A Haskell library for creating WebSocket-capable servers
Haskell JavaScript HTML CSS Shell




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
  • Fedor Gogolev
  • Nathan Howell
  • Steffen Schuldenzucker
  • Yi Huang
  • Carl Chatfield


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 two kinds of tests: Haskell-based tests (tests/haskell), which use the test-framework library. Additionally, there are integration tests available in tests/javascript, which require a browser to run.