diff --git a/changelog.d/7219.misc b/changelog.d/7219.misc
new file mode 100644
index 000000000000..4af5da86463e
--- /dev/null
+++ b/changelog.d/7219.misc
@@ -0,0 +1 @@
+Add typing information to federation server code.
diff --git a/synapse/federation/federation_server.py b/synapse/federation/federation_server.py
index 89d521bc3199..77d0202f750e 100644
--- a/synapse/federation/federation_server.py
+++ b/synapse/federation/federation_server.py
@@ -15,7 +15,7 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 import logging
-from typing import Dict
+from typing import Any, Callable, Dict, List, Match, Optional, Tuple
 
 import six
 from six import iteritems
@@ -38,6 +38,7 @@
     UnsupportedRoomVersionError,
 )
 from synapse.api.room_versions import KNOWN_ROOM_VERSIONS
+from synapse.events import EventBase
 from synapse.federation.federation_base import FederationBase, event_from_pdu_json
 from synapse.federation.persistence import TransactionActions
 from synapse.federation.units import Edu, Transaction
@@ -94,7 +95,9 @@ def __init__(self, hs):
         # come in waves.
         self._state_resp_cache = ResponseCache(hs, "state_resp", timeout_ms=30000)
 
-    async def on_backfill_request(self, origin, room_id, versions, limit):
+    async def on_backfill_request(
+        self, origin: str, room_id: str, versions: List[str], limit: int
+    ) -> Tuple[int, Dict[str, Any]]:
         with (await self._server_linearizer.queue((origin, room_id))):
             origin_host, _ = parse_server_name(origin)
             await self.check_server_matches_acl(origin_host, room_id)
@@ -107,23 +110,25 @@ async def on_backfill_request(self, origin, room_id, versions, limit):
 
         return 200, res
 
-    async def on_incoming_transaction(self, origin, transaction_data):
+    async def on_incoming_transaction(
+        self, origin: str, transaction_data: Dict[str, Any]
+    ) -> Tuple[int, Dict[str, Any]]:
         # keep this as early as possible to make the calculated origin ts as
         # accurate as possible.
         request_time = self._clock.time_msec()
 
         transaction = Transaction(**transaction_data)
 
-        if not transaction.transaction_id:
+        if not transaction.transaction_id:  # type: ignore
             raise Exception("Transaction missing transaction_id")
 
-        logger.debug("[%s] Got transaction", transaction.transaction_id)
+        logger.debug("[%s] Got transaction", transaction.transaction_id)  # type: ignore
 
         # use a linearizer to ensure that we don't process the same transaction
         # multiple times in parallel.
         with (
             await self._transaction_linearizer.queue(
-                (origin, transaction.transaction_id)
+                (origin, transaction.transaction_id)  # type: ignore
             )
         ):
             result = await self._handle_incoming_transaction(
@@ -132,31 +137,33 @@ async def on_incoming_transaction(self, origin, transaction_data):
 
         return result
 
-    async def _handle_incoming_transaction(self, origin, transaction, request_time):
+    async def _handle_incoming_transaction(
+        self, origin: str, transaction: Transaction, request_time: int
+    ) -> Tuple[int, Dict[str, Any]]:
         """ Process an incoming transaction and return the HTTP response
 
         Args:
-            origin (unicode): the server making the request
-            transaction (Transaction): incoming transaction
-            request_time (int): timestamp that the HTTP request arrived at
+            origin: the server making the request
+            transaction: incoming transaction
+            request_time: timestamp that the HTTP request arrived at
 
         Returns:
-            Deferred[(int, object)]: http response code and body
+            HTTP response code and body
         """
         response = await self.transaction_actions.have_responded(origin, transaction)
 
         if response:
             logger.debug(
                 "[%s] We've already responded to this request",
-                transaction.transaction_id,
+                transaction.transaction_id,  # type: ignore
             )
             return response
 
-        logger.debug("[%s] Transaction is new", transaction.transaction_id)
+        logger.debug("[%s] Transaction is new", transaction.transaction_id)  # type: ignore
 
