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http client/server for asyncio

Project description

http client/server for asyncio

aiohttp logo


  • Supports both client and server side of HTTP protocol.

  • Supports both client and server Web-Sockets out-of-the-box.

  • Web-server has middlewares and pluggable routing.

Getting started


To retrieve something from the web:

import aiohttp
import asyncio

async def fetch(session, url):
    with aiohttp.Timeout(10, loop=session.loop):
        async with session.get(url) as response:
            return await response.text()

async def main(loop):
    async with aiohttp.ClientSession(loop=loop) as session:
        html = await fetch(session, '')

if __name__ == '__main__':
    loop = asyncio.get_event_loop()


This is simple usage example:

from aiohttp import web

async def handle(request):
    name = request.match_info.get('name', "Anonymous")
    text = "Hello, " + name
    return web.Response(text=text)

async def wshandler(request):
    ws = web.WebSocketResponse()
    await ws.prepare(request)

    async for msg in ws:
        if msg.type == web.MsgType.text:
            ws.send_str("Hello, {}".format(
        elif msg.type == web.MsgType.binary:
        elif msg.type == web.MsgType.close:

    return ws

app = web.Application()
app.router.add_get('/echo', wshandler)
app.router.add_get('/', handle)
app.router.add_get('/{name}', handle)


Note: examples are written for Python 3.5+ and utilize PEP-492 aka async/await. If you are using Python 3.4 please replace await with yield from and async def with @coroutine e.g.:

async def coro(...):
    ret = await f()

should be replaced by:

def coro(...):
    ret = yield from f()


Discussion list

aio-libs google group:!forum/aio-libs


Optionally you may install the cChardet and aiodns libraries (highly recommended for sake of speed).


aiohttp is offered under the Apache 2 license.

Source code

The latest developer version is available in a github repository:


If you are interested in by efficiency, AsyncIO community maintains a list of benchmarks on the official wiki:


1.0.2 (2016-09-22)

  • Make CookieJar compatible with 32-bit systems #1188

  • Add missing WSMsgType to web_ws.__all__, see #1200

  • Fix CookieJar ctor when called with loop=None #1203

  • Fix broken upper-casing in wsgi support #1197

1.0.1 (2016-09-16)

  • Restore aiohttp.web.MsgType alias for aiohttp.WSMsgType for sake of backward compatibility #1178

  • Tune alabaster schema.

  • Use text/html content type for displaying index pages by static file handler.

  • Fix AssertionError in static file handling #1177

  • Fix access log formats %O and %b for static file handling

  • Remove debug setting of GunicornWorker, use app.debug to control its debug-mode instead

1.0.0 (2016-09-16)

  • Change default size for client session’s connection pool from unlimited to 20 #977

  • Add IE support for cookie deletion. #994

  • Remove deprecated WebSocketResponse.wait_closed method (BACKWARD INCOMPATIBLE)

  • Remove deprecated force parameter for ClientResponse.close method (BACKWARD INCOMPATIBLE)

  • Avoid using of mutable CIMultiDict kw param in make_mocked_request #997

  • Make WebSocketResponse.close a little bit faster by avoiding new task creating just for timeout measurement

  • Add proxy and proxy_auth params to client.get() and family, deprecate ProxyConnector #998

  • Add support for websocket send_json and receive_json, synchronize server and client API for websockets #984

  • Implement router shourtcuts for most useful HTTP methods, use app.router.add_get(), app.router.add_post() etc. instead of app.router.add_route() #986

  • Support SSL connections for gunicorn worker #1003

  • Move obsolete examples to legacy folder

  • Switch to multidict 2.0 and title-cased strings #1015

  • {FOO}e logger format is case-sensitive now

  • Fix logger report for unix socket 8e8469b

  • Rename aiohttp.websocket to aiohttp._ws_impl

  • Rename aiohttp.MsgType tp aiohttp.WSMsgType

  • Introduce aiohttp.WSMessage officially

  • Rename Message -> WSMessage

  • Remove deprecated decode param from

  • Use 5min default client timeout #1028

  • Relax HTTP method validation in UrlDispatcher #1037

  • Pin minimal supported asyncio version to 3.4.2+ (loop.is_close() should be present)

  • Remove aiohttp.websocket module (BACKWARD INCOMPATIBLE) Please use high-level client and server approaches

  • Link header for 451 status code is mandatory

  • Fix test_client fixture to allow multiple clients per test #1072

  • make_mocked_request now accepts dict as headers #1073

  • Add Python 3.5.2/3.6+ compatibility patch for async generator protocol change #1082

  • Improvement test_client can accept instance object #1083

  • Simplify ServerHttpProtocol implementation #1060

  • Add a flag for optional showing directory index for static file handling #921

  • Define web.Application.on_startup() signal handler #1103

  • Drop ChunkedParser and LinesParser #1111

  • Call Application.startup in GunicornWebWorker #1105

  • Fix client handling hostnames with 63 bytes when a port is given in the url #1044

  • Implement proxy support for ClientSession.ws_connect #1025

  • Return named tuple from WebSocketResponse.can_prepare #1016

  • Fix access_log_format in GunicornWebWorker #1117

  • Setup Content-Type to application/octet-stream by default #1124

  • Deprecate debug parameter from app.make_handler(), use Application(debug=True) instead #1121

  • Remove fragment string in request path #846

  • Use aiodns.DNSResolver.gethostbyname() if available #1136

  • Fix static file sending on uvloop when sendfile is available #1093

  • Make prettier urls if query is empty dict #1143

  • Fix redirects for HEAD requests #1147

  • Default value for StreamReader.read_nowait is -1 from now #1150

  • aiohttp.StreamReader is not inherited from asyncio.StreamReader from now (BACKWARD INCOMPATIBLE) #1150

  • Streams documentation added #1150

  • Add multipart coroutine method for web Request object #1067

  • Publish ClientSession.loop property #1149

  • Fix static file with spaces #1140

  • Fix piling up asyncio loop by cookie expiration callbacks #1061

  • Drop Timeout class for sake of async_timeout external library. aiohttp.Timeout is an alias for async_timeout.timeout

  • use_dns_cache parameter of aiohttp.TCPConnector is True by default (BACKWARD INCOMPATIBLE) #1152

  • aiohttp.TCPConnector uses asynchronous DNS resolver if available by default (BACKWARD INCOMPATIBLE) #1152

  • Conform to RFC3986 - do not include url fragments in client requests #1174

  • Drop ClientSession.cookies (BACKWARD INCOMPATIBLE) #1173

  • Refactor AbstractCookieJar public API (BACKWARD INCOMPATIBLE) #1173

  • Fix clashing cookies with have the same name but belong to different domains (BACKWARD INCOMPATIBLE) #1125

  • Support binary Content-Transfer-Encoding #1169

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