diff --git a/.travis.yml b/.travis.yml
index d304c701..4553e325 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -21,6 +21,12 @@ matrix:
       dist: xenial
       sudo: true
       name: "Python 3.7 without Extensions"
+    - env: TOX_ENV=type-checking
+      python: 3.6
+      name: "Python 3.6 Type checks"
+    - env: TOX_ENV=type-checking
+      python: 3.7
+      name: "Python 3.7 Type checks"
     - env: TOX_ENV=lint
       python: 3.6
       name: "Python 3.6 Linter checks"
diff --git a/sanic/__main__.py b/sanic/__main__.py
index 73de3265..11320305 100644
--- a/sanic/__main__.py
+++ b/sanic/__main__.py
@@ -1,5 +1,6 @@
 from argparse import ArgumentParser
 from importlib import import_module
+from typing import Any, Dict, Optional
 
 from sanic.app import Sanic
 from sanic.log import logger
@@ -35,7 +36,10 @@ if __name__ == "__main__":
                 )
             )
         if args.cert is not None or args.key is not None:
-            ssl = {"cert": args.cert, "key": args.key}
+            ssl = {
+                "cert": args.cert,
+                "key": args.key,
+            }  # type: Optional[Dict[str, Any]]
         else:
             ssl = None
 
diff --git a/sanic/app.py b/sanic/app.py
index 92e1a8dd..5cf06c07 100644
--- a/sanic/app.py
+++ b/sanic/app.py
@@ -11,7 +11,7 @@ from inspect import getmodulename, isawaitable, signature, stack
 from socket import socket
 from ssl import Purpose, SSLContext, create_default_context
 from traceback import format_exc
-from typing import Any, Optional, Type, Union
+from typing import Any, Dict, Optional, Type, Union
 from urllib.parse import urlencode, urlunparse
 
 from sanic import reloader_helpers
@@ -768,7 +768,7 @@ class Sanic:
             URLBuildError
         """
         # find the route by the supplied view name
-        kw = {}
+        kw: Dict[str, str] = {}
         # special static files url_for
         if view_name == "static":
             kw.update(name=kwargs.pop("name", "static"))
diff --git a/sanic/asgi.py b/sanic/asgi.py
index 8f7e5770..f9e49005 100644
--- a/sanic/asgi.py
+++ b/sanic/asgi.py
@@ -2,9 +2,23 @@ import asyncio
 import warnings
 
 from inspect import isawaitable
-from typing import Any, Awaitable, Callable, MutableMapping, Union
+from typing import (
+    Any,
+    Awaitable,
+    Callable,
+    Dict,
+    List,
+    MutableMapping,
+    Optional,
+    Tuple,
+    Union,
+)
 from urllib.parse import quote
 
+from requests_async import ASGISession  # type: ignore
+
+import sanic.app  # noqa
+
 from sanic.compat import Header
 from sanic.exceptions import InvalidUsage, ServerError
 from sanic.log import logger
@@ -54,6 +68,8 @@ class MockProtocol:
 
 
 class MockTransport:
+    _protocol: Optional[MockProtocol]
+
     def __init__(
         self, scope: ASGIScope, receive: ASGIReceive, send: ASGISend
     ) -> None:
@@ -68,11 +84,12 @@ class MockTransport:
             self._protocol = MockProtocol(self, self.loop)
         return self._protocol
 
-    def get_extra_info(self, info: str) -> Union[str, bool]:
+    def get_extra_info(self, info: str) -> Union[str, bool, None]:
         if info == "peername":
             return self.scope.get("server")
         elif info == "sslcontext":
             return self.scope.get("scheme") in ["https", "wss"]
+        return None
 
     def get_websocket_connection(self) -> WebSocketConnection:
         try:
@@ -172,6 +189,13 @@ class Lifespan:
 
 
 class ASGIApp:
+    sanic_app: Union[ASGISession, "sanic.app.Sanic"]
+    request: Request
+    transport: MockTransport
+    do_stream: bool
+    lifespan: Lifespan
+    ws: Optional[WebSocketConnection]
+
     def __init__(self) -> None:
         self.ws = None
 