         # Reject if PDU count > 50 or EDU count > 100
-        if len(transaction.pdus) > 50 or (
-            hasattr(transaction, "edus") and len(transaction.edus) > 100
+        if len(transaction.pdus) > 50 or (  # type: ignore
+            hasattr(transaction, "edus") and len(transaction.edus) > 100  # type: ignore
         ):
 
             logger.info("Transaction PDU or EDU count too large. Returning 400")
@@ -204,13 +211,13 @@ async def _handle_pdus_in_txn(
             report back to the sending server.
         """
 
-        received_pdus_counter.inc(len(transaction.pdus))
+        received_pdus_counter.inc(len(transaction.pdus))  # type: ignore
 
         origin_host, _ = parse_server_name(origin)
 
-        pdus_by_room = {}
+        pdus_by_room = {}  # type: Dict[str, List[EventBase]]
 
-        for p in transaction.pdus:
+        for p in transaction.pdus:  # type: ignore
             if "unsigned" in p:
                 unsigned = p["unsigned"]
                 if "age" in unsigned:
@@ -254,7 +261,7 @@ async def _handle_pdus_in_txn(
         # require callouts to other servers to fetch missing events), but
         # impose a limit to avoid going too crazy with ram/cpu.
 
-        async def process_pdus_for_room(room_id):
+        async def process_pdus_for_room(room_id: str):
             logger.debug("Processing PDUs for %s", room_id)
             try:
                 await self.check_server_matches_acl(origin_host, room_id)
@@ -310,7 +317,9 @@ async def _process_edu(edu_dict):
             TRANSACTION_CONCURRENCY_LIMIT,
         )
 
-    async def on_context_state_request(self, origin, room_id, event_id):
+    async def on_context_state_request(
+        self, origin: str, room_id: str, event_id: str
+    ) -> Tuple[int, Dict[str, Any]]:
         origin_host, _ = parse_server_name(origin)
         await self.check_server_matches_acl(origin_host, room_id)
 
@@ -338,7 +347,9 @@ async def on_context_state_request(self, origin, room_id, event_id):
 
         return 200, resp
 
-    async def on_state_ids_request(self, origin, room_id, event_id):
+    async def on_state_ids_request(
+        self, origin: str, room_id: str, event_id: str
+    ) -> Tuple[int, Dict[str, Any]]:
         if not event_id:
             raise NotImplementedError("Specify an event")
 
@@ -354,7 +365,9 @@ async def on_state_ids_request(self, origin, room_id, event_id):
 
         return 200, {"pdu_ids": state_ids, "auth_chain_ids": auth_chain_ids}
 
-    async def _on_context_state_request_compute(self, room_id, event_id):
+    async def _on_context_state_request_compute(
+        self, room_id: str, event_id: str
+    ) -> Dict[str, list]:
         if event_id:
             pdus = await self.handler.get_state_for_pdu(room_id, event_id)
         else:
@@ -367,7 +380,7 @@ async def _on_context_state_request_compute(self, room_id, event_id):
             "auth_chain": [pdu.get_pdu_json() for pdu in auth_chain],
         }
 
-    async def on_pdu_request(self, origin, event_id):
+    async def on_pdu_request(self, origin: str, event_id: str) -> Tuple[int, str]:
         pdu = await self.handler.get_persisted_pdu(origin, event_id)
 
         if pdu:
@@ -375,12 +388,16 @@ async def on_pdu_request(self, origin, event_id):
         else:
             return 404, ""
 
-    async def on_query_request(self, query_type, args):
+    async def on_query_request(
+        self, query_type: str, args: Dict[str, str]
+    ) -> Tuple[int, Dict[str, Any]]:
         received_queries_counter.labels(query_type).inc()
         resp = await self.registry.on_query(query_type, args)
         return 200, resp
 
-    async def on_make_join_request(self, origin, room_id, user_id, supported_versions):
+    async def on_make_join_request(
+        self, origin: str, room_id: str, user_id: str, supported_versions: List[str]
+    ) -> Dict[str, Any]:
         origin_host, _ = parse_server_name(origin)
         await self.check_server_matches_acl(origin_host, room_id)
 
@@ -397,7 +414,7 @@ async def on_make_join_request(self, origin, room_id, user_id, supported_version
 
     async def on_invite_request(
         self, origin: str, content: JsonDict, room_version_id: str
-    ):
+    ) -> Dict[str, Any]:
         room_version = KNOWN_ROOM_VERSIONS.get(room_version_id)
         if not room_version:
             raise SynapseError(
@@ -414,7 +431,9 @@ async def on_invite_request(
         time_now = self._clock.time_msec()
         return {"event": ret_pdu.get_pdu_json(time_now)}
 
-    async def on_send_join_request(self, origin, content, room_id):
+    async def on_send_join_request(
+        self, origin: str, content: JsonDict, room_id: str
+    ) -> Dict[str, Any]:
         logger.debug("on_send_join_request: content: %s", content)
 
         room_version = await self.store.get_room_version(room_id)
@@ -434,7 +453,9 @@ async def on_send_join_request(self, origin, content, room_id):
             "auth_chain": [p.get_pdu_json(time_now) for p in res_pdus["auth_chain"]],
         }
 
-    async def on_make_leave_request(self, origin, room_id, user_id):
+    async def on_make_leave_request(
+        self, origin: str, room_id: str, user_id: str
+    ) -> Dict[str, Any]:
         origin_host, _ = parse_server_name(origin)
         await self.check_server_matches_acl(origin_host, room_id)
         pdu = await self.handler.on_make_leave_request(origin, room_id, user_id)
@@ -444,7 +465,9 @@ async def on_make_leave_request(self, origin, room_id, user_id):
         time_now = self._clock.time_msec()
         return {"event": pdu.get_pdu_json(time_now), "room_version": room_version}
 
-    async def on_send_leave_request(self, origin, content, room_id):
+    async def on_send_leave_request(
+        self, origin: str, content: JsonDict, room_id: str
+    ) -> dict:
         logger.debug("on_send_leave_request: content: %s", content)
 
         room_version = await self.store.get_room_version(room_id)
@@ -460,7 +483,9 @@ async def on_send_leave_request(self, origin, content, room_id):
         await self.handler.on_send_leave_request(origin, pdu)
         return {}
 
-    async def on_event_auth(self, origin, room_id, event_id):
+    async def on_event_auth(
+        self, origin: str, room_id: str, event_id: str
+    ) -> Tuple[int, Dict[str, Any]]:
         with (await self._server_linearizer.queue((origin, room_id))):
             origin_host, _ = parse_server_name(origin)
             await self.check_server_matches_acl(origin_host, room_id)
@@ -471,15 +496,21 @@ async def on_event_auth(self, origin, room_id, event_id):
         return 200, res
 
     @log_function
-    def on_query_client_keys(self, origin, content):
-        return self.on_query_request("client_keys", content)
-
-    async def on_query_user_devices(self, origin: str, user_id: str):
+    async def on_query_client_keys(
+        self, origin: str, content: Dict[str, str]
+    ) -> Tuple[int, Dict[str, Any]]:
+        return await self.on_query_request("client_keys", content)
+
+    async def on_query_user_devices(
+        self, origin: str, user_id: str
+    ) -> Tuple[int, Dict[str, Any]]:
         keys = await self.device_handler.on_federation_query_user_devices(user_id)
         return 200, keys
 
     @trace
-    async def on_claim_client_keys(self, origin, content):
+    async def on_claim_client_keys(
+        self, origin: str, content: Dict[str, Any]
+    ) -> Dict[str, Any]:
         query = []
         for user_id, device_keys in content.get("one_time_keys", {}).items():
             for device_id, algorithm in device_keys.items():
@@ -488,7 +519,7 @@ async def on_claim_client_keys(self, origin, content):
         log_kv({"message": "Claiming one time keys.", "user, device pairs": query})
         results = await self.store.claim_e2e_one_time_keys(query)
 
