diff --git a/packaged_helloworld/packaged_helloworld/packaged_helloworld.py b/packaged_helloworld/packaged_helloworld/packaged_helloworld.py
index a8b9aefb8..f027ea423 100644
--- a/packaged_helloworld/packaged_helloworld/packaged_helloworld.py
+++ b/packaged_helloworld/packaged_helloworld/packaged_helloworld.py
@@ -19,10 +19,10 @@ def usage(self) -> str:
         """
 
     def handle_message(self, message: Dict[str, Any], bot_handler: BotHandler) -> None:
-        content = "beep boop"  # type: str
+        content = "beep boop"
         bot_handler.send_reply(message, content)
 
-        emoji_name = "wave"  # type: str
+        emoji_name = "wave"
         bot_handler.react(message, emoji_name)
         return
 
diff --git a/tools/custom_check.py b/tools/custom_check.py
index dea7edc43..f53bbc7ee 100644
--- a/tools/custom_check.py
+++ b/tools/custom_check.py
@@ -1,16 +1,12 @@
 from typing import List
 
-from zulint.custom_rules import RuleList
+from zulint.custom_rules import Rule, RuleList
 
-MYPY = False
-if MYPY:
-    from zulint.custom_rules import Rule
-
-whitespace_rules = [
+whitespace_rules: List[Rule] = [
     # This linter should be first since bash_rules depends on it.
     {"pattern": r"\s+$", "strip": "\n", "description": "Fix trailing whitespace"},
     {"pattern": "\t", "strip": "\n", "description": "Fix tab-based whitespace"},
-]  # type: List[Rule]
+]
 
 markdown_whitespace_rules = list(
     rule for rule in whitespace_rules if rule["pattern"] != r"\s+$"
@@ -129,7 +125,7 @@
     rules=whitespace_rules[0:1],
 )
 
-prose_style_rules = [
+prose_style_rules: List[Rule] = [
     {
         "pattern": r'[^\/\#\-"]([jJ]avascript)',  # exclude usage in hrefs/divs
         "description": "javascript should be spelled JavaScript",
@@ -147,7 +143,7 @@
         "pattern": r"[^-_]botserver(?!rc)|bot server",
         "description": "Use Botserver instead of botserver or Botserver.",
     },
-]  # type: List[Rule]
+]
 
 markdown_docs_length_exclude = {
     "zulip_bots/zulip_bots/bots/converter/doc.md",
diff --git a/tools/deploy b/tools/deploy
index 711d73db8..2b5f1c072 100755
--- a/tools/deploy
+++ b/tools/deploy
@@ -11,12 +11,12 @@ from typing import Any, Callable, Dict, List
 import requests
 from requests import Response
 
-red = "\033[91m"  # type: str
-green = "\033[92m"  # type: str
-end_format = "\033[0m"  # type: str
-bold = "\033[1m"  # type: str
+red = "\033[91m"
+green = "\033[92m"
+end_format = "\033[0m"
+bold = "\033[1m"
 
-bots_dir = ".bots"  # type: str
+bots_dir = ".bots"
 
 
 def pack(options: argparse.Namespace) -> None:
diff --git a/tools/run-mypy b/tools/run-mypy
index 9f0e982a1..a2733a197 100755
--- a/tools/run-mypy
+++ b/tools/run-mypy
@@ -175,7 +175,7 @@ for inpath in force_include:
     try:
         ext = os.path.splitext(inpath)[1].split(".")[1]
     except IndexError:
-        ext = "py"  # type: str
+        ext = "py"
     files_dict[ext].append(inpath)
 
 pyi_files = set(files_dict["pyi"])
diff --git a/zulip/integrations/bridge_with_irc/irc_mirror_backend.py b/zulip/integrations/bridge_with_irc/irc_mirror_backend.py
index 5242ca0d6..a3d2fd7b8 100644
--- a/zulip/integrations/bridge_with_irc/irc_mirror_backend.py
+++ b/zulip/integrations/bridge_with_irc/irc_mirror_backend.py
@@ -21,7 +21,7 @@ def __init__(
         nickserv_password: str = "",
         port: int = 6667,
     ) -> None:
-        self.channel = channel  # type: irc.bot.Channel
+        self.channel: irc.bot.Channel = channel
         self.zulip_client = zulip_client
         self.stream = stream
         self.topic = topic
diff --git a/zulip/integrations/google/get-google-credentials b/zulip/integrations/google/get-google-credentials
index 558366a40..e598f0ccb 100644
--- a/zulip/integrations/google/get-google-credentials
+++ b/zulip/integrations/google/get-google-credentials
@@ -8,9 +8,9 @@ from oauth2client.file import Storage
 try:
     import argparse
 
-    flags = argparse.ArgumentParser(
+    flags: Optional[argparse.Namespace] = argparse.ArgumentParser(
         parents=[tools.argparser]
-    ).parse_args()  # type: Optional[argparse.Namespace]
+    ).parse_args()
 except ImportError:
     flags = None
 
diff --git a/zulip/integrations/google/google-calendar b/zulip/integrations/google/google-calendar
index 311d94f59..424796119 100755
--- a/zulip/integrations/google/google-calendar
+++ b/zulip/integrations/google/google-calendar
@@ -31,10 +31,10 @@ APPLICATION_NAME = "Zulip"
 HOME_DIR = os.path.expanduser("~")
 
 # Our cached view of the calendar, updated periodically.
-events = []  # type: List[Tuple[int, datetime.datetime, str]]
+events: List[Tuple[int, datetime.datetime, str]] = []
 
 # Unique keys for events we've already sent, so we don't remind twice.
-sent = set()  # type: Set[Tuple[int, datetime.datetime]]
+sent: Set[Tuple[int, datetime.datetime]] = set()
 
 sys.path.append(os.path.dirname(__file__))
 
diff --git a/zulip/integrations/jabber/jabber_mirror_backend.py b/zulip/integrations/jabber/jabber_mirror_backend.py
index e70a52eda..05758ba40 100755
--- a/zulip/integrations/jabber/jabber_mirror_backend.py
+++ b/zulip/integrations/jabber/jabber_mirror_backend.py
@@ -87,7 +87,7 @@ def __init__(self, jid: JID, password: str, rooms: List[str]) -> None:
             self.nick = jid.username
             jid.resource = "zulip"
         ClientXMPP.__init__(self, jid, password)
-        self.rooms = set()  # type: Set[str]
+        self.rooms: Set[str] = set()
         self.rooms_to_join = rooms
         self.add_event_handler("session_start", self.session_start)
         self.add_event_handler("message", self.message)
@@ -205,7 +205,7 @@ def nickname_to_jid(self, room: str, nick: str) -> JID:
 class ZulipToJabberBot:
     def __init__(self, zulip_client: Client) -> None:
         self.client = zulip_client
-        self.jabber = None  # type: Optional[JabberToZulipBot]
+        self.jabber: Optional[JabberToZulipBot] = None
 
     def set_jabber_client(self, client: JabberToZulipBot) -> None:
         self.jabber = client
@@ -282,7 +282,7 @@ def get_stream_infos(key: str, method: Callable[[], Dict[str, Any]]) -> Any:
     else:
         stream_infos = get_stream_infos("subscriptions", zulipToJabber.client.get_subscriptions)
 
-    rooms = []  # type: List[str]
+    rooms: List[str] = []
     for stream_info in stream_infos:
         stream = stream_info["name"]
         if stream.endswith("/xmpp"):
diff --git a/zulip/integrations/log2zulip/log2zulip b/zulip/integrations/log2zulip/log2zulip
index 5526c6c9f..2e52ad035 100755
--- a/zulip/integrations/log2zulip/log2zulip
+++ b/zulip/integrations/log2zulip/log2zulip
@@ -105,7 +105,7 @@ def process_logs() -> None:
 
 
 if __name__ == "__main__":
-    parser = zulip.add_default_arguments(argparse.ArgumentParser())  # type: argparse.ArgumentParser
+    parser = zulip.add_default_arguments(argparse.ArgumentParser())
     parser.add_argument("--control-path", default="/etc/log2zulip.conf")
     args = parser.parse_args()
 
diff --git a/zulip/integrations/nagios/nagios-notify-zulip b/zulip/integrations/nagios/nagios-notify-zulip
index 8fd0327e6..ba046d57e 100755
--- a/zulip/integrations/nagios/nagios-notify-zulip
+++ b/zulip/integrations/nagios/nagios-notify-zulip
@@ -8,7 +8,7 @@ VERSION = "0.9"
 # Nagios passes the notification details as command line options.
 # In Nagios, "output" means "first line of output", and "long
 # output" means "other lines of output".
-parser = zulip.add_default_arguments(argparse.ArgumentParser())  # type: argparse.ArgumentParser
+parser = zulip.add_default_arguments(argparse.ArgumentParser())
 parser.add_argument("--output", default="")
 parser.add_argument("--long-output", default="")
 parser.add_argument("--stream", default="nagios")
@@ -17,11 +17,9 @@ for opt in ("type", "host", "service", "state"):
     parser.add_argument("--" + opt)
 opts = parser.parse_args()
 
-client = zulip.Client(
-    config_file=opts.config, client="ZulipNagios/" + VERSION
-)  # type: zulip.Client
+client = zulip.Client(config_file=opts.config, client="ZulipNagios/" + VERSION)
 
-msg = dict(type="stream", to=opts.stream)  # type: Dict[str, Any]
+msg: Dict[str, Any] = dict(type="stream", to=opts.stream)
 
 # Set a subject based on the host or service in question.  This enables
 # threaded discussion of multiple concurrent issues, and provides useful
diff --git a/zulip/integrations/openshift/zulip_openshift_config.py b/zulip/integrations/openshift/zulip_openshift_config.py
index 6d809047c..3ec1c3b7f 100755
--- a/zulip/integrations/openshift/zulip_openshift_config.py
+++ b/zulip/integrations/openshift/zulip_openshift_config.py
@@ -52,7 +52,7 @@ def format_deployment_message(
 
 ## If properly installed, the Zulip API should be in your import
 ## path, but if not, set a custom path below
-ZULIP_API_PATH = None  # type: Optional[str]
+ZULIP_API_PATH: Optional[str] = None
 
 # Set this to your Zulip server's API URI
 ZULIP_SITE = "https://zulip.example.com"
diff --git a/zulip/integrations/perforce/zulip_change-commit.py b/zulip/integrations/perforce/zulip_change-commit.py
index ea7726004..ad434f73e 100755
--- a/zulip/integrations/perforce/zulip_change-commit.py
+++ b/zulip/integrations/perforce/zulip_change-commit.py
@@ -37,11 +37,11 @@
     site=config.ZULIP_SITE,
     api_key=config.ZULIP_API_KEY,
     client="ZulipPerforce/" + __version__,
-)  # type: zulip.Client
+)
 
 try:
-    changelist = int(sys.argv[1])  # type: int
-    changeroot = sys.argv[2]  # type: str
+    changelist = int(sys.argv[1])
+    changeroot = sys.argv[2]
 except IndexError:
     print("Wrong number of arguments.\n\n", end=" ", file=sys.stderr)
     print(__doc__, file=sys.stderr)
@@ -51,11 +51,9 @@
     print(__doc__, file=sys.stderr)
     sys.exit(-1)
 
-metadata = git_p4.p4_describe(changelist)  # type: Dict[str, str]
+metadata: Dict[str, str] = git_p4.p4_describe(changelist)
 
