A Haskell library for creating WebSocket-capable servers




Provides a sensible, clean and simple way to write WebSocket-capable servers in Haskell.

The following program echoes messages back after appending meow:

{-# LANGUAGE OverloadedStrings #-}
import           Control.Monad      (forever)
import qualified Data.Text          as T
import qualified Network.WebSockets as WS

meow :: WS.Connection -> IO ()
meow conn = forever $ do
    msg <- WS.receiveData conn
    WS.sendTextData conn $ msg `T.append` ", meow"

Installation is provided using cabal:

$ cabal install websockets


An initial WebSockets library was written in 2010 by Siniša Biđin. In 2011, it was rewritten from scratch, and extended to its current state by Jasper Van der Jeugt, who is also the current maintainer.


  • Alex Lang
  • Carl Chatfield
  • Fedor Gogolev
  • Marcin Tolysz
  • Nathan Howell
  • Steffen Schuldenzucker
  • Yi Huang


Pull requests are always welcome!

This library is production-quality. Therefore we have very high standards in terms of code style, API quality and testing.

We have three kinds of tests:

  • Haskell-based tests (tests/haskell), which use the test-framework library
  • Integration tests, available in tests/javascript. These require a browser to run.
  • We also run the extensive autobahn testsuite.