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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 get_body(client, url):
    async with client.get(url) as response:
        return await

if __name__ == '__main__':
    loop = asyncio.get_event_loop()
    client = aiohttp.ClientSession(loop=loop)
    raw_html = loop.run_until_complete(get_body(client, ''))

If you want to use timeouts for aiohttp client please use standard asyncio approach:

yield from asyncio.wait_for(client.get(url), 10)


This is simple usage example:

import asyncio
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

async def init(loop):
    app = web.Application(loop=loop)
    app.router.add_route('GET', '/echo', wshandler)
    app.router.add_route('GET', '/{name}', handle)

    srv = await loop.create_server(app.make_handler(),
                                        '', 8080)
    print("Server started at")
    return srv

loop = asyncio.get_event_loop()

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:


0.20.0 (12-28-2015)

  • Extend list of web exceptions, add HTTPMisdirectedRequest, HTTPUpgradeRequired, HTTPPreconditionRequired, HTTPTooManyRequests, HTTPRequestHeaderFieldsTooLarge, HTTPVariantAlsoNegotiates, HTTPNotExtended, HTTPNetworkAuthenticationRequired status codes #644

  • Do not remove AUTHORIZATION header by WSGI handler #649

  • Fix broken support for https proxies with authentication #617

  • Get REMOTE_* and SEVER_* http vars from headers when listening on unix socket #654

  • Add HTTP 308 support #663

  • Add Tf format (time to serve request in seconds, %06f format) to access log #669

  • Remove one and a half years long deprecated ClientResponse.read_and_close() method

  • Optimize chunked encoding: use a single syscall instead of 3 calls on sending chunked encoded data

  • Use TCP_CORK and TCP_NODELAY to optimize network latency and throughput #680

  • Weboscket XOR performance improved #687

  • Avoid sending cookie attributes in Cookie header #613

  • Round server timeouts to second for grouping pending call. That leads to less amount of poller syscalls e.g epoll.poll(). #702

  • Close connection on websocket hadshake error #703

  • Implement class based views #684

  • Add headers parameter to ws_connect() #709

  • Drop unused function parse_remote_addr() #708

  • Close session on exception #707

  • Store http code and headers in WSServerHandshakeError #706

  • Make some low-level message properies readonly #710

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