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http-kit is a minimalist and efficient Ring-compatible HTTP client+server for Clojure.

It uses an event-driven architecture to support highly concurrent a/synchronous web applications, and features a simple unified API for WebSocket and HTTP long-polling/streaming.

• 2025-04-15 v2.9.0-beta1: (dev) release info
• 2024-02-30 v2.8.0: (stable) release info

See here for earlier releases.

• Ring compliant: http-kit is a drop-in replacement for the standard Ring Jetty adapter. You can use it with all your current libraries and middleware.

• High performance: http-kit uses an event-driven architecture like nginx, and is fast. See here for benchmarks.

• High concurrency: http-kit is efficient. Its RAM usage is O(n), with only few kB used per connection. Tests have shown http-kit happily serving >600k concurrent connections.

• Clean, simple, small: written from the ground-up to be lean, the entire http-kit client+server JAR is ~90kB with zero dependencies and ~3k total lines of code.

• Sync or async: synchronous is simple, asynchronous fast & flexible. With http-kit you get the best of both with a simple API that lets you mix & match to best fit your use case.

• WebSockets: realtime web apps are a breeze with http-kit, with great out-the-box support for both WebSockets and efficient HTTP long-polling.

For production environments, it's strongly recommended to run http-kit behind a well-configured and battle-hardened reverse proxy like nginx, Caddy, HAProxy, AWS ALB, etc.

See here for more info.

http-kit now includes an extensive single-system benchmark suite that can be easily customized and run in your own environment.

See here for http-kit's benchmark philosophy, usage info, detailed results, etc.

Selected example results:

Important: as with all benchmarks - please be skeptical and check the details for important context!

http-kit was created by @shenfeng, but is currently being maintained by its community.

A big thank-you to the current contributors for keeping the project going! Additional contributors very welcome: please ping me if you'd be interested in lending a hand.

- Peter Taoussanis

• Wiki (getting started, usage, etc.)
• API reference via cljdoc
• Support via Slack channel or GitHub issues

Copyright © 2012-2025 Feng Shen and contributors.
Licensed under Apache 2.0.