@@ -182,8 +206,8 @@ class ASGIApp:
         instance = cls()
         instance.sanic_app = sanic_app
         instance.transport = MockTransport(scope, receive, send)
-        instance.transport.add_task = sanic_app.loop.create_task
         instance.transport.loop = sanic_app.loop
+        setattr(instance.transport, "add_task", sanic_app.loop.create_task)
 
         headers = Header(
             [
@@ -286,8 +310,8 @@ class ASGIApp:
         """
         Write the response.
         """
-        headers = []
-        cookies = {}
+        headers: List[Tuple[bytes, bytes]] = []
+        cookies: Dict[str, str] = {}
         try:
             cookies = {
                 v.key: v
diff --git a/sanic/blueprint_group.py b/sanic/blueprint_group.py
index 3850cd20..e6e0ebbb 100644
--- a/sanic/blueprint_group.py
+++ b/sanic/blueprint_group.py
@@ -56,7 +56,7 @@ class BlueprintGroup(MutableSequence):
         """
         return self._blueprints[item]
 
-    def __setitem__(self, index: int, item: object) -> None:
+    def __setitem__(self, index, item) -> None:
         """
         Abstract method implemented to turn the `BlueprintGroup` class
         into a list like object to support all the existing behavior.
@@ -69,7 +69,7 @@ class BlueprintGroup(MutableSequence):
         """
         self._blueprints[index] = item
 
-    def __delitem__(self, index: int) -> None:
+    def __delitem__(self, index) -> None:
         """
         Abstract method implemented to turn the `BlueprintGroup` class
         into a list like object to support all the existing behavior.
diff --git a/sanic/compat.py b/sanic/compat.py
index 6ca7e344..f5475695 100644
--- a/sanic/compat.py
+++ b/sanic/compat.py
@@ -1,4 +1,4 @@
-from multidict import CIMultiDict
+from multidict import CIMultiDict  # type: ignore
 
 
 class Header(CIMultiDict):
diff --git a/sanic/headers.py b/sanic/headers.py
index 6c9fa221..142ab27b 100644
--- a/sanic/headers.py
+++ b/sanic/headers.py
@@ -1,10 +1,10 @@
 import re
 
-from typing import Dict, Iterable, Optional, Tuple
+from typing import Dict, Iterable, List, Optional, Tuple, Union
 from urllib.parse import unquote
 
 
-Options = Dict[str, str]  # key=value fields in various headers
+Options = Dict[str, Union[int, str]]  # key=value fields in various headers
 OptionsIterable = Iterable[Tuple[str, str]]  # May contain duplicate keys
 
 _token, _quoted = r"([\w!#$%&'*+\-.^_`|~]+)", r'"([^"]*)"'
@@ -35,7 +35,7 @@ def parse_content_header(value: str) -> Tuple[str, Options]:
     value = _firefox_quote_escape.sub("%22", value)
     pos = value.find(";")
     if pos == -1:
-        options = {}
+        options: Dict[str, Union[int, str]] = {}
     else:
         options = {
             m.group(1).lower(): m.group(2) or m.group(3).replace("%22", '"')
@@ -67,7 +67,7 @@ def parse_forwarded(headers, config) -> Optional[Options]:
         return None
     # Loop over <separator><key>=<value> elements from right to left
     sep = pos = None
-    options = []
+    options: List[Tuple[str, str]] = []
     found = False
     for m in _rparam.finditer(header[::-1]):
         # Start of new element? (on parser skips and non-semicolon right sep)
@@ -101,8 +101,13 @@ def parse_xforwarded(headers, config) -> Optional[Options]:
         try:
             # Combine, split and filter multiple headers' entries
             forwarded_for = headers.getall(config.FORWARDED_FOR_HEADER)
-            proxies = (p.strip() for h in forwarded_for for p in h.split(","))
-            proxies = [p for p in proxies if p]
+            proxies = [
+                p
+                for p in (
+                    p.strip() for h in forwarded_for for p in h.split(",")
+                )
+                if p
+            ]
             addr = proxies[-proxies_count]
         except (KeyError, IndexError):
             pass
@@ -126,7 +131,7 @@ def parse_xforwarded(headers, config) -> Optional[Options]:
 
 def fwd_normalize(fwd: OptionsIterable) -> Options:
     """Normalize and convert values extracted from forwarded headers."""
-    ret = {}
+    ret: Dict[str, Union[int, str]] = {}
     for key, val in fwd:
         if val is not None:
             try:
@@ -164,4 +169,4 @@ def parse_host(host: str) -> Tuple[Optional[str], Optional[int]]:
     if not m:
         return None, None
     host, port = m.groups()
-    return host.lower(), port and int(port)
+    return host.lower(), int(port) if port is not None else None
diff --git a/sanic/request.py b/sanic/request.py
index 734ad0a3..690213a3 100644
--- a/sanic/request.py
+++ b/sanic/request.py
@@ -6,7 +6,7 @@ from collections import defaultdict, namedtuple
 from http.cookies import SimpleCookie
 from urllib.parse import parse_qs, parse_qsl, unquote, urlunparse
 
-from httptools import parse_url
+from httptools import parse_url  # type: ignore
 
 from sanic.exceptions import InvalidUsage
 from sanic.headers import (
@@ -19,9 +19,9 @@ from sanic.log import error_logger, logger
 
 
 try:
-    from ujson import loads as json_loads
+    from ujson import loads as json_loads  # type: ignore
 except ImportError:
-    from json import loads as json_loads
+    from json import loads as json_loads  # type: ignore
 
 DEFAULT_HTTP_CONTENT_TYPE = "application/octet-stream"
 EXPECT_HEADER = "EXPECT"
diff --git a/sanic/response.py b/sanic/response.py
index e339819f..91fb25f4 100644
--- a/sanic/response.py
+++ b/sanic/response.py
@@ -3,7 +3,7 @@ from mimetypes import guess_type
 from os import path
 from urllib.parse import quote_plus
 
-from aiofiles import open as open_async
+from aiofiles import open as open_async  # type: ignore
 
 from sanic.compat import Header
 from sanic.cookies import CookieJar
diff --git a/sanic/server.py b/sanic/server.py
index f18a27d7..fa38e435 100644
--- a/sanic/server.py
+++ b/sanic/server.py
@@ -10,8 +10,8 @@ from signal import signal as signal_func
 from socket import SO_REUSEADDR, SOL_SOCKET, socket
 from time import time
 
-from httptools import HttpRequestParser
-from httptools.parser.errors import HttpParserError
+from httptools import HttpRequestParser  # type: ignore
+from httptools.parser.errors import HttpParserError  # type: ignore
 
 from sanic.compat import Header
 from sanic.exceptions import (
@@ -28,7 +28,7 @@ from sanic.response import HTTPResponse
 
 
 try:
-    import uvloop
+    import uvloop  # type: ignore
 
     if not isinstance(asyncio.get_event_loop_policy(), uvloop.EventLoopPolicy):
         asyncio.set_event_loop_policy(uvloop.EventLoopPolicy())
diff --git a/sanic/static.py b/sanic/static.py
index 104a820b..cc020bc7 100644
--- a/sanic/static.py
+++ b/sanic/static.py
@@ -4,7 +4,7 @@ from re import sub
 from time import gmtime, strftime
 from urllib.parse import unquote
 
-from aiofiles.os import stat
+from aiofiles.os import stat  # type: ignore
 
 from sanic.exceptions import (
     ContentRangeError,
diff --git a/sanic/testing.py b/sanic/testing.py
index 06d75fc1..f4925b7f 100644
--- a/sanic/testing.py
+++ b/sanic/testing.py
@@ -6,9 +6,9 @@ from json import JSONDecodeError
 from socket import socket
 from urllib.parse import unquote, urlsplit
 
-import httpcore
-import requests_async as requests
-import websockets
+import httpcore  # type: ignore
+import requests_async as requests  # type: ignore
+import websockets  # type: ignore
 
 from sanic.asgi import ASGIApp
 from sanic.exceptions import MethodNotSupported
@@ -288,6 +288,14 @@ class SanicASGIAdapter(requests.asgi.ASGIAdapter):  # noqa
             request_complete = True
             return {"type": "http.request", "body": body_bytes}
 
+        request_complete = False
+        response_started = False
+        response_complete = False
+        raw_kwargs = {"content": b""}  # type: typing.Dict[str, typing.Any]
+        template = None
+        context = None
+        return_value = None
+
         async def send(message) -> None:
             nonlocal raw_kwargs, response_started, response_complete, template, context  # noqa
 
@@ -316,14 +324,6 @@ class SanicASGIAdapter(requests.asgi.ASGIAdapter):  # noqa
                 template = message["template"]
                 context = message["context"]
 
-        request_complete = False
-        response_started = False
-        response_complete = False
-        raw_kwargs = {"content": b""}  # type: typing.Dict[str, typing.Any]
-        template = None
-        context = None
-        return_value = None
-
         try:
             return_value = await self.app(scope, receive, send)
         except BaseException as exc:
diff --git a/sanic/views.py b/sanic/views.py
index 3bfe3850..c4574b8d 100644
--- a/sanic/views.py
+++ b/sanic/views.py
@@ -1,3 +1,5 @@
+from typing import Any, Callable, List
+
 from sanic.constants import HTTP_METHODS
 from sanic.exceptions import InvalidUsage
 
@@ -37,7 +39,7 @@ class HTTPMethodView:
     To add any decorator you could set it into decorators variable
     """
 
-    decorators = []
+    decorators: List[Callable[[Callable[..., Any]], Callable[..., Any]]] = []
 
     def dispatch_request(self, request, *args, **kwargs):
         handler = getattr(self, request.method.lower(), None)
diff --git a/sanic/websocket.py b/sanic/websocket.py
index f87188e4..60092836 100644
--- a/sanic/websocket.py
+++ b/sanic/websocket.py
@@ -1,13 +1,27 @@
-from typing import Any, Awaitable, Callable, MutableMapping, Optional, Union
+from typing import (
+    Any,
+    Awaitable,
+    Callable,
+    Dict,
+    MutableMapping,
+    Optional,
+    Union,
+)
 
-from httptools import HttpParserUpgrade
-from websockets import ConnectionClosed  # noqa
-from websockets import InvalidHandshake, WebSocketCommonProtocol, handshake
+from httptools import HttpParserUpgrade  # type: ignore
+from websockets import (  # type: ignore
+    ConnectionClosed,
+    InvalidHandshake,
+    WebSocketCommonProtocol,
+    handshake,
+)
 
 from sanic.exceptions import InvalidUsage
 from sanic.server import HttpProtocol
 
 
+__all__ = ["ConnectionClosed", "WebSocketProtocol", "WebSocketConnection"]
+
 ASIMessage = MutableMapping[str, Any]
 
 
@@ -125,14 +139,12 @@ class WebSocketConnection:
         self._receive = receive
 
     async def send(self, data: Union[str, bytes], *args, **kwargs) -> None:
-        message = {"type": "websocket.send"}
+        message: Dict[str, Union[str, bytes]] = {"type": "websocket.send"}
 
-        try:
-            data.decode()
-        except AttributeError:
-            message.update({"text": str(data)})
-        else:
+        if isinstance(data, bytes):
             message.update({"bytes": data})
+        else:
+            message.update({"text": str(data)})
 
         await self._send(message)
 
@@ -144,6 +156,8 @@ class WebSocketConnection:
         elif message["type"] == "websocket.disconnect":
             pass
 
+        return None
+
     receive = recv
 
     async def accept(self) -> None:
diff --git a/sanic/worker.py b/sanic/worker.py
index ef8b2128..777f12cf 100644
--- a/sanic/worker.py
+++ b/sanic/worker.py
@@ -5,19 +5,19 @@ import signal
 import sys
 import traceback
 
-import gunicorn.workers.base as base
+import gunicorn.workers.base as base  # type: ignore
 
 from sanic.server import HttpProtocol, Signal, serve, trigger_events
 from sanic.websocket import WebSocketProtocol
 
 
 try:
-    import ssl
+    import ssl  # type: ignore
 except ImportError:
-    ssl = None
+    ssl = None  # type: ignore
 
 try:
-    import uvloop
+    import uvloop  # type: ignore
 
     asyncio.set_event_loop_policy(uvloop.EventLoopPolicy())
 except ImportError:
diff --git a/tox.ini b/tox.ini
index f8138edd..9eca7f58 100644
--- a/tox.ini
+++ b/tox.ini
@@ -38,6 +38,13 @@ commands =
     black --config ./.black.toml --check --verbose sanic/
     isort --check-only --recursive sanic
 
+[testenv:type-checking]
+deps =
+    mypy
+
+commands =
+    mypy sanic
+
 [testenv:check]
 deps =
     docutils