-destination = config.commit_notice_destination(
-    changeroot, changelist
-)  # type: Optional[Dict[str, str]]
+destination: Optional[Dict[str, str]] = config.commit_notice_destination(changeroot, changelist)
 
 if destination is None:
     # Don't forward the notice anywhere
@@ -88,12 +86,12 @@
 ```
 """.format(
     user=metadata["user"], change=change, path=changeroot, desc=metadata["desc"]
-)  # type: str
+)
 
-message_data = {
+message_data: Dict[str, Any] = {
     "type": "stream",
     "to": destination["stream"],
     "subject": destination["subject"],
     "content": message,
-}  # type: Dict[str, Any]
+}
 client.send_message(message_data)
diff --git a/zulip/integrations/rss/rss-bot b/zulip/integrations/rss/rss-bot
index fa9fbb771..a2089f323 100755
--- a/zulip/integrations/rss/rss-bot
+++ b/zulip/integrations/rss/rss-bot
@@ -20,9 +20,9 @@ import feedparser
 
 import zulip
 
-VERSION = "0.9"  # type: str
-RSS_DATA_DIR = os.path.expanduser(os.path.join("~", ".cache", "zulip-rss"))  # type: str
-OLDNESS_THRESHOLD = 30  # type: int
+VERSION = "0.9"
+RSS_DATA_DIR = os.path.expanduser(os.path.join("~", ".cache", "zulip-rss"))
+OLDNESS_THRESHOLD = 30
 
 usage = """Usage: Send summaries of RSS entries for your favorite feeds to Zulip.
 
@@ -48,9 +48,7 @@ stream every 5 minutes is:
 
 */5 * * * * /usr/local/share/zulip/integrations/rss/rss-bot"""
 
-parser = zulip.add_default_arguments(
-    argparse.ArgumentParser(usage)
-)  # type: argparse.ArgumentParser
+parser = zulip.add_default_arguments(argparse.ArgumentParser(usage))
 parser.add_argument(
     "--stream",
     dest="stream",
@@ -94,7 +92,7 @@ parser.add_argument(
     default=False,
 )
 
-opts = parser.parse_args()  # type: Any
+opts = parser.parse_args()
 
 
 def mkdir_p(path: str) -> None:
@@ -115,15 +113,15 @@ except OSError:
     print(f"Unable to store RSS data at {opts.data_dir}.", file=sys.stderr)
     exit(1)
 
-log_file = os.path.join(opts.data_dir, "rss-bot.log")  # type: str
-log_format = "%(asctime)s: %(message)s"  # type: str
+log_file = os.path.join(opts.data_dir, "rss-bot.log")
+log_format = "%(asctime)s: %(message)s"
 logging.basicConfig(format=log_format)
 
-formatter = logging.Formatter(log_format)  # type: logging.Formatter
-file_handler = logging.FileHandler(log_file)  # type: logging.FileHandler
+formatter = logging.Formatter(log_format)
+file_handler = logging.FileHandler(log_file)
 file_handler.setFormatter(formatter)
 
-logger = logging.getLogger(__name__)  # type: logging.Logger
+logger = logging.getLogger(__name__)
 logger.setLevel(logging.DEBUG)
 logger.addHandler(file_handler)
 
@@ -138,7 +136,7 @@ class MLStripper(HTMLParser):
     def __init__(self) -> None:
         super().__init__()
         self.reset()
-        self.fed = []  # type: List[str]
+        self.fed: List[str] = []
 
     def handle_data(self, data: str) -> None:
         self.fed.append(data)
@@ -173,7 +171,7 @@ def elide_subject(subject: str) -> str:
 
 
 def send_zulip(entry: Any, feed_name: str) -> Dict[str, Any]:
-    body = entry.summary  # type: str
+    body: str = entry.summary
     if opts.unwrap:
         body = unwrap_text(body)
 
@@ -182,56 +180,52 @@ def send_zulip(entry: Any, feed_name: str) -> Dict[str, Any]:
         entry.link,
         strip_tags(body),
         entry.link,
-    )  # type: str
+    )
 
     if opts.math:
         content = content.replace("$", "$$")
 
-    message = {
+    message: Dict[str, str] = {
         "type": "stream",
         "to": opts.stream,
         "subject": opts.topic or elide_subject(feed_name),
         "content": content,
-    }  # type: Dict[str, str]
+    }
     return client.send_message(message)
 
 
 try:
     with open(opts.feed_file) as f:
-        feed_urls = [feed.strip() for feed in f.readlines()]  # type: List[str]
+        feed_urls: List[str] = [feed.strip() for feed in f.readlines()]
 except OSError:
     log_error_and_exit(f"Unable to read feed file at {opts.feed_file}.")
 
-client = zulip.Client(
+client: zulip.Client = zulip.Client(
     email=opts.zulip_email,
     api_key=opts.zulip_api_key,
     config_file=opts.zulip_config_file,
     site=opts.zulip_site,
     client="ZulipRSS/" + VERSION,
-)  # type: zulip.Client
+)
 
-first_message = True  # type: bool
+first_message = True
 
 for feed_url in feed_urls:
     feed_file = os.path.join(opts.data_dir, urllib.parse.urlparse(feed_url).netloc)  # Type: str
 
     try:
         with open(feed_file) as f:
-            old_feed_hashes = {
-                line.strip(): True for line in f.readlines()
-            }  # type: Dict[str, bool]
+            old_feed_hashes = {line.strip(): True for line in f.readlines()}
     except OSError:
         old_feed_hashes = {}
 
-    new_hashes = []  # type: List[str]
-    data = feedparser.parse(feed_url)  # type: feedparser.parse
+    new_hashes: List[str] = []
+    data = feedparser.parse(feed_url)
 
     for entry in data.entries:
-        entry_hash = compute_entry_hash(entry)  # type: str
+        entry_hash = compute_entry_hash(entry)
         # An entry has either been published or updated.
-        entry_time = entry.get(
-            "published_parsed", entry.get("updated_parsed")
-        )  # type: Tuple[int, int]
+        entry_time: Tuple[int, int] = entry.get("published_parsed", entry.get("updated_parsed"))
         if (
             entry_time is not None
