SSE DevTools Panel

Debug SSE / NDJSON / Connect+JSON streaming responses in a DevTools panel

SSE DevTools Panel is a Chrome DevTools panel for debugging streaming responses: SSE, EventSource, NDJSON, and Connect+JSON. Chrome Network already helps with standard SSE, but many product streams use fetch and custom protocols. Response data is often hard to read, timing is unclear, and chat-like payloads (thinking, content, tool calls, search sources) stay buried in raw frames. This extension gives you a dedicated workbench for those streams. What you get • Capture streams from fetch, EventSource, and XHR without changing how the page works • Streams sidebar with URL search and transport filters (Fetch / EventSource / XHR) • Events table with JSON tree, text/regex filter, resizable columns, and virtual scrolling • Request view for headers and body (sensitive headers such as Authorization / Cookie redacted) • Conversation view that merges stream fragments into Content / Thinking / Tools / Meta channels when the protocol is recognized • Timeline for arrival timing, stall highlights (≥250ms), gap distribution, and reconnect markers • Raw text view with one-click copy • Stats, Anomalies, Spec checks, and Search All across streams • Import / export (JSON, CSV, .sse fixture) and local archives • Light / Night / Follow DevTools theme (preference saved in Chrome sync) • English and Simplified Chinese UI Unrecognized streams still work in Events, Timeline, and Raw. Who it is for Developers building or debugging chat UIs, notification pushes, progress streams, and other long-lived streaming APIs in Chromium browsers (Chrome, Edge, and similar). How to use 1. Install the extension 2. Open your page → press F12 → open the SSE DevTools panel 3. Refresh the page, then trigger a streaming request 4. Pick a stream in the sidebar and inspect Events, Request, Conversation, Timeline, or Raw Notes • Chromium DevTools only (no Firefox / Safari panel yet) • Does not capture requests started inside a page Service Worker • Conversation merge depends on site protocols and may need updates when formats change • Data stays on your machine for debugging; the extension does not upload captures to our servers