How to Test a Socket.IO Server Online

Socket.IO Connector is a free, browser-based Socket.IO client tester. Point it at any server, emit events with JSON payloads, listen for replies and watch every message in a live log, with no Postman collection, no throwaway script and no install.

Test your server in four steps

1. Enter the server URL, for example http://localhost:3000 or https://api.example.com.
2. Set the socket path if your server doesn't use the default /socket.io.
3. Add the events you want to listen to and toggle each one on or off while you test.
4. Create emitters with an event name and a JSON payload, then send them with one click. Incoming and outgoing messages appear in the log with timestamps.

Features

Emit events with JSON payloads

Keep a list of ready-to-send events, each with its own payload, so you can replay the same request without retyping it.

Listen to any event

Subscribe to as many event names as you need and switch them on or off without reconnecting.

Real-time message log

Every incoming and outgoing message is logged with its direction and time. Open any entry to inspect the full payload.

Saved configurations

Save a server, its path, listeners and emitters as a named configuration. Switch between projects in seconds, and export or import configurations as JSON to share them with your team.

WebSocket with polling fallback

The client connects over WebSocket and falls back to HTTP long-polling, just like a production Socket.IO client.

Allow the tester in your server's CORS settings

Since Socket.IO v3, servers reject cross-origin browser clients unless you allow them. Add the tester's origin while you develop:

const io = new Server(httpServer, {
  cors: {
    origin: ["http://localhost:5173", "https://socket-io-connector.vercel.app"],
  },
});

Frequently asked questions

Is Socket.IO Connector free?

Yes. It runs entirely in your browser, needs no sign-up and no install.

Can I test a Socket.IO server running on localhost?

Yes. The connection is made directly from your browser, so a URL like http://localhost:3000 works as long as the server is running on your machine and its CORS settings allow the tester's origin.

Why does my connection fail with a CORS or timeout error?

Socket.IO v3 and later block cross-origin clients by default. Add https://socket-io-connector.vercel.app to the cors.origin option of your Socket.IO server, check that the server URL and path are correct, and make sure an https page is not connecting to a plain ws:// server that the browser blocks as mixed content.

Does it work with a custom Socket.IO path?

Yes. Set the Socket Path field to whatever your server uses, for example /api/socket.io instead of the default /socket.io.

Where are my configurations stored?

In your browser's local storage. Nothing is sent to a third-party backend. You can export configurations to a JSON file and import them on another machine.