             and (time.time() - calendar.timegm(entry_time)) > OLDNESS_THRESHOLD * 60 * 60 * 24
@@ -247,9 +241,9 @@ for feed_url in feed_urls:
             # entries in reverse chronological order.
             break
 
-        feed_name = data.feed.title or feed_url  # type: str
+        feed_name: str = data.feed.title or feed_url
 
-        response = send_zulip(entry, feed_name)  # type: Dict[str, Any]
+        response: Dict[str, Any] = send_zulip(entry, feed_name)
         if response["result"] != "success":
             logger.error(f"Error processing {feed_url}")
             logger.error(str(response))
diff --git a/zulip/integrations/svn/post-commit b/zulip/integrations/svn/post-commit
index 4b271d457..6dc2e852e 100755
--- a/zulip/integrations/svn/post-commit
+++ b/zulip/integrations/svn/post-commit
@@ -31,17 +31,17 @@ client = zulip.Client(
     site=config.ZULIP_SITE,
     api_key=config.ZULIP_API_KEY,
     client="ZulipSVN/" + VERSION,
-)  # type: zulip.Client
-svn = pysvn.Client()  # type: pysvn.Client
+)
+svn = pysvn.Client()
 
 path, rev = sys.argv[1:]
 
 # since its a local path, prepend "file://"
 path = "file://" + path
 
-entry = svn.log(path, revision_end=pysvn.Revision(pysvn.opt_revision_kind.number, rev))[
-    0
-]  # type: Dict[str, Any]
+entry: Dict[str, Any] = svn.log(
+    path, revision_end=pysvn.Revision(pysvn.opt_revision_kind.number, rev)
+)[0]
 message = "**{}** committed revision r{} to `{}`.\n\n> {}".format(
     entry["author"], rev, path.split("/")[-1], entry["revprops"]["svn:log"]
 )
@@ -49,10 +49,10 @@ message = "**{}** committed revision r{} to `{}`.\n\n> {}".format(
 destination = config.commit_notice_destination(path, rev)
 
 if destination is not None:
-    message_data = {
+    message_data: Dict[str, Any] = {
         "type": "stream",
         "to": destination["stream"],
         "subject": destination["subject"],
         "content": message,
-    }  # type: Dict[str, Any]
+    }
     client.send_message(message_data)
diff --git a/zulip/integrations/zephyr/check-mirroring b/zulip/integrations/zephyr/check-mirroring
index b2da931f2..d5f9dff56 100755
--- a/zulip/integrations/zephyr/check-mirroring
+++ b/zulip/integrations/zephyr/check-mirroring
@@ -192,8 +192,8 @@ if not actually_subscribed:
     print_status_and_exit(1)
 
 # Prepare keys
-zhkeys = {}  # type: Dict[str, Tuple[str, str]]
-hzkeys = {}  # type: Dict[str, Tuple[str, str]]
+zhkeys: Dict[str, Tuple[str, str]] = {}
+hzkeys: Dict[str, Tuple[str, str]] = {}
 
 
 def gen_key(key_dict: Dict[str, Tuple[str, str]]) -> str:
@@ -313,7 +313,7 @@ def process_keys(content_list: List[str]) -> Tuple[Dict[str, int], Set[str], Set
     # Start by filtering out any keys that might have come from
     # concurrent check-mirroring processes
     content_keys = [key for key in content_list if key in all_keys]
-    key_counts = {}  # type: Dict[str, int]
+    key_counts: Dict[str, int] = {}
     for key in all_keys:
         key_counts[key] = 0
     for key in content_keys:
diff --git a/zulip/integrations/zephyr/zephyr_mirror_backend.py b/zulip/integrations/zephyr/zephyr_mirror_backend.py
index fa7707d3e..0b27110ac 100755
--- a/zulip/integrations/zephyr/zephyr_mirror_backend.py
+++ b/zulip/integrations/zephyr/zephyr_mirror_backend.py
@@ -1107,7 +1107,7 @@ def valid_stream_name(name: str) -> bool:
 
 
 def parse_zephyr_subs(verbose: bool = False) -> Set[Tuple[str, str, str]]:
-    zephyr_subscriptions = set()  # type: Set[Tuple[str, str, str]]
+    zephyr_subscriptions: Set[Tuple[str, str, str]] = set()
     subs_file = os.path.join(os.environ["HOME"], ".zephyr.subs")
     if not os.path.exists(subs_file):
         if verbose:
@@ -1348,7 +1348,7 @@ def die_gracefully(signal: int, frame: FrameType) -> None:
         options.session_path = f"/var/tmp/{options.user}"
 
     if options.forward_from_zulip:
-        child_pid = os.fork()  # type: Optional[int]
+        child_pid: Optional[int] = os.fork()
         if child_pid == 0:
             CURRENT_STATE = States.ZulipToZephyr
             # Run the zulip => zephyr mirror in the child
diff --git a/zulip/tests/__init__.py b/zulip/tests/__init__.py
index 84a60e811..832c764d2 100644
--- a/zulip/tests/__init__.py
+++ b/zulip/tests/__init__.py
@@ -1,4 +1,4 @@
 import pkgutil
 from typing import List
 
-__path__ = pkgutil.extend_path(__path__, __name__)  # type: List[str]
+__path__: List[str] = pkgutil.extend_path(__path__, __name__)
diff --git a/zulip/zulip/__init__.py b/zulip/zulip/__init__.py
index 45c93d656..d32a80404 100644
--- a/zulip/zulip/__init__.py
+++ b/zulip/zulip/__init__.py
@@ -485,7 +485,7 @@ def __init__(
                 "certificate will not be validated, making the "
                 "HTTPS connection potentially insecure"
             )
-            self.tls_verification = False  # type: Union[bool, str]
+            self.tls_verification: Union[bool, str] = False
         elif cert_bundle is not None:
             if not os.path.isfile(cert_bundle):
                 raise ConfigNotFoundError(f"tls bundle '{cert_bundle}' does not exist")
@@ -509,7 +509,7 @@ def __init__(
         self.client_cert = client_cert
         self.client_cert_key = client_cert_key
 
-        self.session = None  # type: Optional[requests.Session]
+        self.session: Optional[requests.Session] = None
 
         self.has_connected = False
 
@@ -527,10 +527,10 @@ def ensure_session(self) -> None:
