tests/test_queue_worker.py b/zerver/tests/test_queue_worker.py
index c486e480cd..a6cc0e4116 100644
--- a/zerver/tests/test_queue_worker.py
+++ b/zerver/tests/test_queue_worker.py
@@ -490,7 +490,8 @@ class WorkerTest(ZulipTestCase):
                     "Problem handling data on queue unreliable_worker")
 
         self.assertEqual(processed, ['good', 'fine', 'back to normal'])
-        line = open(fn).readline().strip()
+        with open(fn, 'r') as f:
+            line = f.readline().strip()
         event = ujson.loads(line.split('\t')[1])
         self.assertEqual(event["type"], 'unexpected behaviour')
 
diff --git a/zerver/tests/test_slack_message_conversion.py b/zerver/tests/test_slack_message_conversion.py
index a3003b497c..28e31ead57 100644
--- a/zerver/tests/test_slack_message_conversion.py
+++ b/zerver/tests/test_slack_message_conversion.py
@@ -24,8 +24,9 @@ class SlackMessageConversion(ZulipTestCase):
 
     def load_slack_message_conversion_tests(self) -> Dict[Any, Any]:
         test_fixtures = {}
-        data_file = open(os.path.join(os.path.dirname(__file__), 'fixtures/slack_message_conversion.json'), 'r')
-        data = ujson.loads('\n'.join(data_file.readlines()))
+        with open(os.path.join(os.path.dirname(__file__),
+                               'fixtures/slack_message_conversion.json'), 'r') as f:
+            data = ujson.loads('\n'.join(f.readlines()))
         for test in data['regular_tests']:
             test_fixtures[test['name']] = test
 
diff --git a/zerver/tests/test_upload.py b/zerver/tests/test_upload.py
index cb0be85fe9..648254e993 100644
--- a/zerver/tests/test_upload.py
+++ b/zerver/tests/test_upload.py
@@ -1558,7 +1558,8 @@ class S3Test(ZulipTestCase):
 
         with get_test_image_file('img.png') as image_file:
             zerver.lib.upload.upload_backend.upload_avatar_image(image_file, user_profile, user_profile)
-        test_image_data = open(get_test_image_file('img.png').name, 'rb').read()
+        with open(get_test_image_file('img.png').name, 'rb') as f:
+            test_image_data = f.read()
         test_medium_image_data = resize_avatar(test_image_data, MEDIUM_AVATAR_SIZE)
 
         original_image_key = bucket.get_key(original_image_path_id)
diff --git a/zerver/views/development/integrations.py b/zerver/views/development/integrations.py
index 6561d5a491..fba4308be9 100644
--- a/zerver/views/development/integrations.py
+++ b/zerver/views/development/integrations.py
@@ -60,7 +60,8 @@ def get_fixtures(request: HttpResponse,
 
     for fixture in os.listdir(fixtures_dir):
         fixture_path = os.path.join(fixtures_dir, fixture)
-        body = open(fixture_path).read()
+        with open(fixture_path, 'r') as f:
+            body = f.read()
         try:
             body = ujson.loads(body)
         except ValueError:
@@ -115,7 +116,8 @@ def send_all_webhook_fixture_messages(request: HttpRequest,
     responses = []
     for fixture in os.listdir(fixtures_dir):
         fixture_path = os.path.join(fixtures_dir, fixture)
-        content = open(fixture_path).read()
+        with open(fixture_path, 'r') as f:
+            content = f.read()
         x = fixture.split(".")
         fixture_name, fixture_format = "".join(_ for _ in x[:-1]), x[-1]
         headers = get_fixture_http_headers(integration_name, fixture_name)