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Network

WebSocket and SSE Connection Tester

Connect to WebSocket or SSE endpoints and inspect a timestamped live transcript.

Free to use No sign-up Runs in your browser

Tool workspace

idle

The browser connects directly to the endpoint. EventSource cannot attach custom request headers.

Session transcript (0)

Connect to an endpoint to start the timestamped transcript.

What Is a WebSocket and SSE Tester?

This tester opens a browser connection to a WebSocket or Server-Sent Events endpoint and records lifecycle events, incoming data, outgoing WebSocket text, and errors in a timestamped transcript. WebSocket supports two-way messages, while EventSource receives server events over HTTP and relies on the browser's built-in reconnect behavior. Connections go directly from your browser to the endpoint you enter, so the remote service receives your network and request metadata.

How to Test a Real-Time Endpoint

  1. 1Choose WebSocket or Server-Sent Events, then enter a URL with the protocol required by that transport.
  2. 2Connect and watch the status plus timestamped lifecycle, message, close, and error entries in the transcript.
  3. 3For WebSocket, send text frames; for either transport, copy the transcript or export its messages as JSON.

WebSocket and SSE Testing Use Cases

Debug a WebSocket echo or API

Open a socket, send representative text frames, and verify the order and content of replies without writing a temporary client application.

Observe an SSE event stream

Connect with the browser EventSource API and monitor incoming event data, interruptions, and automatic reconnect attempts over time.

Capture a reproducible transcript

Export timestamped connection events and messages as JSON when documenting an integration issue or comparing server behavior.

Frequently asked questions

Can the SSE tester send custom headers?

No. The browser EventSource API does not expose a custom-header option. Use cookies, URL parameters, or a purpose-built client only when that matches the endpoint's security design.

Are endpoint URLs and messages processed locally?

The interface and transcript are managed in the browser, but connections and messages are sent directly to the endpoint you provide. Do not send secrets to a service you do not trust.

Why might a secure page reject my endpoint?

Browsers commonly block mixed content, so an HTTPS page usually needs wss:// for WebSocket and https:// for SSE. Endpoint CORS, authentication, and certificate rules also still apply.