         # Build a client cert object for requests
         if self.client_cert_key is not None:
             assert self.client_cert is not None  # Otherwise ZulipError near end of __init__
-            client_cert = (
+            client_cert: Union[None, str, Tuple[str, str]] = (
                 self.client_cert,
                 self.client_cert_key,
-            )  # type: Union[None, str, Tuple[str, str]]
+            )
         else:
             client_cert = self.client_cert
 
@@ -602,11 +602,11 @@ def do_api_query(
         self.ensure_session()
         assert self.session is not None
 
-        query_state = {
+        query_state: Dict[str, Any] = {
             "had_error_retry": False,
             "request": request,
             "failures": 0,
-        }  # type: Dict[str, Any]
+        }
 
         def error_retry(error_string: str) -> bool:
             if not self.retry_on_errors or query_state["failures"] >= 10:
diff --git a/zulip/zulip/examples/get-history b/zulip/zulip/examples/get-history
index c77c81b6d..08d269b91 100644
--- a/zulip/zulip/examples/get-history
+++ b/zulip/zulip/examples/get-history
@@ -40,7 +40,7 @@ request = {
     "apply_markdown": False,
 }
 
-all_messages = []  # type: List[Dict[str, Any]]
+all_messages: List[Dict[str, Any]] = []
 found_newest = False
 
 while not found_newest:
diff --git a/zulip/zulip/examples/upload-file b/zulip/zulip/examples/upload-file
index bdb141518..6cb982076 100755
--- a/zulip/zulip/examples/upload-file
+++ b/zulip/zulip/examples/upload-file
@@ -28,7 +28,7 @@ options = parser.parse_args()
 client = zulip.init_from_options(options)
 
 if options.file_path:
-    file = open(options.file_path, "rb")  # type: IO[Any]
+    file: IO[Any] = open(options.file_path, "rb")
 else:
     file = StringIO("This is a test file.")
     file.name = "test.txt"
diff --git a/zulip_bots/zulip_bots/bots/baremetrics/baremetrics.py b/zulip_bots/zulip_bots/bots/baremetrics/baremetrics.py
index c6d303d5f..3ef62a122 100644
--- a/zulip_bots/zulip_bots/bots/baremetrics/baremetrics.py
+++ b/zulip_bots/zulip_bots/bots/baremetrics/baremetrics.py
@@ -241,14 +241,14 @@ def get_subscriptions(self, source_id: str) -> str:
         return "\n".join(response)
 
     def create_plan(self, parameters: List[str]) -> str:
-        data_header = {
+        data_header: Any = {
             "oid": parameters[1],
             "name": parameters[2],
             "currency": parameters[3],
             "amount": int(parameters[4]),
             "interval": parameters[5],
             "interval_count": int(parameters[6]),
-        }  # type: Any
+        }
 
         url = f"https://api.baremetrics.com/v1/{parameters[0]}/plans"
         create_plan_response = requests.post(url, data=data_header, headers=self.auth_header)
diff --git a/zulip_bots/zulip_bots/bots/converter/converter.py b/zulip_bots/zulip_bots/bots/converter/converter.py
index d8725b059..9e23f0742 100644
--- a/zulip_bots/zulip_bots/bots/converter/converter.py
+++ b/zulip_bots/zulip_bots/bots/converter/converter.py
@@ -87,8 +87,8 @@ def get_bot_converter_response(message: Dict[str, str], bot_handler: BotHandler)
                     exponent -= exp
                     unit_to = unit_to[len(key) :]
 
-            uf_to_std = utils.UNITS.get(unit_from, [])  # type: List[Any]
-            ut_to_std = utils.UNITS.get(unit_to, [])  # type: List[Any]
+            uf_to_std: List[Any] = utils.UNITS.get(unit_from, [])
+            ut_to_std: List[Any] = utils.UNITS.get(unit_to, [])
 
             if not uf_to_std:
                 results.append("`" + unit_from + "` is not a valid unit. " + utils.QUICK_HELP)
diff --git a/zulip_bots/zulip_bots/bots/dropbox_share/dropbox_share.py b/zulip_bots/zulip_bots/bots/dropbox_share/dropbox_share.py
index 930ac0ea4..29c9ba11a 100644
--- a/zulip_bots/zulip_bots/bots/dropbox_share/dropbox_share.py
+++ b/zulip_bots/zulip_bots/bots/dropbox_share/dropbox_share.py
@@ -148,7 +148,7 @@ def dbx_ls(client: Any, fn: str) -> str:
 
     try:
         result = client.files_list_folder(fn)
-        files_list = []  # type: List[str]
+        files_list: List[str] = []
         for meta in result.entries:
             files_list += [" - " + URL.format(name=meta.name, path=meta.path_lower)]
 
diff --git a/zulip_bots/zulip_bots/bots/helloworld/helloworld.py b/zulip_bots/zulip_bots/bots/helloworld/helloworld.py
index 79e9437fb..55212a88f 100644
--- a/zulip_bots/zulip_bots/bots/helloworld/helloworld.py
+++ b/zulip_bots/zulip_bots/bots/helloworld/helloworld.py
@@ -16,10 +16,10 @@ def usage(self) -> str:
         """
 
     def handle_message(self, message: Dict[str, Any], bot_handler: BotHandler) -> None:
-        content = "beep boop"  # type: str
+        content = "beep boop"
         bot_handler.send_reply(message, content)
 
-        emoji_name = "wave"  # type: str
+        emoji_name = "wave"
         bot_handler.react(message, emoji_name)
         return
 
diff --git a/zulip_bots/zulip_bots/bots/helloworld/test_helloworld.py b/zulip_bots/zulip_bots/bots/helloworld/test_helloworld.py
index c3cd80480..ccec95c60 100755
--- a/zulip_bots/zulip_bots/bots/helloworld/test_helloworld.py
+++ b/zulip_bots/zulip_bots/bots/helloworld/test_helloworld.py
@@ -2,7 +2,7 @@
 
 
 class TestHelpBot(BotTestCase, DefaultTests):
-    bot_name = "helloworld"  # type: str
+    bot_name: str = "helloworld"
 
     def test_bot(self) -> None:
