ninenines/cowboy

Small, fast, modern HTTP server for Erlang/OTP.

7,527

stars

1,853

commits

Erlang

primary language

Sep 8, 2026

updated

ninenines.eu

cowboy

erlang

functional

high-performance

http

http2

http2-server

http3

http3-server

https

http-server

production-ready

rest

web

web-framework

websocket

websockets

websocket-server

webtransport

Browse cluster: HTTP/2 and WebSocket Server Implementations →

README

Cowboy is a small, fast and modern HTTP server for Erlang/OTP.

Goals

Cowboy aims to provide a complete HTTP stack in a small code base. It is optimized for low latency and low memory usage, in part because it uses binary strings.

Cowboy provides routing capabilities, selectively dispatching requests to handlers written in Erlang.

Because it uses Ranch for managing connections, Cowboy can easily be embedded in any other application.

Cowboy is clean and well tested Erlang code.

Online documentation

Offline documentation

While still online, run make docs
User guide available in doc/ in PDF and HTML formats
Function reference man pages available in doc/man3/ and doc/man7/
Run make install-docs to install man pages on your system
Full documentation in Asciidoc available in doc/src/
Examples available in examples/

Getting help

Contributors

(top 30 of 119)

1,633 commits

17 commits

17 commits

13 commits

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ninenines/cowboy

Small, fast, modern HTTP server for Erlang/OTP.

7,527

stars

1,853

commits

Erlang

primary language

Sep 8, 2026

updated

ninenines.eu

cowboy

erlang

functional

high-performance

http

http2

http2-server

http3

http3-server

https

http-server

production-ready

rest

web

web-framework

websocket

websockets

websocket-server

webtransport

Browse cluster: HTTP/2 and WebSocket Server Implementations →

README

Cowboy is a small, fast and modern HTTP server for Erlang/OTP.

Goals

Cowboy aims to provide a complete HTTP stack in a small code base. It is optimized for low latency and low memory usage, in part because it uses binary strings.

Cowboy provides routing capabilities, selectively dispatching requests to handlers written in Erlang.

Because it uses Ranch for managing connections, Cowboy can easily be embedded in any other application.

Cowboy is clean and well tested Erlang code.