diff --git a/.github/workflows/zulip-tests.yml b/.github/workflows/zulip-tests.yml
index 8efb124..cb73728 100644
--- a/.github/workflows/zulip-tests.yml
+++ b/.github/workflows/zulip-tests.yml
@@ -3,7 +3,7 @@ name: build
 on:
   push:
     branches:
-      - master
+      - main
   pull_request:
 
 jobs:
diff --git a/README.md b/README.md
index 6f01bf7..cb296cb 100644
--- a/README.md
+++ b/README.md
@@ -1,8 +1,8 @@
 # Zulip API
 
-[![Build status](https://github.com/zulip/python-zulip-api/workflows/build/badge.svg?branch=master)](
-https://github.com/zulip/python-zulip-api/actions?query=branch%3Amaster+workflow%3Abuild)
-[![Coverage status](https://img.shields.io/codecov/c/github/zulip/python-zulip-api/master.svg)](
+[![Build status](https://github.com/zulip/python-zulip-api/workflows/build/badge.svg)](
+https://github.com/zulip/python-zulip-api/actions?query=branch%3Amain+workflow%3Abuild)
+[![Coverage status](https://img.shields.io/codecov/c/github/zulip/python-zulip-api)](
 https://codecov.io/gh/zulip/python-zulip-api)
 
 This repository contains the source code for Zulip's PyPI packages:
diff --git a/tools/clean-branches b/tools/clean-branches
index 915491b..780f156 100755
--- a/tools/clean-branches
+++ b/tools/clean-branches
@@ -2,9 +2,9 @@
 set -e
 
 # usage: clean-branches
-# Deletes any local branches which are ancestors of origin/master,
+# Deletes any local branches which are ancestors of origin/main,
 # and also any branches in origin which are ancestors of
-# origin/master and are named like $USER-*.
+# origin/main and are named like $USER-*.
 
 # usage: clean-branches --reviews
 # Deletes all the above mentioned branches as well as branches
@@ -18,13 +18,13 @@ fi
 push_args=()
 
 function is_merged {
-    ! git rev-list -n 1 origin/master.."$1" | grep -q .
+    ! git rev-list -n 1 origin/main.."$1" | grep -q .
 }
 
 function clean_ref {
     ref="$1"
     case "$ref" in
-        */master | */HEAD)
+        */main | */HEAD)
             return
             ;;
 
@@ -56,8 +56,8 @@ function clean_ref {
     esac
 }
 
-if [ "$(git symbolic-ref HEAD)" != 'refs/heads/master' ]; then
-    echo "Check out master before you run this script." >&2
+if [ "$(git symbolic-ref HEAD)" != 'refs/heads/main' ]; then
+    echo "Check out main before you run this script." >&2
     exit 1
 fi
 
diff --git a/tools/deploy-branch b/tools/deploy-branch
index 4755f2c..a3838dc 100755
--- a/tools/deploy-branch
+++ b/tools/deploy-branch
@@ -17,7 +17,7 @@ branch_ref=$(git rev-list --max-count=1 "$branch")
 [ $? -ne 0 ] && error_out "Unknown branch: $branch"
 
 if [ "$old_ref" == "$branch_ref" ]; then
-    new_ref=master
+    new_ref=main
 else
     ref_name=$(git describe --all --exact "$old_ref")
     if [ $? -eq 0 ]; then
@@ -31,12 +31,12 @@ fi
 
 git fetch -p
 
-git rebase origin/master "$branch"
-[ $? -ne 0 ] && error_out "Rebase onto origin/master failed"
+git rebase origin/main "$branch"
+[ $? -ne 0 ] && error_out "Rebase onto origin/main failed"
 
-git push . HEAD:master
-git push origin master
-[ $? -ne 0 ] && error_out "Push of master to origin/master failed"
+git push . HEAD:main
+git push origin main
+[ $? -ne 0 ] && error_out "Push of main to origin/main failed"
 
 git checkout "$new_ref"
 git branch -D "$branch"
diff --git a/tools/fetch-rebase-pull-request b/tools/fetch-rebase-pull-request
index ab3fec3..5d9df65 100755
--- a/tools/fetch-rebase-pull-request
+++ b/tools/fetch-rebase-pull-request
@@ -12,6 +12,6 @@ fi
 request_id="$1"
 remote=${2:-"upstream"}
 git fetch "$remote" "pull/$request_id/head"
-git checkout -B "review-${request_id}" $remote/master
+git checkout -B "review-${request_id}" $remote/main
 git reset --hard FETCH_HEAD
 git pull --rebase
diff --git a/tools/lint-commits b/tools/lint-commits
index 87698b6..5de2586 100755
--- a/tools/lint-commits
+++ b/tools/lint-commits
@@ -4,7 +4,7 @@
 # Edited at Line 14 Col 97 (zulip -> python-zulip-api)
 # Please don't edit here; instead update the zulip/zulip copy and then resync this file.
 
