Browser extension for Firefox and Chromium browsers (Chrome, Brave, Edge) that records DOM snapshots of a page on demand and lets you browse and diff them like a wiki page history. Kaita is Lithuanian for change.
Nothing runs on any page until you click Record changes on it, so recording is opt-in per site. Snapshots are stored locally in IndexedDB and never leave the browser.
Kaita records the HTML of a page only while you have clicked Record changes on that page, and only for that tab. Snapshots are stored in the browser's local IndexedDB on your device. Nothing is transmitted anywhere: the extension makes no network requests of its own, has no analytics, no accounts and no third-party services. Clear a tab's history with Clear collected history, or remove everything by uninstalling the extension.
The Page tab in the viewer renders a snapshot in a sandboxed frame; the frame may load stylesheets, images and fonts referenced by the snapshot from the original site, exactly as a normal visit to that page would.
- Open the page you want to watch and click the toolbar button.
- Record changes takes a snapshot immediately and then one after every burst of DOM mutations. The same button becomes Stop recording. A snapshot is the page's live DOM as HTML, including form state the markup alone does not carry (ticked boxes, typed values, chosen options); password fields are never captured.
- View changes opens the history viewer for this tab.
- Clear collected history deletes this tab's snapshots.
The left pane lists revisions with time, delta to the previous revision and
size; the old / new radio columns pick the pair to compare, defaulting to
the last two. j / k move the new selection, Shift + j / k move
old. Diff shows a unified line diff of the pretty-printed HTML with
unchanged regions collapsed to three lines of context; Source shows the
new snapshot; Page renders a snapshot in a sandboxed frame (scripts
disabled). Click any row to view that revision as a page without touching
the old / new diff selection; the old / new switch above the frame
goes back to following the diff selection. The snapshot is the DOM only:
inline styles are exact, but external stylesheets, images and fonts are
fetched from the live site, so the render can differ if the site has
changed them since. Export downloads the new snapshot as
<timestamp>.html.
The list refreshes every two seconds while the tab is still recording.
One Manifest V3 codebase serves both browser families. Firefox uses
background.scripts, Chromium uses background.service_worker; each ignores
the other's key. All extension code goes through
globalThis.browser ?? globalThis.chrome, so no polyfill is needed.
Firefox: load the kaita/ directory via about:debugging → This Firefox
→ Load Temporary Add-on and pick kaita/manifest.json.
Chrome / Brave / Edge: open chrome://extensions, enable Developer mode,
click Load unpacked and pick the kaita/ directory.
npm install
npm run lintnpm run lint runs eslint . and web-ext lint; both must report zero
errors. npm run build packs kaita/ into web-ext-artifacts/ for store
submission; see STORE.md for the listing checklist.
kaita/icons/icon.svg is the only source. The PNGs the manifest references
are generated from it with npm run icons, which needs rsvg-convert
(librsvg). Edit the SVG, re-run the script, commit both.
npm run demo regenerates demo/demo.mp4, demo/demo.gif and the store
screenshots in demo/screenshots/ by driving a headless Firefox
(FIREFOX_BINARY, default firefox on PATH) through the extension on
https://todomvc.com/examples/javascript-es6/dist/, then stitching the
frames with ffmpeg. A toolbar popup cannot be opened by automation, so
the script loads the real popup.html in a tab bound to the demo page,
clicks its buttons there and composites that rendering over the page
frame; a copy of the extension with <all_urls> stands in for the
activeTab grant. The extension code itself runs unchanged.
kaita/vendor/diff.js is lib/index.mjs from the
diff package, version 7.0.0, copied
byte-for-byte with npm run vendor:diff. Never edit it by hand; bump the
pinned version in package.json and re-run the script instead.
MIT, see LICENSE. The vendored diff library is BSD-3-Clause.