diff --git a/contrib/python/compare_RecordsConfigcc.py b/contrib/python/compare_RecordsConfigcc.py
index 8296ac3d243..2eebce30967 100755
--- a/contrib/python/compare_RecordsConfigcc.py
+++ b/contrib/python/compare_RecordsConfigcc.py
@@ -22,7 +22,7 @@
 try:
     src_dir = sys.argv[1]
 except IndexError:
-    print("Usage: %s [trafficserver_source_dir]" % sys.argv[0])
+    print(f"Usage: {sys.argv[0]} [trafficserver_source_dir]")
     print("Compares values in RecordsConfig.cc with the default records.config file")
     sys.exit(1)
 
@@ -45,7 +45,7 @@
 rc_doc = {}  # documented values
 
 # Process RecordsConfig.cc
-with open("%s/mgmt/RecordsConfig.cc" % src_dir) as fh:
+with open(f"{src_dir}/mgmt/RecordsConfig.cc") as fh:
     cc_re = re.compile(r'\{RECT_(?:CONFIG|LOCAL), "([^"]+)", RECD_([A-Z]+), (.+?), ')
     for line in fh:
         m = cc_re.search(line)
@@ -56,7 +56,7 @@
             rc_cc[m.group(1)] = (m.group(2), value)
 
 # Process records.config.default.in
-with open("%s/configs/records.config.default.in" % src_dir) as fh:
+with open(f"{src_dir}/configs/records.config.default.in") as fh:
     in_re = re.compile(r'(?:CONFIG|LOCAL) (\S+)\s+(\S+)\s+(\S+)')
     for line in fh:
         m = in_re.match(line)
@@ -65,7 +65,7 @@
 
 # Process records.config documentation.
 # eg. .. ts:cv:: CONFIG proxy.config.proxy_binary STRING traffic_server
-with open("%s/doc/admin-guide/files/records.config.en.rst" % src_dir) as fh:
+with open(f"{src_dir}/doc/admin-guide/files/records.config.en.rst") as fh:
     doc_re = re.compile(r'ts:cv:: CONFIG (\S+)\s+(\S+)\s+(\S+)')
     for line in fh:
         m = doc_re.search(line)
@@ -109,4 +109,4 @@
     print()
     print("Stale documentation:")
     for s in sorted(stale):
-        print("\t%s" % (s))
+        print(f"\t{s}")
diff --git a/contrib/python/compare_records_config.py b/contrib/python/compare_records_config.py
index bd610a9b5d1..bd30df084f2 100755
--- a/contrib/python/compare_records_config.py
+++ b/contrib/python/compare_records_config.py
@@ -44,7 +44,7 @@ def parse_records_file(filename):
             try:
                 settings[parts[1]] = parts[3]
             except IndexError:
-                sys.stderr.write("Skipping malformed line: %s\n" % line)
+                sys.stderr.write(f"Skipping malformed line: {line}\n")
                 continue
     return settings
 
@@ -61,7 +61,7 @@ def compare_settings(old, new):
             # Skip predefined values
             continue
         if old[key] != new[key]:
-            print("%s %s -> %s" % (key, old[key], new[key]))
+            print(f"{key} {old[key]} -> {new[key]}")
 
 
 if __name__ == '__main__':
diff --git a/doc/checkvers.py b/doc/checkvers.py
index e0ca9bc66a5..42884452beb 100644
--- a/doc/checkvers.py
+++ b/doc/checkvers.py
@@ -30,21 +30,21 @@
         min_sphinx_version_info = (1, 7, 5)
         min_sphinx_version = '.'.join(str(x) for x in min_sphinx_version_info)
 
-        print('checking for sphinx version >= {0}... '.format(min_sphinx_version), end="")
+        print(f'checking for sphinx version >= {min_sphinx_version}... ', end="")
         # Need at least 1.5.1 to use svg
         # version >= 1.2 guarantees sphinx.version_info is available.
         try:
             import sphinx
 
             if 'version_info' in dir(sphinx):
-                print('Found Sphinx version {0}'.format(sphinx.version_info))
+                print(f'Found Sphinx version {sphinx.version_info}')
             else:
                 version = sphinx.__version__
-                print('Found Sphinx version (old) {0}'.format(sphinx.__version__))
+                print(f'Found Sphinx version (old) {sphinx.__version__}')
                 sphinx.version_info = version.split('.')
 
             if sphinx.version_info < min_sphinx_version_info:
-                print('sphinx version is older than {0}'.format(min_sphinx_version))
+                print(f'sphinx version is older than {min_sphinx_version}')
                 sys.exit(1)
 
         except Exception as e:
diff --git a/doc/conf.py b/doc/conf.py
index 89de61cd34a..5159a82ec1b 100644
--- a/doc/conf.py
+++ b/doc/conf.py
@@ -89,7 +89,7 @@
 
