WebSocket Tester - Free Online Tool | PivaBox

Test WebSocket connections — connect to any endpoint, send and receive messages in real-time

WebSocket Tester — Connect to WebSocket Endpoints, Send and Receive Real-Time Messages, and Debug Bidirectional Communication with Preset Echo Servers

1. Enter a WebSocket URL — use wss:// for secure WebSocket connections (WebSocket over TLS, the standard for production) or ws:// for unencrypted connections (development/localhost only). Choose from preset endpoints for quick testing: the Echo Test preset (wss://ws.postman-echo.com/raw) echoes back any message you send — perfect for verifying connectivity and message round-trip; the Public Echo preset (wss://echo.websocket.org) provides an alternative public echo service. WebSocket is the foundational protocol for real-time web applications — chat systems, live dashboards, collaborative editing, gaming, financial tickers, and any application requiring server-to-client push without polling.
2. Click Connect to establish the WebSocket connection. The connection status indicator shows the current state: Connecting (the WebSocket handshake is in progress — the browser sends an HTTP Upgrade request, and the server responds with HTTP 101 Switching Protocols), Connected (the bidirectional message channel is open — you can send and receive messages), or Disconnected (the connection is closed, with the close code and reason displayed). The connection timer tracks how long the current session has been active — useful for monitoring connection stability and detecting unexpected disconnections.
3. Type your message in the input field and click Send or press Enter. The message log displays all communication in a color-coded timeline: green for sent messages, blue for received messages, gray for system events (connection opened, connection closed with code), and red for errors. Each log entry shows the timestamp, direction, and full message content — click any entry to inspect the raw data. Use the Clear Log button to reset the display for a new testing session. The WebSocket Tester is ideal for: debugging WebSocket API implementations, testing real-time features during development, verifying server upgrade handshake behavior, and learning the WebSocket protocol interactively. All communication is direct between your browser and the WebSocket server — no intermediary proxy or logging service.

Frequently Asked Questions

How does WebSocket differ from HTTP, and when should I use WebSocket vs Server-Sent Events (SSE) or HTTP polling?

WebSocket, HTTP, and SSE each serve different communication patterns. <strong>HTTP (request-response)</strong>: client sends a request, server sends a response, connection closes. Best for: REST APIs, static resource loading, form submissions — any request-initiated interaction. <strong>HTTP Long Polling</strong>: client sends request, server holds it open until data is available or timeout. Simpler than WebSocket but wastes resources holding open connections and re-establishing them after each response. <strong>Server-Sent Events (SSE)</strong>: server-to-client unidirectional stream over HTTP. Simpler than WebSocket, auto-reconnects natively, works through most proxies. Best for: live feeds, notifications, status updates where the client only receives data. <strong>WebSocket</strong>: full-duplex bidirectional communication over a persistent TCP connection. Lowest latency, least overhead (no HTTP headers per message after the initial handshake), supports binary and text frames. Best for: chat, collaborative editing, real-time games, financial tickers, any app requiring frequent two-way communication. WebSocket requires a dedicated server implementation and may have issues with corporate firewalls that don't support the Upgrade header. The PivaBox WebSocket Tester helps you experiment with WebSocket connections directly in your browser.

What's the WebSocket handshake process, and what do the connection codes mean when a WebSocket disconnects?

The WebSocket connection lifecycle: (1) <strong>Handshake</strong> — the client sends an HTTP GET request with <code>Upgrade: websocket</code> and <code>Connection: Upgrade</code> headers, plus a <code>Sec-WebSocket-Key</code> (a random Base64 value). The server validates this and responds with HTTP <code>101 Switching Protocols</code>, a <code>Sec-WebSocket-Accept</code> header (SHA-1 hash of the client key + a fixed GUID), and the connection upgrades from HTTP to the WebSocket protocol. (2) <strong>Data transfer</strong> — after the handshake, data flows as WebSocket frames (not HTTP messages). Frames can be text (UTF-8) or binary (Blob/ArrayBuffer). (3) <strong>Closure</strong> — either side can initiate close with a status code. Common close codes: <code>1000</code> Normal Closure (intentional, clean disconnect), <code>1001</code> Going Away (server shutting down or page navigating away), <code>1006</code> Abnormal Closure (connection lost without close frame — network issue, server crash), <code>1008</code> Policy Violation (endpoint rejected due to policy), <code>1011</code> Internal Server Error. The WebSocket Tester displays close codes and reasons to help diagnose connection issues.

What are the browser security restrictions on WebSocket connections, and how does wss:// protect data?

WebSocket connections are subject to browser security policies: (1) <strong>Same-Origin Policy does NOT apply</strong> — unlike XMLHttpRequest and Fetch, WebSocket connections can connect to any origin; the server decides whether to accept the connection by checking the <code>Origin</code> header in the handshake request. (2) <strong>Mixed content blocking</strong> — <code>ws://</code> connections from <code>https://</code> pages are blocked by most modern browsers (insecure WebSocket on secure page); always use <code>wss://</code> from HTTPS origins. (3) <strong>TLS encryption (wss://)</strong> — WebSocket Secure uses the same TLS encryption as HTTPS; all data after the initial handshake is encrypted end-to-end. The handshake itself contains the <code>Origin</code> header (visible unencrypted in the HTTP Upgrade request) but all subsequent message frames are encrypted. (4) <strong>Authentication</strong> — WebSocket does not have a built-in authentication mechanism; common patterns include: sending a token as a query parameter in the connection URL (<code>wss://api.example.com/ws?token=xxx</code>), sending credentials in the first message after connection, or using cookies (same-origin WebSocket connections automatically include cookies from the handshake). (5) <strong>Rate limiting</strong> — browsers limit the number of concurrent WebSocket connections per origin (typically 6–255 depending on browser). The PivaBox WebSocket Tester operates entirely from your browser — no data passes through our servers.