-        json_result = {}
+        json_result = {}  # type: Dict[str, Dict[str, dict]]
         for user_id, device_keys in results.items():
             for device_id, keys in device_keys.items():
                 for key_id, json_bytes in keys.items():
@@ -511,8 +542,13 @@ async def on_claim_client_keys(self, origin, content):
         return {"one_time_keys": json_result}
 
     async def on_get_missing_events(
-        self, origin, room_id, earliest_events, latest_events, limit
-    ):
+        self,
+        origin: str,
+        room_id: str,
+        earliest_events: List[str],
+        latest_events: List[str],
+        limit: int,
+    ) -> Dict[str, list]:
         with (await self._server_linearizer.queue((origin, room_id))):
             origin_host, _ = parse_server_name(origin)
             await self.check_server_matches_acl(origin_host, room_id)
@@ -541,11 +577,11 @@ async def on_get_missing_events(
         return {"events": [ev.get_pdu_json(time_now) for ev in missing_events]}
 
     @log_function
-    def on_openid_userinfo(self, token):
+    def on_openid_userinfo(self, token: str) -> Optional[str]:
         ts_now_ms = self._clock.time_msec()
         return self.store.get_user_id_for_open_id_token(token, ts_now_ms)
 
-    def _transaction_from_pdus(self, pdu_list):
+    def _transaction_from_pdus(self, pdu_list: List[EventBase]) -> Transaction:
         """Returns a new Transaction containing the given PDUs suitable for
         transmission.
         """
@@ -558,7 +594,7 @@ def _transaction_from_pdus(self, pdu_list):
             destination=None,
         )
 
-    async def _handle_received_pdu(self, origin, pdu):
+    async def _handle_received_pdu(self, origin: str, pdu: EventBase) -> None:
         """ Process a PDU received in a federation /send/ transaction.
 
         If the event is invalid, then this method throws a FederationError.
@@ -579,10 +615,8 @@ async def _handle_received_pdu(self, origin, pdu):
         until we try to backfill across the discontinuity.
 
         Args:
-            origin (str): server which sent the pdu
-            pdu (FrozenEvent): received pdu
-
-        Returns (Deferred): completes with None
+            origin: server which sent the pdu
+            pdu: received pdu
 
         Raises: FederationError if the signatures / hash do not match, or
             if the event was unacceptable for any other reason (eg, too large,
@@ -625,25 +659,27 @@ def __str__(self):
         return "<ReplicationLayer(%s)>" % self.server_name
 
     async def exchange_third_party_invite(
-        self, sender_user_id, target_user_id, room_id, signed
+        self, sender_user_id: str, target_user_id: str, room_id: str, signed: Dict
     ):
         ret = await self.handler.exchange_third_party_invite(
             sender_user_id, target_user_id, room_id, signed
         )
         return ret
 
-    async def on_exchange_third_party_invite_request(self, room_id, event_dict):
+    async def on_exchange_third_party_invite_request(
+        self, room_id: str, event_dict: Dict
+    ):
         ret = await self.handler.on_exchange_third_party_invite_request(
             room_id, event_dict
         )
         return ret
 
-    async def check_server_matches_acl(self, server_name, room_id):
+    async def check_server_matches_acl(self, server_name: str, room_id: str):
         """Check if the given server is allowed by the server ACLs in the room
 
         Args:
-            server_name (str): name of server, *without any port part*
-            room_id (str): ID of the room to check
+            server_name: name of server, *without any port part*
+            room_id: ID of the room to check
 
         Raises:
             AuthError if the server does not match the ACL
@@ -661,15 +697,15 @@ async def check_server_matches_acl(self, server_name, room_id):
         raise AuthError(code=403, msg="Server is banned from room")
 
 
-def server_matches_acl_event(server_name, acl_event):
+def server_matches_acl_event(server_name: str, acl_event: EventBase) -> bool:
     """Check if the given server is allowed by the ACL event
 
     Args:
-        server_name (str): name of server, without any port part
-        acl_event (EventBase): m.room.server_acl event
+        server_name: name of server, without any port part
+        acl_event: m.room.server_acl event
 
     Returns:
-        bool: True if this server is allowed by the ACLs
+        True if this server is allowed by the ACLs
     """
     logger.debug("Checking %s against acl %s", server_name, acl_event.content)
 
