slowapi

A rate limiting extension for Starlette and Fastapi

slowapi Permissive license MIT Active ★ 2,045 v0.1.10 released 2026-06-13

Install

slowapi on PyPI

pip

pip install slowapi

uv

uv add slowapi

poetry

poetry add slowapi

Package facts

License	MIT (permissive)
Python support	supports the current Python release (<4.0,>=3.7)
Install friction	low — pure-Python wheel
Runtime dependencies	1 — limits
Maintenance	actively maintained — 61 days since the last release
Last repo commit	2026-08-04
First released	2020-02-21
Popularity	one of the top 1,000 most-downloaded packages on PyPI (30-day window, as of 2026-08-13)
Known vulnerabilities	none known (OSV.dev, checked 2026-08-13)

Evidence: slowapi-0.1.10-py3-none-any.whl

License :: OSI Approved :: MIT LicenseProgramming Language :: Python :: 3Programming Language :: Python :: 3.10Programming Language :: Python :: 3.11Programming Language :: Python :: 3.12Programming Language :: Python :: 3.13Programming Language :: Python :: 3.7Programming Language :: Python :: 3.8Programming Language :: Python :: 3.9

About slowapi

from the package's own PyPI description — quoted content, verbatim

SlowApi

A rate limiting library for Starlette and FastAPI adapted from flask-limiter.

This package is used in various production setups, handling millions of requests per month, and seems to behave as expected. There might be some API changes when changing the code to be fully async, but we will notify users via appropriate semver version changes.

The documentation is on read the docs.

Quick start

Installation

slowapi is available from pypi so you can install it as usual:

$ pip install slowapi

Features

Most feature are coming from FlaskLimiter and the underlying limits.

Supported now:

Single and multiple limit decorator on endpoint functions to apply limits
redis, memcached and memory backends to track your limits (memory as a fallback)
support for sync and async HTTP endpoints
Support for shared limits across a set of routes
The library aims to support all currently supported versions of python

Limitations and known issues

The...

Read as markdown · JSON record · Source repository · Homepage · Docs

AI interpretation — verify before relying

AI-generated interpretation of the package facts above; every digit, version, license, or vulnerability id it cites is grounded in the facts already shown on this page

SlowApi provides rate limiting for Starlette and FastAPI applications, wrapping the limits library to enforce request quotas on endpoints using decorators and configurable backends.

Low friction: pure Python wheel with a single runtime dependency (limits). Actively maintained with recent release 61 days ago and 2045 GitHub stars. Supports Python 3.7–3.13.

MIT license permits commercial and private use with minimal restrictions—suitable for most projects requiring only attribution.

Usage

pip install slowapi

from slowapi import Limiter
from slowapi.util import get_remote_address
from limits import storage

limiter = Limiter(key_func=get_remote_address)

@limiter.limit("5/minute")
async def endpoint(request):
    return {"message": "success"}

The request parameter must be explicitly declared in the endpoint signature for rate limiting to work; websocket endpoints are not supported.

Verdict: SlowApi is a well-maintained, production-ready rate limiter with low install friction, permissive MIT licensing, and no known vulnerabilities. The single dependency (limits) and active maintenance make it a solid choice for adding request throttling to async web applications.

Needs verification

Whether the in-memory backend is suitable for multi-process deployments or if Redis/Memcached is required for scaling.
Performance characteristics and latency overhead of rate-limit checks under high request volumes.
Current API stability status regarding promised async-related semver changes.

rate limiting fastapirequest throttling starletteapi rate limiter decoratorendpoint quota limitingredis rate limitingasync rate limiterrequest throttle