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Async HTTP with aiohttp

Asyncio Core

aiohttp Recipes

aiohttp brings fast async HTTP clients and servers to your toolbox. Here’s how to get productive quickly.

Build a clientServe requests

Client example​

import aiohttp
import asyncio

async def fetch(session, url):
    async with session.get(url, timeout=10) as resp:
        resp.raise_for_status()
        return await resp.json()

async def main():
    async with aiohttp.ClientSession() as session:
        data = await asyncio.gather(*(fetch(session, url) for url in urls))

asyncio.run(main())
  • Reuse ClientSession for connection pooling.
  • Use timeouts and raise_for_status() to handle failures.

Server example​

from aiohttp import web

async def handle(request):
    return web.json_response({'status': 'ok'})

app = web.Application()
app.router.add_get('/health', handle)
web.run_app(app)
  • Middleware and signals mirror familiar patterns from Flask/FastAPI.
  • Combine with async DB drivers (asyncpg) for full-stack async.

Next up in your learning path

async/await essentials

Ensure you’re comfortable writing coroutines.

Prerequisite

Async test strategies

Use pytest-asyncio patterns covered in the async/await guide.

Quality

Event loop mastery

Deepen how the loop schedules tasks and handles backpressure.

Deep dive