 # General information about the project.
 project = u'Apache Traffic Server'
-copyright = u'{}, dev@trafficserver.apache.org'.format(date.today().year)
+copyright = f'{date.today().year}, dev@trafficserver.apache.org'
 
 # The version info for the project you're documenting, acts as replacement for
 # |version| and |release|, also used in various other places throughout the
diff --git a/plugins/experimental/ssl_session_reuse/tests/plug-load.test.py b/plugins/experimental/ssl_session_reuse/tests/plug-load.test.py
index 10a6468f711..a144e55423d 100644
--- a/plugins/experimental/ssl_session_reuse/tests/plug-load.test.py
+++ b/plugins/experimental/ssl_session_reuse/tests/plug-load.test.py
@@ -37,23 +37,23 @@
 server.addResponse("sessionfile.log", request_header, response_header)
 ts.Disk.records_config.update({
     'proxy.config.diags.debug.enabled': 1,
-    'proxy.config.diags.debug.tags': '{0}'.format(pluginName),
+    'proxy.config.diags.debug.tags': f'{pluginName}',
 })
 
 ts.Disk.plugin_config.AddLine(
-    '# {1}/{0}.so {2}'.format(pluginName, path, configFile)
+    f'# {path}/{pluginName}.so {configFile}'
 )
 ts.Disk.remap_config.AddLine(
-    'map http://www.example.com http://127.0.0.1:{0}'.format(server.Variables.Port)
+    f'map http://www.example.com http://127.0.0.1:{server.Variables.Port}'
 )
 
-goldFile = os.path.join(Test.RunDirectory, "{0}.gold".format(pluginName))
+goldFile = os.path.join(Test.RunDirectory, f"{pluginName}.gold")
 with open(goldFile, 'w+') as jf:
-    jf.write("``loading plugin ``{0}.so``".format(pluginName))
+    jf.write(f"``loading plugin ``{pluginName}.so``")
 
 # call localhost straight
 tr = Test.AddTestRun()
-tr.Processes.Default.Command = 'curl --proxy 127.0.0.1:{0} "http://www.example.com" --verbose'.format(ts.Variables.port)
+tr.Processes.Default.Command = f'curl --proxy 127.0.0.1:{ts.Variables.port} "http://www.example.com" --verbose'
 tr.Processes.Default.ReturnCode = 0
 # time delay as proxy.config.http.wait_for_cache could be broken
 tr.Processes.Default.StartBefore(server, ready=When.PortOpen(server.Variables.Port))
diff --git a/plugins/experimental/traffic_dump/post_process.py b/plugins/experimental/traffic_dump/post_process.py
index 0472cbc0735..2dea30ddbf2 100755
--- a/plugins/experimental/traffic_dump/post_process.py
+++ b/plugins/experimental/traffic_dump/post_process.py
@@ -189,7 +189,7 @@ def write_sessions(sessions, filename, indent):
     new_json["sessions"] = deepcopy(sessions)
     with open(filename, "w") as f:
         json.dump(new_json, f, ensure_ascii=False, indent=indent)
-        logging.debug("{} has {} sessions".format(filename, len(sessions)))
+        logging.debug(f"{filename} has {len(sessions)} sessions")
 
 
 class ParseJSONError(PostProcessError):
@@ -274,11 +274,11 @@ def readAndCombine(replay_dir, num_sessions_per_file, indent, fabricate_proxy_re
             session_count += 1
             transaction_count += len(session["transactions"])
         if len(sessions) >= num_sessions_per_file:
-            write_sessions(sessions, "{}/{}_{}.json".format(out_dir, base_name, batch_count), indent)
+            write_sessions(sessions, f"{out_dir}/{base_name}_{batch_count}.json", indent)
             sessions = []
             batch_count += 1
     if sessions:
-        write_sessions(sessions, "{}/{}_{}.json".format(out_dir, base_name, batch_count), indent)
+        write_sessions(sessions, f"{out_dir}/{base_name}_{batch_count}.json", indent)
 
     return session_count, transaction_count, error_count
 
@@ -409,17 +409,17 @@ def main():
         transaction_count += count_tuple[1]
         for e in count_tuple[2]:
             errors[e] += count_tuple[2][e]
-    summary = "Total {} sessions and {} transactions.".format(session_count, transaction_count)
+    summary = f"Total {session_count} sessions and {transaction_count} transactions."
     logging.info(summary)
     if errors:
         logging.info("Total errors:")
         for e in errors:
-            logging.info("{}: {}".format(e, errors[e]))
+            logging.info(f"{e}: {errors[e]}")
     else:
         logging.info("Total errors: 0")
 
-    with open("{}/summary.txt".format(args.out_dir), "w", encoding="ascii") as f:
-        f.write("{}\n".format(summary))
+    with open(f"{args.out_dir}/summary.txt", "w", encoding="ascii") as f:
+        f.write(f"{summary}\n")
 
 
 if __name__ == "__main__":