@@ -713,7 +749,7 @@ def server_matches_acl_event(server_name, acl_event):
     return False
 
 
-def _acl_entry_matches(server_name, acl_entry):
+def _acl_entry_matches(server_name: str, acl_entry: str) -> Match:
     if not isinstance(acl_entry, six.string_types):
         logger.warning(
             "Ignoring non-str ACL entry '%s' (is %s)", acl_entry, type(acl_entry)
@@ -732,13 +768,13 @@ def __init__(self):
         self.edu_handlers = {}
         self.query_handlers = {}
 
-    def register_edu_handler(self, edu_type, handler):
+    def register_edu_handler(self, edu_type: str, handler: Callable[[str, dict], None]):
         """Sets the handler callable that will be used to handle an incoming
         federation EDU of the given type.
 
         Args:
-            edu_type (str): The type of the incoming EDU to register handler for
-            handler (Callable[[str, dict]]): A callable invoked on incoming EDU
+            edu_type: The type of the incoming EDU to register handler for
+            handler: A callable invoked on incoming EDU
                 of the given type. The arguments are the origin server name and
                 the EDU contents.
         """
@@ -749,14 +785,16 @@ def register_edu_handler(self, edu_type, handler):
 
         self.edu_handlers[edu_type] = handler
 
-    def register_query_handler(self, query_type, handler):
+    def register_query_handler(
+        self, query_type: str, handler: Callable[[dict], defer.Deferred]
+    ):
         """Sets the handler callable that will be used to handle an incoming
         federation query of the given type.
 
         Args:
-            query_type (str): Category name of the query, which should match
+            query_type: Category name of the query, which should match
                 the string used by make_query.
-            handler (Callable[[dict], Deferred[dict]]): Invoked to handle
+            handler: Invoked to handle
                 incoming queries of this type. The return will be yielded
                 on and the result used as the response to the query request.
         """
@@ -767,10 +805,11 @@ def register_query_handler(self, query_type, handler):
 
         self.query_handlers[query_type] = handler
 
-    async def on_edu(self, edu_type, origin, content):
+    async def on_edu(self, edu_type: str, origin: str, content: dict):
         handler = self.edu_handlers.get(edu_type)
         if not handler:
             logger.warning("No handler registered for EDU type %s", edu_type)
+            return
 
         with start_active_span_from_edu(content, "handle_edu"):
             try:
@@ -780,7 +819,7 @@ async def on_edu(self, edu_type, origin, content):
             except Exception:
                 logger.exception("Failed to handle edu %r", edu_type)
 
-    def on_query(self, query_type, args):
+    def on_query(self, query_type: str, args: dict) -> defer.Deferred:
         handler = self.query_handlers.get(query_type)
         if not handler:
             logger.warning("No handler registered for query type %s", query_type)
@@ -807,7 +846,7 @@ def __init__(self, hs):
 
         super(ReplicationFederationHandlerRegistry, self).__init__()
 
-    async def on_edu(self, edu_type, origin, content):
+    async def on_edu(self, edu_type: str, origin: str, content: dict):
         """Overrides FederationHandlerRegistry
         """
         if not self.config.use_presence and edu_type == "m.presence":
@@ -821,7 +860,7 @@ async def on_edu(self, edu_type, origin, content):
 
         return await self._send_edu(edu_type=edu_type, origin=origin, content=content)
 
-    async def on_query(self, query_type, args):
+    async def on_query(self, query_type: str, args: dict):
         """Overrides FederationHandlerRegistry
         """
         handler = self.query_handlers.get(query_type)
diff --git a/tox.ini b/tox.ini
index a79fc93b57e2..763c8463d9dd 100644
--- a/tox.ini
+++ b/tox.ini
@@ -183,6 +183,7 @@ commands = mypy \
             synapse/events/spamcheck.py \
             synapse/federation/federation_base.py \
             synapse/federation/federation_client.py \
+            synapse/federation/federation_server.py \
             synapse/federation/sender \
             synapse/federation/transport \
             synapse/handlers/auth.py \