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Websocket Server


A minimal Websockets Server in Python with no external dependencies.

Notice that this implementation does not support the more advanced features like SSL etc. The project is focused mainly on making it easy to run a websocket server for prototyping, testing or for making a GUI for your application.


You can use the project in three ways.

  1. Copy/paste the file in your project and use it directly
  2. pip install git+ (latest code)
  3. pip install websocket-server (might not be up-to-date)

For coding details have a look at the example and the API.


You can get a feel of how to use the websocket server by running


Then just open client.html in your browser and you should be able to send and receive messages.


Run all tests



The API is simply methods and properties of the WebsocketServer class.


The WebsocketServer can be initialized with the below parameters.

port - The port clients will need to connect to.

host - By default the is used which allows connections only from the current machine. If you wish to allow all network machines to connect, you need to pass as hostname.

loglevel - logging level to print. By default WARNING is used. You can use logging.DEBUG or logging.INFO for more verbose output.


Property Description
clients A list of client


Method Description Takes Gives
set_fn_new_client() Sets a callback function that will be called for every new client connecting to us function None
set_fn_client_left() Sets a callback function that will be called for every client disconnecting from us function None
set_fn_message_received() Sets a callback function that will be called when a client sends a message function None
send_message() Sends a message to a specific client. The message is a simple string. client, message None
send_message_to_all() Sends a message to all connected clients. The message is a simple string. message None

Callback functions

Set by Description Parameters
set_fn_new_client() Called for every new client connecting to us client, server
set_fn_client_left() Called for every client disconnecting from us client, server
set_fn_message_received() Called when a client sends a message client, server, message

The client passed to the callback is the client that left, sent the message, etc. The server might not have any use to use. However it is passed in case you want to send messages to clients.


import logging
from websocket_server import WebsocketServer

def new_client(client, server):
    server.send_message_to_all("Hey all, a new client has joined us")

server = WebsocketServer(13254, host='', loglevel=logging.INFO)


Client is just a dictionary passed along methods.

    'id'      : client_id,
    'handler' : client_handler,
    'address' : (addr, port)