diff --git a/changelog.d/7813.misc b/changelog.d/7813.misc
new file mode 100644
index 0000000000..f3005cfd27
--- /dev/null
+++ b/changelog.d/7813.misc
@@ -0,0 +1 @@
+Add type hints to the http server code and remove an unused parameter.
diff --git a/synapse/http/server.py b/synapse/http/server.py
index 2b35f86066..cff49202f4 100644
--- a/synapse/http/server.py
+++ b/synapse/http/server.py
@@ -217,7 +217,7 @@ class _AsyncResource(resource.Resource, metaclass=abc.ABCMeta):
         return NOT_DONE_YET
 
     @wrap_async_request_handler
-    async def _async_render_wrapper(self, request):
+    async def _async_render_wrapper(self, request: SynapseRequest):
         """This is a wrapper that delegates to `_async_render` and handles
         exceptions, return values, metrics, etc.
         """
@@ -237,7 +237,7 @@ class _AsyncResource(resource.Resource, metaclass=abc.ABCMeta):
             f = failure.Failure()
             self._send_error_response(f, request)
 
-    async def _async_render(self, request):
+    async def _async_render(self, request: Request):
         """Delegates to `_async_render_<METHOD>` methods, or returns a 400 if
         no appropriate method exists. Can be overriden in sub classes for
         different routing.
@@ -278,7 +278,7 @@ class DirectServeJsonResource(_AsyncResource):
     """
 
     def _send_response(
-        self, request, code, response_object,
+        self, request: Request, code: int, response_object: Any,
     ):
         """Implements _AsyncResource._send_response
         """
@@ -507,14 +507,29 @@ class RootOptionsRedirectResource(OptionsResource, RootRedirect):
 
 
 def respond_with_json(
-    request,
-    code,
-    json_object,
-    send_cors=False,
-    response_code_message=None,
-    pretty_print=False,
-    canonical_json=True,
+    request: Request,
+    code: int,
+    json_object: Any,
+    send_cors: bool = False,
+    pretty_print: bool = False,
+    canonical_json: bool = True,
 ):
+    """Sends encoded JSON in response to the given request.
+
+    Args:
+        request: The http request to respond to.
+        code: The HTTP response code.
+        json_object: The object to serialize to JSON.
+        send_cors: Whether to send Cross-Origin Resource Sharing headers
+            https://fetch.spec.whatwg.org/#http-cors-protocol
+        pretty_print: Whether to include indentation and line-breaks in the
+            resulting JSON bytes.
+        canonical_json: Whether to use the canonicaljson algorithm when encoding
+            the JSON bytes.
+
+    Returns:
+        twisted.web.server.NOT_DONE_YET if the request is still active.
+    """
     # could alternatively use request.notifyFinish() and flip a flag when
     # the Deferred fires, but since the flag is RIGHT THERE it seems like
     # a waste.
@@ -522,7 +537,7 @@ def respond_with_json(
         logger.warning(
             "Not sending response to request %s, already disconnected.", request
         )
-        return
+        return None
 
     if pretty_print:
         json_bytes = encode_pretty_printed_json(json_object) + b"\n"
@@ -533,30 +548,26 @@ def respond_with_json(
         else:
             json_bytes = json.dumps(json_object).encode("utf-8")
 
-    return respond_with_json_bytes(
-        request,
-        code,
-        json_bytes,
-        send_cors=send_cors,
-        response_code_message=response_code_message,
-    )
+    return respond_with_json_bytes(request, code, json_bytes, send_cors=send_cors)
 
 
 def respond_with_json_bytes(
-    request, code, json_bytes, send_cors=False, response_code_message=None
+    request: Request, code: int, json_bytes: bytes, send_cors: bool = False,
 ):
     """Sends encoded JSON in response to the given request.
 
     Args:
-        request (twisted.web.http.Request): The http request to respond to.
-        code (int): The HTTP response code.
-        json_bytes (bytes): The json bytes to use as the response body.
-        send_cors (bool): Whether to send Cross-Origin Resource Sharing headers
+        request: The http request to respond to.
+        code: The HTTP response code.
+        json_bytes: The json bytes to use as the response body.
+        send_cors: Whether to send Cross-Origin Resource Sharing headers
             https://fetch.spec.whatwg.org/#http-cors-protocol
-    Returns:
-        twisted.web.server.NOT_DONE_YET"""
 
-    request.setResponseCode(code, message=response_code_message)
+    Returns:
+        twisted.web.server.NOT_DONE_YET if the request is still active.
+    """
+
+    request.setResponseCode(code)
     request.setHeader(b"Content-Type", b"application/json")
     request.setHeader(b"Content-Length", b"%d" % (len(json_bytes),))
     request.setHeader(b"Cache-Control", b"no-cache, no-store, must-revalidate")
@@ -573,12 +584,12 @@ def respond_with_json_bytes(
     return NOT_DONE_YET
 
 
-def set_cors_headers(request):
-    """Set the CORs headers so that javascript running in a web browsers can
+def set_cors_headers(request: Request):
+    """Set the CORS headers so that javascript running in a web browsers can
     use this API
 
     Args:
-        request (twisted.web.http.Request): The http request to add CORs to.
+        request: The http request to add CORS to.
     """
     request.setHeader(b"Access-Control-Allow-Origin", b"*")
     request.setHeader(
@@ -643,7 +654,7 @@ def set_clickjacking_protection_headers(request: Request):
     request.setHeader(b"Content-Security-Policy", b"frame-ancestors 'none';")
 
 
-def finish_request(request):
+def finish_request(request: Request):
     """ Finish writing the response to the request.
 
     Twisted throws a RuntimeException if the connection closed before the
@@ -662,7 +673,7 @@ def finish_request(request):
         logger.info("Connection disconnected before response was written: %r", e)
 
 
-def _request_user_agent_is_curl(request):
+def _request_user_agent_is_curl(request: Request) -> bool:
     user_agents = request.requestHeaders.getRawHeaders(b"User-Agent", default=[])
     for user_agent in user_agents:
         if b"curl" in user_agent: