Middleware¶

Middleware lets you intercept and modify every request and response through FastHTTP — without changing handler code.

What middleware can do¶

Automatically add authorization headers
Log all requests and responses
Add timing and tracing headers
Transform response data
Track errors and metrics

How it works¶

request  →  mw1.request → mw2.request → mw3.request → [HTTP]
response ←  mw1.response ← mw2.response ← mw3.response ← [HTTP]

Middleware executes in __priority__ order on the way in and in reverse order on the way out.

Quick example¶

from fasthttp import FastHTTP
from fasthttp.middleware import BaseMiddleware
from fasthttp.response import Response


class LoggingMiddleware(BaseMiddleware):
    __return_type__ = None
    __priority__ = 0
    __methods__ = None
    __enabled__ = True

    async def request(self, method, url, kwargs):
        print(f"→ {method} {url}")
        return kwargs

    async def response(self, response):
        print(f"← {response.status}")
        return response


app = FastHTTP(middleware=[LoggingMiddleware()])

Output:

→ GET https://httpbin.org/get
← 200

Next steps¶

Creating Middleware — BaseMiddleware API, class attributes, pipe chaining
Examples — auth, logging, timing, method filtering, toggle

Comparison with dependencies¶

Feature	Middleware	Dependencies
Global application	Yes	No
Specific request	No	Yes
Can modify response	Yes	No
Error handling	Yes	No