         dialog = [
diff --git a/zulip_bots/zulip_bots/bots/idonethis/test_idonethis.py b/zulip_bots/zulip_bots/bots/idonethis/test_idonethis.py
index b3399b3c3..9cdbc1089 100644
--- a/zulip_bots/zulip_bots/bots/idonethis/test_idonethis.py
+++ b/zulip_bots/zulip_bots/bots/idonethis/test_idonethis.py
@@ -4,7 +4,7 @@
 
 
 class TestIDoneThisBot(BotTestCase, DefaultTests):
-    bot_name = "idonethis"  # type: str
+    bot_name: str = "idonethis"
 
     def test_create_entry_default_team(self) -> None:
         with self.mock_config_info(
diff --git a/zulip_bots/zulip_bots/bots/link_shortener/link_shortener.py b/zulip_bots/zulip_bots/bots/link_shortener/link_shortener.py
index 39707df16..3e846d6f2 100644
--- a/zulip_bots/zulip_bots/bots/link_shortener/link_shortener.py
+++ b/zulip_bots/zulip_bots/bots/link_shortener/link_shortener.py
@@ -23,7 +23,7 @@ def initialize(self, bot_handler: BotHandler) -> None:
         self.check_api_key(bot_handler)
 
     def check_api_key(self, bot_handler: BotHandler) -> None:
-        test_request_data = self.call_link_shorten_service("www.youtube.com/watch")  # type: Any
+        test_request_data: Any = self.call_link_shorten_service("www.youtube.com/watch")
         try:
             if self.is_invalid_token_error(test_request_data):
                 bot_handler.quit(
diff --git a/zulip_bots/zulip_bots/bots/mention/mention.py b/zulip_bots/zulip_bots/bots/mention/mention.py
index 253dcc5ce..3935f4db3 100644
--- a/zulip_bots/zulip_bots/bots/mention/mention.py
+++ b/zulip_bots/zulip_bots/bots/mention/mention.py
@@ -75,12 +75,12 @@ def get_alert_id(self, keyword: str) -> str:
             "Accept-Version": "1.15",
         }
 
-        create_alert_data = {
+        create_alert_data: Any = {
             "name": keyword,
             "query": {"type": "basic", "included_keywords": [keyword]},
             "languages": ["en"],
             "sources": ["web"],
-        }  # type: Any
+        }
 
         response = requests.post(
             "https://api.mention.net/api/accounts/" + self.account_id + "/alerts",
diff --git a/zulip_bots/zulip_bots/bots/salesforce/salesforce.py b/zulip_bots/zulip_bots/bots/salesforce/salesforce.py
index 87fad94db..ff2aa770d 100644
--- a/zulip_bots/zulip_bots/bots/salesforce/salesforce.py
+++ b/zulip_bots/zulip_bots/bots/salesforce/salesforce.py
@@ -78,7 +78,7 @@ def query_salesforce(
 ) -> str:
     arg = arg.strip()
     qarg = arg.split(" -", 1)[0]
-    split_args = []  # type: List[str]
+    split_args: List[str] = []
     raw_arg = ""
     if len(arg.split(" -", 1)) > 1:
         raw_arg = " -" + arg.split(" -", 1)[1]
@@ -96,10 +96,10 @@ def query_salesforce(
     res = salesforce.query(
         query.format(object_type["fields"], object_type["table"], qarg, limit_num)
     )
-    exclude_keys = []  # type: List[str]
+    exclude_keys: List[str] = []
     if "exclude_keys" in command.keys():
         exclude_keys = command["exclude_keys"]
-    force_keys = []  # type: List[str]
+    force_keys: List[str] = []
     if "force_keys" in command.keys():
         force_keys = command["force_keys"]
     rank_output = False
diff --git a/zulip_bots/zulip_bots/bots/salesforce/test_salesforce.py b/zulip_bots/zulip_bots/bots/salesforce/test_salesforce.py
index 23ab65fe3..63e3afb76 100644
--- a/zulip_bots/zulip_bots/bots/salesforce/test_salesforce.py
+++ b/zulip_bots/zulip_bots/bots/salesforce/test_salesforce.py
@@ -96,7 +96,7 @@ def echo(arg: str, sf: Any, command: Dict[str, Any]) -> str:
 
 
 class TestSalesforceBot(BotTestCase, DefaultTests):
-    bot_name = "salesforce"  # type: str
+    bot_name: str = "salesforce"
 
     def _test(self, test_name: str, message: str, response: str, auth_success: bool = True) -> None:
         with self.mock_config_info(mock_config), mock_salesforce_auth(
diff --git a/zulip_bots/zulip_bots/bots/salesforce/utils.py b/zulip_bots/zulip_bots/bots/salesforce/utils.py
index 313fb43bf..f8a233c38 100644
--- a/zulip_bots/zulip_bots/bots/salesforce/utils.py
+++ b/zulip_bots/zulip_bots/bots/salesforce/utils.py
@@ -3,7 +3,7 @@
 link_query = "SELECT {} FROM {} WHERE Id='{}'"
 default_query = "SELECT {} FROM {} WHERE Name LIKE '%{}%' LIMIT {}"
 
-commands = [
+commands: List[Dict[str, Any]] = [
     {
         "commands": ["search account", "find account", "search accounts", "find accounts"],
         "object": "account",
@@ -41,9 +41,9 @@
         "rank_output": True,
         "force_keys": ["Amount"],
     },
-]  # type: List[Dict[str, Any]]
+]
 
-object_types = {
+object_types: Dict[str, Dict[str, str]] = {
     "account": {
         "fields": "Id, Name, Phone, BillingStreet, BillingCity, BillingState",
         "table": "Account",
@@ -53,4 +53,4 @@
         "fields": "Id, Name, Amount, Probability, StageName, CloseDate",
         "table": "Opportunity",
     },
-}  # type: Dict[str, Dict[str, str]]
+}
diff --git a/zulip_bots/zulip_bots/bots/tictactoe/tictactoe.py b/zulip_bots/zulip_bots/bots/tictactoe/tictactoe.py
index 0ab6298d1..322896428 100644
--- a/zulip_bots/zulip_bots/bots/tictactoe/tictactoe.py
+++ b/zulip_bots/zulip_bots/bots/tictactoe/tictactoe.py
@@ -160,7 +160,7 @@ def computer_move(self, board: Any, player_number: Any) -> Any:
         # there are two blanks and an 2 in each row, column, and diagonal (done in two_blanks).
         # If smarter is False, all blank locations can be chosen.
         if self.smarter:
