API Diff

Save an API response as a baseline, refresh, and see exactly what changed.

Save an API response as a baseline. Refresh. See exactly what changed. API Diff adds an "API Diff" tab to Chrome DevTools. As your page makes JSON requests, they appear in the panel. Pick one, save it as a baseline, and the next time it is called API Diff compares the new response with your baseline and lists what is different. What it shows Fields that were added, removed or changed, and fields whose type changed Breaking changes (a removed field or a changed type) marked separately from harmless ones Arrays compared by item, not by position, so a list that only came back in a different order is reported as one "Reordered" line instead of dozens of false changes A list of fields to ignore (timestamps, request IDs) and a "schema only" mode that compares structure and types but not values Copy the result as Markdown to paste into a pull request or a ticket Built for large responses: comparisons run in the background, so DevTools stays responsive. Your data stays on your computer Baselines are saved in your browser's local extension storage. API Diff does not send anything to any server, has no account, and contains no analytics or ads. Page capture (optional, per site) The DevTools panel works on every site with no extra access. If you want API Diff to also see the page's own fetch and XHR responses, you can turn on "page capture" for a single site from the toolbar icon. Chrome asks you each time, and you can turn it off again at any time. Until you do, the extension has no access to any website.