-# Lint all commit messages that are newer than upstream/master if running
+# Lint all commit messages that are newer than upstream/main if running
 # locally or the commits in the push or PR Gh-Actions.
 
 # The rules can be found in /.gitlint
@@ -16,9 +16,9 @@ $(git remote -v)
 " =~ '
 '([^[:space:]]*)[[:space:]]*(https://github\.com/|ssh://git@github\.com/|git@github\.com:)"$repository"(\.git|/)?\ \(fetch\)'
 ' ]]; then
-    range="${BASH_REMATCH[1]}/master..HEAD"
+    range="${BASH_REMATCH[1]}/main..HEAD"
 else
-    range="upstream/master..HEAD"
+    range="upstream/main..HEAD"
 fi
 
 commits=$(git log "$range" | wc -l)
diff --git a/tools/review b/tools/review
index cb28232..8dfd56d 100755
--- a/tools/review
+++ b/tools/review
@@ -32,21 +32,21 @@ def check_git_pristine() -> None:
         exit("Git is not pristine:\n" + output)
 
 
-def ensure_on_clean_master() -> None:
+def ensure_on_clean_main() -> None:
     branch = get_git_branch()
-    if branch != "master":
+    if branch != "main":
         exit(f"You are still on a feature branch: {branch}")
     check_git_pristine()
-    run("git fetch upstream master")
-    run("git rebase upstream/master")
+    run("git fetch upstream main")
+    run("git rebase upstream/main")
 
 
 def create_pull_branch(pull_id: int) -> None:
     run("git fetch upstream pull/%d/head" % (pull_id,))
     run(f"git checkout -B review-{pull_id} FETCH_HEAD")
-    run("git rebase upstream/master")
-    run("git log upstream/master.. --oneline")
-    run("git diff upstream/master.. --name-status")
+    run("git rebase upstream/main")
+    run("git log upstream/main.. --oneline")
+    run("git diff upstream/main.. --name-status")
 
     print()
     print("PR: %d" % (pull_id,))
@@ -59,7 +59,7 @@ def review_pr() -> None:
     except Exception:
         exit("please provide an integer pull request id")
 
-    ensure_on_clean_master()
+    ensure_on_clean_main()
     create_pull_branch(pull_id)
 
 
diff --git a/zulip/integrations/bridge_with_irc/irc_mirror_backend.py b/zulip/integrations/bridge_with_irc/irc_mirror_backend.py
index 9ad2fcb..5242ca0 100644
--- a/zulip/integrations/bridge_with_irc/irc_mirror_backend.py
+++ b/zulip/integrations/bridge_with_irc/irc_mirror_backend.py
@@ -38,7 +38,7 @@ class IRCBot(irc.bot.SingleServerIRCBot):
 
     def connect(self, *args: Any, **kwargs: Any) -> None:
         # Taken from
-        # https://github.com/jaraco/irc/blob/master/irc/client_aio.py,
+        # https://github.com/jaraco/irc/blob/main/irc/client_aio.py,
         # in particular the method of AioSimpleIRCClient
         self.c = self.reactor.loop.run_until_complete(self.connection.connect(*args, **kwargs))
         print("Listening now. Please send an IRC message to verify operation")
diff --git a/zulip/integrations/git/post-receive b/zulip/integrations/git/post-receive
index 74b5110..be5522a 100755
--- a/zulip/integrations/git/post-receive
+++ b/zulip/integrations/git/post-receive
@@ -7,7 +7,7 @@
 # stdin in the form
 #  <oldrev> <newrev> <refname>
 # For example:
-#  aa453216d1b3e49e7f6f98441fa56946ddcd6a20 68f7abf4e6f922807889f52bc043ecd31b79f814 refs/heads/master
+#  aa453216d1b3e49e7f6f98441fa56946ddcd6a20 68f7abf4e6f922807889f52bc043ecd31b79f814 refs/heads/main
 
