WebSocket Tester

A free online client to test and debug WebSocket connections. Connect to any WS or WSS server, send and receive messages in real-time, configure heartbeats, and filter logs.

A WebSocket tester connects to WebSocket servers and sends/receives messages in real time. It's essential for debugging WebSocket-based applications like chat systems, live dashboards, and multiplayer games. You can send text or binary messages, view message history, and monitor connection status. This tool uses the browser's native WebSocket API -- connections are made directly from your browser.

Test and debug WebSocket connections without installing anything

Connect to any WSS or WS endpoint, send messages, configure heartbeats, and filter logs. All in your browser — no sign-up, no install.

Real-time debugging

Heartbeat support

Free unlimited

How to use

1
Enter Server URL
Type the full address of your WebSocket server into the input field (e.g., `wss://echo.websocket.events`).
2
Establish Connection
Click "Connect". The status indicator will show "Connecting" and turn green ("Connected") on a successful link.
3
Send Messages
In the "Send Message" box, enter any text or JSON payload and click "Send". Your message will appear in the log.
4
Monitor Responses
Watch the "Message Log" for incoming data from the server, which will be marked as `[RECV]`.
5
Disconnect
Once your testing is complete, click "Disconnect" to close the connection cleanly.

Key Features for Developers

Real-Time Message Log

Instantly see sent and received messages with clear timestamps. Filter by keywords or hide heartbeats to focus on what matters.

Configurable Heartbeat

Keep your connection alive by sending periodic pings. Customize the interval, payload, and the expected server response.

WSS & WS Support

Seamlessly connect to both secure (`wss://`) and insecure (`ws://`) endpoints with helpful mixed-content warnings.

JSON-Friendly

Send any text or JSON payload. The tool does not validate your format, giving you full control over the message structure.

Understanding WebSocket Testing

What are WebSockets and why test them?

WebSocket is a communication protocol (RFC 6455) that provides full-duplex, bidirectional communication over a single TCP connection. Unlike HTTP, which is request-response (the client requests, the server responds, the connection closes), WebSocket keeps the connection open, allowing the server to push data to the client at any time. This makes WebSocket ideal for real-time applications: chat rooms, live sports updates, collaborative editing, multiplayer games, financial trading dashboards, and IoT device monitoring.

WebSocket connections start with an HTTP handshake -- the client sends an HTTP request with an Upgrade: websocket header, and the server responds with 101 Switching Protocols. After the handshake, the connection switches from HTTP to the WebSocket protocol, and both sides can send messages at any time. Messages can be text (UTF-8 strings, often JSON) or binary (ArrayBuffer/Blob). The WebSocket API in browsers is simple: new WebSocket(url) creates a connection, ws.send(data) sends a message, and ws.onmessage handles incoming messages.

Testing WebSocket connections is essential during development because WebSocket bugs are often timing-related -- messages arrive in the wrong order, connections drop unexpectedly, or reconnection logic fails. A WebSocket tester lets you manually send messages to verify the server's response, test edge cases (empty messages, very large messages, rapid-fire messages), and monitor the server's behavior. Without a tester, you'd need to write custom client code for each test scenario, which is time-consuming and error-prone.

Common WebSocket testing scenarios

When testing a WebSocket server, start by verifying the connection: does the server accept the connection at the specified URL? Does it require authentication (via headers, query parameters, or a protocol subprotocol)? Test the handshake by checking if the onopen callback fires. Next, test message exchange: send a simple text message and verify the server responds correctly. Test JSON messages by sending a structured payload and checking the response format. Test binary messages by sending an ArrayBuffer and verifying the server handles binary data.

Test error handling by sending malformed messages (incomplete JSON, oversized payloads, invalid UTF-8). Monitor how the server handles connection drops -- close the connection abruptly and see if the server cleans up resources. Test reconnection by closing and reopening the connection. For performance testing, send messages at high frequency (100+ per second) and monitor latency. For load testing, open multiple concurrent connections and check if the server handles them all. Our tool supports all these scenarios with a clean interface for sending messages and viewing the full message history.

Why Test Your WebSocket Connections?

A reliable WebSocket connection is critical for real-time applications. Using a dedicated tester helps you:

Debug Communication Issues

Quickly identify if the server is receiving messages correctly and inspect the exact data it sends back.

Verify Handshake & Connection

Ensure your server's WebSocket endpoint is live, accessible, and correctly configured for WSS/WS protocols.

Test Heartbeat Logic

Confirm that your server responds correctly to client pings to keep the connection alive through firewalls and proxies.

Prototype Client Behavior

Simulate messages from a client to test how your backend processes different data formats and commands before writing frontend code.

How does this compare to other WebSocket testers?

A side-by-side comparison of popular WebSocket testing tools.

Feature	NovaTools	Postman	PieSocket Tester
Free unlimited		Paid feature
No registration		Required
Text + Binary messages	Both		Text only
Message history	Full log
Custom headers	Subprotocols
Works offline		Cloud sync

Our WebSocket tester runs entirely in your browser using the native WebSocket API. No installation or registration required -- just enter the WebSocket URL and start testing.

FAQ

What is a WebSocket?

