A lightweight Firefox extension to set or boost the audio volume of an individual tab — up to 600% — without affecting any other tab. The level is remembered while you navigate within the tab and is cleared when the tab closes.
No ads, no tracking, no network access.
- Per-tab volume from 0% to 600% (boost past the browser's 100% cap)
- Doesn't affect other tabs
- Setting is cleared automatically when the tab closes
- Lightweight, vanilla JavaScript, Manifest V3
Available on Firefox Add-ons (pending review).
At or below 100% the extension sets the media element's volume directly. Above
100% it routes the element through a Web Audio GainNode to exceed the cap. All
processing happens locally in the page.
# Build the extension package
./build.sh # produces tab-volume-control.zipThen load it in Firefox:
- Open
about:debugging#/runtime/this-firefox - Load Temporary Add-on… → select
tab-volume-control.zip - Reload any audio tab so the content script is injected
On Flatpak/Snap Firefox, load the zip, not the unpacked folder — see Mozilla bug 1852990.
- Boosting above 100% on a cross-origin media file served without CORS headers produces silence (a Web Audio security rule). Staying at or below 100% always works, and major streaming sites are unaffected.
- DRM/EME-protected audio cannot be routed through Web Audio.