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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):
        async with session.get(url) as response:
            return await response.text()

if __name__ == '__main__':
    loop = asyncio.get_event_loop()
    with aiohttp.ClientSession(loop=loop) as session:
        html = loop.run_until_complete(
            fetch(session, ''))


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(body=text.encode('utf-8'))

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

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

    return ws

app = web.Application()
app.router.add_route('GET', '/echo', wshandler)
app.router.add_route('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()

shoud be replaced by:

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


Discussion list

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


Optionally you may install cChardet library:


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:


0.22.3 (07-26-2016)

  • Do not filter cookies if unsafe flag provided #1005

0.22.2 (07-23-2016)

  • Suppress CancelledError when Timeout raises TimeoutError #970

  • Don’t expose aiohttp.__version__

  • Add unsafe parameter to CookieJar #968

  • Use unsafe cookie jar in test client tools

  • Expose aiohttp.CookieJar name

0.22.1 (07-16-2016)

  • Large cookie expiration/max-age doesn’t break an event loop from now (fixes #967)

0.22.0 (07-15-2016)

  • Fix bug in serving static directory #803

  • Fix command line arg parsing #797

  • Fix a documentation chapter about cookie usage #790

  • Handle empty body with gzipped encoding #758

  • Support 451 Unavailable For Legal Reasons http status #697

  • Fix Cookie share example and few small typos in docs #817

  • UrlDispatcher.add_route with partial coroutine handler #814

  • Optional support for aiodns #728

  • Add ServiceRestart and TryAgainLater websocket close codes #828

  • Fix prompt message for web.run_app #832

  • Allow to pass None as a timeout value to disable timeout logic #834

  • Fix leak of connection slot during connection erro #835

  • Gunicorn worker with uvloop support aiohttp.worker.GunicornUVLoopWebWorker #878

  • Don’t send body in response to HEAD request #838

  • Skip the preamble in MultipartReader #881

  • Implement BasicAuth decode classmethod. #744

  • Don’t crash logger when transport is None #889

  • Use a create_future compatibility wrapper instead of creating Futures directly #896

  • Add test utilities to aiohttp #902

  • Improve Request.__repr__ #875

  • Skip DNS resolving if provided host is already an ip address #874

  • Add headers to ClientSession.ws_connect #785

  • Document that server can send pre-compressed data #906

  • Don’t add Content-Encoding and Transfer-Encoding if no body #891

  • Add json() convenience methods to websocket message objects #897

  • Add client_resp.raise_for_status() #908

  • Implement cookie filter #799

  • Include an example of middleware to handle error pages #909

  • Fix error handling in StaticFileMixin #856

  • Add mocked request helper #900

  • Fix empty ALLOW Response header for cls based View #929

  • Respect CONNECT method to implement a proxy server #847

  • Add pytest_plugin #914

  • Add tutorial

  • Add backlog option to support more than 128 (default value in “create_server” function) concurrent connections #892

  • Allow configuration of header size limits #912

  • Separate sending file logic from StaticRoute dispatcher #901

  • Drop deprecated share_cookies connector option (BACKWARD INCOMPATIBLE)

  • Drop deprecated support for tuple as auth paramter. Use aiohttp.BasicAuth instead (BACKWARD INCOMPATIBLE)

  • Remove deprecated request.payload property, use content instead. (BACKWARD INCOMPATIBLE)

  • Drop all mentions about api changes in documentaion for versions older than 0.16

  • Allow to override default cookie jar #963

  • Add manylinux wheel builds

  • Dup a socket for sendfile usage #964

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