VolumeMaster Audio Control by Sushi1337

VolumeMaster gives you precise control over the volume of the currently active Firefox tab, from 0% to 600%. It is designed for quickly boosting quiet videos, streams, podcasts, or calls without changing your entire system volume.

The add-on keeps the experience simple and focused. Open the popup, set the volume you want, and use convenient presets for common levels. You can also mute the tab instantly or reset it back to the default 100% level.

Volume is controlled per tab, so you can adjust only the content you care about without affecting everything else playing in your browser. A toolbar badge also shows when a tab is running above or below the default volume, making it easy to spot changed tabs at a glance.

Until recently, I personally used the 600% Sound Volume extension, but it was blocked because of malicious code concerns. That is why I decided to build my own alternative: one that stays focused on the single feature I actually wanted, without unnecessary extras or questionable behavior.

VolumeMaster is 100% ad-free, 100% tracking-free, and 100% open source. It is built to be lightweight, transparent, and easy to inspect.

VolumeMaster also stores interface preferences such as theme and accent color, so the popup feels consistent and pleasant to use over time.

Note: Volume levels above 100% rely on Web Audio API gain amplification. Depending on the source, very high levels may introduce distortion. The add-on is mainly intended for standard websites that use HTML audio or video elements, and some custom media players may behave differently.

The source code for VolumeMaster is fully open source and available on GitHub:
https://github.com/Sushi1337/VolumeMaster

If you find a bug or the add-on does not work correctly on a specific website, feel free to open an issue there. Feature requests, improvement ideas, and general feedback are also very welcome.