Cowboy

Judgement

What it is

Building block

What it does

A small, fast HTTP server for Erlang/OTP supporting HTTP/1.1, HTTP/2, WebSockets and REST handlers, used underneath Phoenix.

Adopt it when

You build services on the Erlang VM and need the HTTP server layer.

Watch out

Low-level, so most Elixir teams use it through Phoenix or Plug rather than directly.

Ready for

Production-ready

Runs as

Library

Built with

Erlang

How established

Established: started 15 years ago, no tagged release yet.

What the license allows

You can build it into a product you sell, as long as you keep its copyright notice.

Judged on 2026-11-03 from the project's README and GitHub data. The license and age lines are worked out directly.

Built from

Follow it down: Cowboy → OTP → GCC → LLVM project → runs on a microchip

How compilers were built, back to punched paper tape

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