Connect, inspect, mock, and debug WebSocket connections and Server-Sent Events (SSE) streams in real time.
Connection Endpoint
Disconnected
Notice: Browser specifications do not support setting custom headers for WebSocket connections. You can use subprotocols or query parameters (e.g. ?token=val) to authenticate.
Feature: Connecting in Header Mode uses a fetch-stream reader, supporting custom headers, POST request payloads, and cookies that standard EventSource objects reject.