WebSocket is a communication protocol providing full-duplex communication channels over a single TCP connection. Unlike HTTP, which follows a request-response model where the client must initiate every interaction, WebSocket allows the server to push data to the client in real-time without being asked. This makes it ideal for live chat applications, multiplayer games, real-time dashboards, collaborative editing, stock tickers, and push notifications. WebSocket connections are persistent — once established, they remain open until either the client or server closes them, eliminating the overhead of repeated HTTP handshakes. The protocol is standardized as RFC 6455 and is supported by all modern browsers, web servers, and reverse proxies.

Why can't I connect to a 'ws://' URL?

Modern browsers enforce 'mixed content blocking', preventing secure HTTPS pages from connecting to insecure WS URLs. This is a security feature designed to prevent man-in-the-middle attacks where an attacker could intercept or modify the WebSocket traffic on an unencrypted connection. To test an insecure `ws://` server, you must load this page via `http://` instead of `https://`. Alternatively, configure your WebSocket server to use secure WebSocket (`wss://`) with a valid TLS certificate. Many cloud platforms (Heroku, Render, Railway) automatically provide TLS certificates, making it easy to upgrade from `ws://` to `wss://`. If you are testing locally, consider using a self-signed certificate with a tool like mkcert.

What is a heartbeat?

A heartbeat is a periodic message sent between the client and server to check if the connection is still alive and to prevent timeouts by firewalls, load balancers, or proxies that may close idle connections. Without heartbeats, a WebSocket connection that has no data flowing through it for 30-60 seconds may be silently dropped by network infrastructure, leaving both client and server unaware that the connection is broken. Our tool allows you to configure automated heartbeat pings — you specify the interval (e.g., every 30 seconds), the payload (e.g., `{"type":"ping"}`), and optionally the expected server response (e.g., `{"type":"pong"}`). The tool sends the ping at the specified interval and logs the server's response, making it easy to verify that the connection is healthy.

How do I send JSON messages?

Simply type your JSON payload into the message input field and click 'Send'. The tool sends the text as-is — most WebSocket servers accept both plain text and JSON. For structured communication, wrap your data in a JSON object with a `type` field that the server can use to route the message: `{"type":"chat","message":"hello","userId":123}`. The tool does not validate your JSON before sending, so you can also send plain text, binary data (as base64), or any other format the server expects. The message log displays both sent and received messages with timestamps, so you can see the full conversation flow.

Can I filter the message log?

Yes. The tool provides a keyword filter that lets you search for specific text in the message log. Type a keyword into the filter box and only messages containing that keyword will be displayed. This is useful for long-running connections with high message volume — for example, filtering for 'error' to see only error messages, or filtering for a specific user ID to track their messages. The tool also provides a toggle to hide heartbeat messages (pings and pongs), which can clutter the log in long sessions. The filter is applied in real-time and does not affect the underlying connection — all messages are still received, just not displayed.

What is the difference between WS and WSS?

WS (WebSocket) uses an unencrypted connection over plain TCP, while WSS (WebSocket Secure) uses an encrypted TLS connection over TCP. WSS is the WebSocket equivalent of HTTPS — it encrypts all data transmitted between the client and server, preventing eavesdropping, tampering, and forgery. In production environments, you should always use WSS (just as you should always use HTTPS for web traffic). WS is acceptable for local development and testing on `localhost`, but should never be used for production traffic over the internet. The tool supports both protocols, but remember that browsers enforce mixed content blocking — an HTTPS page can only connect to WSS endpoints, not WS.

Can I test authentication and headers?

The WebSocket API in browsers does not support custom HTTP headers during the handshake (unlike the fetch API or XMLHttpRequest). This is a limitation of the browser's WebSocket implementation, not of our tool. To pass authentication information, use one of these approaches: include a token in the URL query string (`wss://server.com/ws?token=abc123`), use cookies (which are sent with the WebSocket handshake if they match the server's domain), or send an authentication message immediately after the connection is established. For advanced header manipulation, use a desktop WebSocket client like Postman, wscat, or a custom script with a WebSocket library that supports custom headers.

Is my WebSocket testing data private?

The tool runs entirely in your browser. It does not proxy your WebSocket connections through our servers — your browser connects directly to the WebSocket server URL you specify. We do not log, store, or transmit your messages, server URLs, or connection metadata. The tool does not use analytics scripts to track which servers you connect to or what messages you send. All message logging happens locally in the browser's memory and is cleared when you close the tab. However, note that the WebSocket server you connect to can see your messages and connection information — the privacy guarantee applies only to our tool, not to the server you are testing.

Your Privacy is Our Priority

This tool runs entirely in your browser using the browser's native WebSocket API.

Your browser connects directly to the WebSocket server URL you specify — the tool does not proxy your connections through our servers, does not log your messages or server URLs, and does not transmit your testing data to any third party.
All message logging, filtering, and heartbeat management happens locally in the browser's JavaScript engine and memory.
The tool does not use analytics scripts to track which servers you connect to, what messages you send, or how long your sessions last.
When you close the browser tab, all connection data, message logs, and heartbeat configurations are cleared from memory immediately.
However, please note that the WebSocket server you connect to can see your messages, connection metadata, and IP address — the privacy guarantee applies only to our tool, not to the server you are testing.
Always use WSS (encrypted WebSocket) for sensitive data and never send production credentials through a testing tool.

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Test and debug WebSocket connections without installing anything

How to use

Enter Server URL

Establish Connection

Send Messages

Monitor Responses

Disconnect