Server-Sent Events (SSE) Tester
Stream text/event-stream endpoints with custom headers and POST bodies — including LLM streaming APIs. Straight from your browser to your server.
Help shape Server-Sent Events (SSE) Tester
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Frequently Asked Questions
EventSource can't send headers like Authorization, can't POST, and only reports events you subscribe to by name. This tester streams over fetch, so headers, POST bodies and every event name just work.
Yes. Choose POST, add your Authorization and Content-Type headers, paste the JSON body and connect. Each streamed chunk appears as an event you can inspect or export.
Yes. When the stream ends or drops, it reconnects with exponential backoff and sends Last-Event-ID so the server can resume where it left off.
Usually CORS: the server must send Access-Control-Allow-Origin for this site, and custom headers need a successful OPTIONS preflight. HTTP errors like 401 or 404 are shown with the response body.
Yes. Requests go directly from your browser to your endpoint. Nothing is proxied, logged or stored by us.