 import os
 import os.path
diff --git a/zulip/integrations/git/zulip_git_config.py b/zulip/integrations/git/zulip_git_config.py
index 0f7fe7a..c9ebe17 100644
--- a/zulip/integrations/git/zulip_git_config.py
+++ b/zulip/integrations/git/zulip_git_config.py
@@ -19,12 +19,12 @@ ZULIP_API_KEY = "0123456789abcdef0123456789abcdef"
 # Returns a dictionary encoding the stream and subject to send the
 # notification to (or None to send no notification).
 #
-# The default code below will send every commit pushed to "master" to
+# The default code below will send every commit pushed to "main" to
 # * stream "commits"
-# * topic "master"
+# * topic "main"
 # And similarly for branch "test-post-receive" (for use when testing).
 def commit_notice_destination(repo: str, branch: str, commit: str) -> Optional[Dict[str, str]]:
-    if branch in ["master", "test-post-receive"]:
+    if branch in ["main", "test-post-receive"]:
         return dict(stream=STREAM_NAME, subject=f"{branch}")
 
     # Return None for cases where you don't want a notice sent
diff --git a/zulip/integrations/hg/zulip_changegroup.py b/zulip/integrations/hg/zulip_changegroup.py
index 21cc4bd..519e186 100755
--- a/zulip/integrations/hg/zulip_changegroup.py
+++ b/zulip/integrations/hg/zulip_changegroup.py
@@ -2,7 +2,7 @@
 
 # Zulip hook for Mercurial changeset pushes.
 #
-# This hook is called when changesets are pushed to the master repository (ie
+# This hook is called when changesets are pushed to the default repository (ie
 # `hg push`). See https://zulip.com/integrations for installation instructions.
 
 import sys
@@ -23,7 +23,7 @@ def format_summary_line(
     information about the changeset and links to the changelog if a
     web URL has been configured:
 
-    Jane Doe <jane@example.com> pushed 1 commit to master (170:e494a5be3393):
+    Jane Doe <jane@example.com> pushed 1 commit to default (170:e494a5be3393):
     """
     revcount = tip - base
     plural = "s" if revcount > 1 else ""
diff --git a/zulip/integrations/openshift/post_deploy b/zulip/integrations/openshift/post_deploy
index 62e4a33..da2bdb9 100755
--- a/zulip/integrations/openshift/post_deploy
+++ b/zulip/integrations/openshift/post_deploy
@@ -28,7 +28,7 @@ client = zulip.Client(
 def get_deployment_details() -> Dict[str, str]:
     # "gear deployments" output example:
     #   Activation time - Deployment ID - Git Ref - Git SHA1
-    #   2017-01-07 15:40:30 -0500 - 9e2b7143 - master - b9ce57c - ACTIVE
+    #   2017-01-07 15:40:30 -0500 - 9e2b7143 - main - b9ce57c - ACTIVE
     dep = subprocess.check_output(["gear", "deployments"], universal_newlines=True).splitlines()[1]
     splits = dep.split(" - ")
 
diff --git a/zulip/integrations/openshift/zulip_openshift_config.py b/zulip/integrations/openshift/zulip_openshift_config.py
index 13d0462..9150d10 100755
--- a/zulip/integrations/openshift/zulip_openshift_config.py
+++ b/zulip/integrations/openshift/zulip_openshift_config.py
@@ -15,12 +15,12 @@ ZULIP_API_KEY = "0123456789abcdef0123456789abcdef"
 # Returns a dictionary encoding the stream and subject to send the
 # notification to (or None to send no notification).
 #
-# The default code below will send every commit pushed to "master" to
+# The default code below will send every commit pushed to "main" to
 # * stream "deployments"
-# * topic "master"
+# * topic "main"
 # And similarly for branch "test-post-receive" (for use when testing).
 def deployment_notice_destination(branch: str) -> Optional[Dict[str, str]]:
-    if branch in ["master", "test-post-receive"]:
+    if branch in ["main", "master", "test-post-receive"]:
         return dict(stream="deployments", subject=f"{branch}")
 
     # Return None for cases where you don't want a notice sent