WebSocket Tester

How do I test a WebSocket connection in the browser?

AnyTool WebSocket Tester opens a ws:// or wss:// connection straight from your browser using the native WebSocket API, then lets you send text or binary frames, watch a live frame log, and auto-reconnect. The page talks directly to your server - no proxy, no backend, nothing leaves your device.

Connect to any wss:// (or ws://localhost) and send text or binary frames
Live virtualized frame log with direction, timestamp, size and JSON pretty-print
Auto-reconnect with exponential backoff plus an app-level latency HUD
100% in your browser - no upload, no signup, works offline

What is

A WebSocket tester is a tool that opens a live ws:// or wss:// connection to a server so you can send messages and inspect every frame the server returns in real time, to debug realtime APIs.

Developer Tools

Related terms

WebSocketwss:// vs ws://SubprotocolsRealtime API debugging

Frequently Asked Questions

No. AnyTool runs entirely client-side and uses the browser native WebSocket object, which connects straight from the page to the target server. There is no AnyTool backend and no proxy in the path, so your URL, messages, and responses never touch our servers.

No. The browser opens the socket directly to your endpoint; AnyTool never proxies, stores, or logs any frame.

Yes. The composer has a binary mode that accepts hex, base64, or UTF-8 input and sends it as a real binary frame. Received binary frames are decoded and displayed with both a hex dump and a base64 view, alongside text frames in the same live log.

Yes. You can send binary as hex, base64, or UTF-8, and incoming binary is shown as hex plus base64.

The browser WebSocket API only accepts a URL and an optional list of subprotocols, so no tool running in a browser can inject Authorization, Origin, or Host headers. Desktop apps like Postman can do this only because they bypass the browser sandbox. Authenticate instead with a ?token= query parameter or a subprotocol token.

Browsers forbid custom WebSocket headers; only the URL and subprotocols are allowed, so authenticate via a query token or subprotocol.

Open the reconnect and heartbeat settings, toggle auto-reconnect, and the tool will retry a dropped socket with exponential backoff plus full jitter, capped at ten attempts, showing a live countdown. The app heartbeat sends a payload you choose on an interval and times the echoed reply so you see real round-trip latency.

Turn on auto-reconnect for exponential backoff with jitter, and enable the app heartbeat to measure round-trip latency.

Detailed Explanation

Technical Details

How a browser-based WebSocket tester works

AnyTool WebSocket Tester uses the browser native WebSocket object to open a connection directly from the page to a ws:// or wss:// server. Because WebSocket handshakes are not subject to CORS or the same-origin policy the way fetch is, the tool can reach any third-party endpoint with no proxy or backend. Sent and received frames stream into a virtualized log that stays smooth even at thousands of messages per second.

Uses the native browser WebSocket API, no library required
WebSockets are exempt from CORS, so any reachable endpoint works directly
Frame log is virtualized and ring-buffered to cap memory at 5000 frames per tab

Use Cases

Key features and frame handling

The tester sends text or binary frames, where binary can be entered as hex, base64, or UTF-8 and incoming binary is rendered as both hex and base64. It detects and pretty-prints JSON, supports Sec-WebSocket-Protocol subprotocols, and offers configurable auto-reconnect with exponential backoff and full jitter. A telemetry HUD tracks round-trip latency, messages per second, total messages, and bytes in and out, and sessions can be exported as JSON or NDJSON.

Text and binary frames with hex, base64, and UTF-8 encoding
Auto-reconnect uses exponential backoff with jitter, capped at 10 attempts
Multiple connection tabs, message templates, send history, and session export

Limitations

Honest browser limits

A browser sandbox imposes real constraints the tool surfaces in the UI rather than hiding. Custom request headers such as Authorization or Origin cannot be set because the WebSocket constructor only accepts a URL and subprotocols, so authentication must use a query token or subprotocol token. Plaintext ws:// is blocked from the secure HTTPS page by mixed-content rules, so only wss:// or ws://localhost works, and the heartbeat is an application-level ping because browsers hide protocol-level ping and pong control frames.

No custom headers; authenticate via ?token= query param or subprotocol
ws:// is mixed-content blocked from an HTTPS page; use wss:// or ws://localhost
Heartbeat is an app-level ping since browsers do not expose protocol ping/pong

AnyTool WebSocket Tester vs typical online alternatives
Capability	AnyTool	Typical alternative
Privacy / no upload	Yes - 100% client-side, direct browser to server	Often account-gated or SEO-hub funnels
Price / signup	Free, no signup, no API key	Freemium, signup or API key common
Auto-reconnect with backoff	Yes - exponential backoff plus jitter	Usually missing in free testers
Binary frames	Yes - hex, base64, and UTF-8	Many free web tools skip binary
Latency HUD and multi-tab	Yes - app-level RTT and side-by-side tabs	Rare or single-socket only

Native desktop apps can set custom headers a browser cannot; that is a browser-sandbox limit, not a feature gap.