---
id: aiolimiter
version: "1.2.1"
license: MIT
license_treatment: permissive
maintenance: active
---

# aiolimiter — asyncio rate limiter, a leaky bucket implementation

License: permissive · Maintenance: active · Downloads: 12.5M/mo

## What it is and what it does

aiolimiter provides a rate limiter for asyncio applications using the leaky bucket algorithm. It lets you specify a maximum number of concurrent entries into a code section within a given time window, which is useful for controlling how fast async operations execute—for example, limiting API calls, database queries, or other I/O-bound tasks.

The package is a pure Python implementation with no external runtime dependencies, making it lightweight and easy to integrate. It's designed for developers building asyncio applications who need fine-grained control over concurrency and throughput without adding complexity or external service dependencies.

Use it for:

- Limit concurrent API requests to a third-party service to avoid hitting rate limits or overwhelming the server.
- Control database query concurrency to prevent connection pool exhaustion in async applications.
- Throttle background task execution to spread load evenly across a time window.
- Prevent resource exhaustion by capping how many async operations can run simultaneously.
- Implement fair-share scheduling for multiple concurrent coroutines competing for a shared resource.

## Worth the install?

AI-flagged interpretation of the facts above — verify before relying.

Implements a rate limiter for asyncio using the leaky bucket algorithm, allowing you to control how often a code section executes within a time window.

Yes. aiolimiter is a lightweight, actively maintained rate-limiting tool with no dependencies, permissive licensing, and broad Python version support. It solves a common problem in asyncio applications with a proven algorithm and straightforward API. Install it if you need to control concurrency or throughput in async code.

## Install

pip install aiolimiter
uv add aiolimiter
poetry add aiolimiter

## Installing aiolimiter

Before you install: Low install friction with no runtime dependencies. Actively maintained with recent commits and broad Python version support from 3.8 through 3.13.

License in practice: MIT license is permissive; you can use this package freely in commercial and open-source projects with minimal restrictions.

Quickstart:

pip install aiolimiter

from aiolimiter import AsyncLimiter

rate_limit = AsyncLimiter(100, 30)

async def some_coroutine():
    async with rate_limit:
        await do_something()

Requires Python 3.8 or newer.

## Package facts

- License: MIT (permissive)
- Python support: supports_current
- Install friction: low
- Maintenance: active
- Downloads: 12.5M/month (top 5,000 on PyPI)
- Known vulnerabilities: none known

## Tags

asyncio rate limiting, leaky bucket algorithm, async concurrency control, rate limiter for coroutines, asyncio throttling, concurrent request limiting, asyncio, concurrency-control, rate-limiting

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