-            blanks = []  # type: Any
+            blanks: Any = []
             for triplet in self.triplets:
                 result = self.two_blanks(triplet, board)
                 if result:
diff --git a/zulip_bots/zulip_bots/bots/trello/test_trello.py b/zulip_bots/zulip_bots/bots/trello/test_trello.py
index 60af4174d..e2ea302ff 100644
--- a/zulip_bots/zulip_bots/bots/trello/test_trello.py
+++ b/zulip_bots/zulip_bots/bots/trello/test_trello.py
@@ -7,7 +7,7 @@
 
 
 class TestTrelloBot(BotTestCase, DefaultTests):
-    bot_name = "trello"  # type: str
+    bot_name: str = "trello"
 
     def test_bot_responds_to_empty_message(self) -> None:
         with self.mock_config_info(mock_config), patch("requests.get"):
diff --git a/zulip_bots/zulip_bots/bots/trello/trello.py b/zulip_bots/zulip_bots/bots/trello/trello.py
index effb6e44f..b8d7865ac 100644
--- a/zulip_bots/zulip_bots/bots/trello/trello.py
+++ b/zulip_bots/zulip_bots/bots/trello/trello.py
@@ -93,7 +93,7 @@ def get_all_boards(self) -> str:
         return bot_response
 
     def get_board_descs(self, boards: List[str]) -> str:
-        bot_response = []  # type: List[str]
+        bot_response: List[str] = []
         get_board_desc_url = "https://api.trello.com/1/boards/{}/"
         for index, board in enumerate(boards):
             board_desc_response = requests.get(
diff --git a/zulip_bots/zulip_bots/bots/trivia_quiz/test_trivia_quiz.py b/zulip_bots/zulip_bots/bots/trivia_quiz/test_trivia_quiz.py
index 4730a3f3e..231f1a869 100644
--- a/zulip_bots/zulip_bots/bots/trivia_quiz/test_trivia_quiz.py
+++ b/zulip_bots/zulip_bots/bots/trivia_quiz/test_trivia_quiz.py
@@ -15,7 +15,7 @@
 
 
 class TestTriviaQuizBot(BotTestCase, DefaultTests):
-    bot_name = "trivia_quiz"  # type: str
+    bot_name: str = "trivia_quiz"
 
     new_question_response = (
         "\nQ: Which class of animals are newts members of?\n\n"
diff --git a/zulip_bots/zulip_bots/bots/trivia_quiz/trivia_quiz.py b/zulip_bots/zulip_bots/bots/trivia_quiz/trivia_quiz.py
index eeaa0e603..302ecbd09 100644
--- a/zulip_bots/zulip_bots/bots/trivia_quiz/trivia_quiz.py
+++ b/zulip_bots/zulip_bots/bots/trivia_quiz/trivia_quiz.py
@@ -130,13 +130,13 @@ def get_quiz_from_payload(payload: Dict[str, Any]) -> Dict[str, Any]:
     for i in range(3):
         answers[letters[i + 1]] = result["incorrect_answers"][i]
     answers = {letter: fix_quotes(answer) for letter, answer in answers.items()}
-    quiz = dict(
+    quiz: Dict[str, Any] = dict(
         question=fix_quotes(question),
         answers=answers,
         answered_options=[],
         pending=True,
         correct_letter=correct_letter,
-    )  # type: Dict[str, Any]
+    )
     return quiz
 
 
diff --git a/zulip_bots/zulip_bots/bots/youtube/test_youtube.py b/zulip_bots/zulip_bots/bots/youtube/test_youtube.py
index 99655c245..47eb75e03 100644
--- a/zulip_bots/zulip_bots/bots/youtube/test_youtube.py
+++ b/zulip_bots/zulip_bots/bots/youtube/test_youtube.py
@@ -8,11 +8,11 @@
 
 class TestYoutubeBot(BotTestCase, DefaultTests):
     bot_name = "youtube"
-    normal_config = {
+    normal_config: Dict[str, str] = {
         "key": "12345678",
         "number_of_results": "5",
         "video_region": "US",
-    }  # type: Dict[str,str]
+    }
 
     help_content = (
         "*Help for YouTube bot* :robot_face: : \n\n"
diff --git a/zulip_bots/zulip_bots/bots/youtube/youtube.py b/zulip_bots/zulip_bots/bots/youtube/youtube.py
index d9fae791f..646fbf767 100644
--- a/zulip_bots/zulip_bots/bots/youtube/youtube.py
+++ b/zulip_bots/zulip_bots/bots/youtube/youtube.py
@@ -56,7 +56,7 @@ def handle_message(self, message: Dict[str, str], bot_handler: BotHandler) -> No
 
 def search_youtube(query: str, key: str, region: str, max_results: int = 1) -> List[List[str]]:
     videos = []
-    params = {
+    params: Dict[str, Union[str, int]] = {
         "part": "id,snippet",
         "maxResults": max_results,
         "key": key,
@@ -64,7 +64,7 @@ def search_youtube(query: str, key: str, region: str, max_results: int = 1) -> L
         "alt": "json",
         "type": "video",
         "regionCode": region,
-    }  # type: Dict[str, Union[str, int]]
+    }
 
     url = "https://www.googleapis.com/youtube/v3/search"
     try:
@@ -98,7 +98,7 @@ def get_bot_response(
     key = config_info["key"]
     max_results = int(config_info["number_of_results"])
     region = config_info["video_region"]
-    video_list = []  # type: List[List[str]]
+    video_list: List[List[str]] = []
     try:
         if query == "" or query is None:
             return YoutubeHandler.help_content
diff --git a/zulip_bots/zulip_bots/game_handler.py b/zulip_bots/zulip_bots/game_handler.py
index 437749611..dc4a92d76 100644
--- a/zulip_bots/zulip_bots/game_handler.py
+++ b/zulip_bots/zulip_bots/game_handler.py
@@ -55,17 +55,17 @@ def __init__(
         self.is_single_player = self.min_players == self.max_players == 1
         self.supports_computer = supports_computer
         self.gameMessageHandler = gameMessageHandler()
-        self.invites = {}  # type: Dict[str, Dict[str, str]]
-        self.instances = {}  # type: Dict[str, Any]
-        self.user_cache = {}  # type: Dict[str, Dict[str, Any]]
-        self.pending_subject_changes = []  # type: List[str]
+        self.invites: Dict[str, Dict[str, str]] = {}
+        self.instances: Dict[str, Any] = {}
+        self.user_cache: Dict[str, Dict[str, Any]] = {}
