What is the WebSocket protocol?

WebSocket is a standardized internet protocol (RFC 6455) that provides full-duplex, persistent communication channels over a single TCP connection. Unlike HTTP, which follows a request–response model where the client must initiate every exchange, WebSocket allows both the client and the server to send messages at any time after the connection is established. The connection begins as an HTTP upgrade request and then switches to the WebSocket framing protocol, keeping the socket open until either side explicitly closes it.

WebSocket is widely used in applications that require low-latency, real-time updates: chat applications, live dashboards, multiplayer games, collaborative editors, and financial data feeds.

Tool description

This tool provides an interactive WebSocket client that runs entirely in the browser. Connect to any WebSocket server using a ws:// or wss:// URL, compose text or JSON messages, send them, and watch the server's responses appear in a timestamped log. It is useful for testing server behavior, debugging message formats, and exploring WebSocket APIs without writing any code.

Features

  • Text and JSON modes — write messages as plain text or switch to JSON mode with syntax highlighting and payload validation before sending.
  • Timestamped message log — every received message, connection event, and error is recorded with the time it occurred, making it easy to trace the sequence of events.
  • Preset and custom servers — quickly connect to a built-in echo server for immediate testing, or enter any custom WebSocket URL and save it for reuse.

Options explained

Server URL — a ws:// (unencrypted) or wss:// (TLS-encrypted) WebSocket URL, e.g., wss://echo.example.com/ws. The URL must point to an endpoint that speaks the WebSocket protocol.

Ready state — displayed in the output area and reflects the current connection state: CONNECTING (handshake in progress), OPEN (connected and ready), CLOSING (close handshake in progress), or CLOSED (connection terminated).

Data type — switch between Text and JSON composition modes. In JSON mode the editor validates the payload and shows a syntax error if the JSON is malformed.

Auto-scroll — when enabled, the message log scrolls automatically to the most recent entry.

How it works

The tool opens a native browser WebSocket object pointed at the target URL. After the HTTP upgrade handshake completes, the connection enters the OPEN state and messages can flow in both directions. All message events from the server are captured and appended to the log. Clicking Disconnect triggers a clean close handshake.

Tips

  • Use the built-in wss://echo.rapidtoolset.com/ws preset to verify your browser can establish a WebSocket connection at all. The echo server returns every message you send.
  • If the connection stays in CONNECTING indefinitely, a firewall or proxy may be blocking the WebSocket upgrade request.
  • wss:// (WebSocket over TLS) is required on HTTPS pages due to browser mixed-content restrictions; plain ws:// connections will be blocked.
  • For testing Socket.IO servers use the Socket.IO Test Client, and for SockJS servers use the SockJS Test Client — both use different subprotocols incompatible with this tool.