1.1.1 • Public • Published

    WSSiP: A WebSocket Manipulation Proxy

    Travis-CI Appveyor npm version npm github github release dependency outdated

    Short for "WebSocket/ Proxy", this tool, written in Node.js, provides a user interface to capture, intercept, send custom messages and view all WebSocket and Socket.IO communications between the client and server.

    Upstream proxy support also means you can forward HTTP/HTTPS traffic to an intercepting proxy of your choice (e.g. Burp Suite or Pappy Proxy) but view WebSocket traffic in WSSiP. More information can be found on the blog post.

    There is an outward bridge via HTTP to write a fuzzer in any language you choose to debug and fuzz for security vulnerabilities. See Fuzzing for more details.

    Written and maintained by Samantha Chalker (@thekettu). Icon for WSSiP release provided by @dragonfoxing.


    From Packaged Application

    See Releases.

    From npx via npm (for CLI commands)

    Run the following in your command line:

    npx wssip

    From Source

    Using a command line:

    # Clone repository locally 
    git clone
    # Change to the directory 
    cd wssip
    # If you are developing for WSSiP: 
    # npm i 
    # If not... (as to minimize disk space): 
    npm i electron
    npm i --production
    # Yarn version: 
    # yarn add electron 
    # yarn install --production 
    # Start application: 
    npm start
    # or yarn: 
    # yarn start 


    1. Open the WSSiP application.
    2. WSSiP will start listening automatically. This will default to localhost on port 8080.
    3. Optionally, use Tools > Use Upstream Proxy to use another intercepting proxy to view web traffic.
    4. Configure the browser to point to http://localhost:8080/ as the HTTP Proxy.
    5. Navigate to a page using WebSockets. A good example is the WS Echo Demonstration.
    6. ???
    7. Potato.


    WSSiP provides an HTTP bridge via the man-in-the-middle proxy for custom applications to help fuzz a connection. These are accessed over the proxy server.

    A few of the simple CA certificate downloads are:

    Get WebSocket Connection Info

    Returns whether the WebSocket id is connected to a web server, and if so, return information.

    • URL

      GET http://mitm/ws/:id

    • URL Params


    • Success Response (Not Connected)

      • Code: 200
        Content: {connected: false}
    • Success Response (Connected)

      • Code: 200
        Content: {connected: true, url: 'ws://', bytesReceived: 0, extensions: {}, readyState: 3, protocol: '', protocolVersion: 13}

    Send WebSocket Data

    Send WebSocket data.

    • URL

      POST http://mitm/ws/:id/:sender/:mode/:type?log=:log

    • URL Params



      sender one of client or server

      mode one of message, ping or pong

      type one of ascii or binary (text is an alias of ascii)


      log either true or y to log in the WSSiP application. Errors will be logged in the WSSiP application instead of being returned via the REST API.

    • Data Params

      Raw data in the POST field will be sent to the WebSocket server.

    • Success Response:

      • Code: 200
        Content: {success: true}
    • Error Response:

      • Code: 500
        Content: {success: false, reason: 'Error message'}


    Pull requests are welcomed and encouraged. WSSiP supports the debug npm package, and setting the environment variable DEBUG=wssip:* will output debug information to console.

    There are two commands depending on how you want to compile the Webpack bundle: for development, that is npm run compile:dev and for production is npm run compile. React will also log errors depending on whether development or production is specified.

    Currently working on:

    • Exposed API for external scripts for fuzzing (99% complete, it is live but need to test more data)
    • Saving/Resuming Connections from File (35% complete, exporting works sans active connections)
    • Using WSSiP in browser without Electron (likely 1.1.0)
    • Rewrite in TypeScript (likely 1.2.0)
    • Using something other than Appbar for Custom/Intercept tabs, and styling the options to center better

    For information on using the mitmengine class, see: npm, yarn, or mitmengine/


    npm i wssip

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