+        self.pending_subject_changes: List[str] = []
         self.stream = "games"
         self.rules = rules
 
     # Values are [won, lost, drawn, total] new values can be added, but MUST be added to the end of the list.
     def add_user_statistics(self, user: str, values: Dict[str, int]) -> None:
         self.get_user_cache()
-        current_values = {}  # type: Dict[str, int]
+        current_values: Dict[str, int] = {}
         if "stats" in self.get_user_by_email(user).keys():
             current_values = self.user_cache[user]["stats"]
         for key, value in values.items():
@@ -570,7 +570,7 @@ def join_game(self, game_id: str, user_email: str, message: Dict[str, Any] = {})
 
     def get_players(self, game_id: str, parameter: str = "a") -> List[str]:
         if game_id in self.invites.keys():
-            players = []  # type: List[str]
+            players: List[str] = []
             if (
                 self.invites[game_id]["subject"] == "###private###" and "p" in parameter
             ) or "p" not in parameter:
@@ -587,7 +587,7 @@ def get_players(self, game_id: str, parameter: str = "a") -> List[str]:
         return []
 
     def get_game_info(self, game_id: str) -> Dict[str, Any]:
-        game_info = {}  # type: Dict[str, Any]
+        game_info: Dict[str, Any] = {}
         if game_id in self.instances.keys():
             instance = self.instances[game_id]
             game_info = {
@@ -855,8 +855,8 @@ def __init__(
         self.model = deepcopy(self.gameAdapter.model())
         self.board = self.model.current_board
         self.turn = random.randrange(0, len(players)) - 1
-        self.current_draw = {}  # type: Dict[str, bool]
-        self.current_messages = []  # type: List[str]
+        self.current_draw: Dict[str, bool] = {}
+        self.current_messages: List[str] = []
         self.is_changing_subject = False
 
     def start(self) -> None:
diff --git a/zulip_bots/zulip_bots/lib.py b/zulip_bots/zulip_bots/lib.py
index 48510a7a0..412477845 100644
--- a/zulip_bots/zulip_bots/lib.py
+++ b/zulip_bots/zulip_bots/lib.py
@@ -53,7 +53,7 @@ class RateLimit:
     def __init__(self, message_limit: int, interval_limit: int) -> None:
         self.message_limit = message_limit
         self.interval_limit = interval_limit
-        self.message_list = []  # type: List[float]
+        self.message_list: List[float] = []
         self.error_message = "-----> !*!*!*MESSAGE RATE LIMIT REACHED, EXITING*!*!*! <-----\n"
         "Is your bot trapped in an infinite loop by reacting to its own messages?"
 
diff --git a/zulip_bots/zulip_bots/test_file_utils.py b/zulip_bots/zulip_bots/test_file_utils.py
index ff1ee1e71..3fbdaf970 100644
--- a/zulip_bots/zulip_bots/test_file_utils.py
+++ b/zulip_bots/zulip_bots/test_file_utils.py
@@ -19,7 +19,7 @@ def get_bot_message_handler(bot_name: str) -> Any:
     # handler class. Eventually, we want bot's handler classes to
     # inherit from a common prototype specifying the handle_message
     # function.
-    lib_module = import_module("zulip_bots.bots.{bot}.{bot}".format(bot=bot_name))  # type: Any
+    lib_module: Any = import_module("zulip_bots.bots.{bot}.{bot}".format(bot=bot_name))
     return lib_module.handler_class()
 
 
diff --git a/zulip_bots/zulip_bots/test_lib.py b/zulip_bots/zulip_bots/test_lib.py
index 778b325d2..a03cf0fef 100755
--- a/zulip_bots/zulip_bots/test_lib.py
+++ b/zulip_bots/zulip_bots/test_lib.py
@@ -18,7 +18,7 @@ def __init__(self) -> None:
         self.reset_transcript()
 
     def reset_transcript(self) -> None:
-        self.transcript = []  # type: List[Tuple[str, Dict[str, Any]]]
+        self.transcript: List[Tuple[str, Dict[str, Any]]] = []
 
     def identity(self) -> BotIdentity:
         return BotIdentity(self.full_name, self.email)
diff --git a/zulip_botserver/tests/__init__.py b/zulip_botserver/tests/__init__.py
index 84a60e811..832c764d2 100644
--- a/zulip_botserver/tests/__init__.py
+++ b/zulip_botserver/tests/__init__.py
@@ -1,4 +1,4 @@
 import pkgutil
 from typing import List
 
-__path__ = pkgutil.extend_path(__path__, __name__)  # type: List[str]
+__path__: List[str] = pkgutil.extend_path(__path__, __name__)
diff --git a/zulip_botserver/zulip_botserver/server.py b/zulip_botserver/zulip_botserver/server.py
index 100bc1d16..85f49d0b6 100644
--- a/zulip_botserver/zulip_botserver/server.py
+++ b/zulip_botserver/zulip_botserver/server.py
@@ -31,7 +31,7 @@ def read_config_section(parser: configparser.ConfigParser, section: str) -> Dict
 
 
 def read_config_from_env_vars(bot_name: Optional[str] = None) -> Dict[str, Dict[str, str]]:
-    bots_config = {}  # type: Dict[str, Dict[str, str]]
+    bots_config: Dict[str, Dict[str, str]] = {}
     json_config = os.environ.get("ZULIP_BOTSERVER_CONFIG")
 
     if json_config is None:
@@ -67,7 +67,7 @@ def read_config_file(
 ) -> Dict[str, Dict[str, str]]:
     parser = parse_config_file(config_file_path)
 
-    bots_config = {}  # type: Dict[str, Dict[str, str]]
+    bots_config: Dict[str, Dict[str, str]] = {}
     if bot_name is None:
         bots_config = {
             section: read_config_section(parser, section) for section in parser.sections()
@@ -173,7 +173,7 @@ def init_message_handlers(
 
 
 app = Flask(__name__)
-bots_config = {}  # type: Dict[str, Dict[str, str]]
+bots_config: Dict[str, Dict[str, str]] = {}
 
 
 @app.route("/", methods=["POST"])