Thanks to Chaython putting the source code on GitHub, you can check for yourself that everything's above board. The extension does exactly what it says on the tin!

this one actually works and should be at the top of the list.

Easy functionality for me, and worked like a charm thank you!

does what it says on the box

Thanks for the spectacular extension and link to source code; it is highly appreciated since most other "volume control" extensions on Firefox are sketchy or outdated. Works very well.

Pleasantly surprised after last experience with volume booster. This application rocks!

Far better than other sound addons. Does the job, doesn't broke the pages and no ads/clickbait.

Simple et efficace. Garde en mémoire le réglage effectuer pour les shorts suivant contrairement a d'autre extension qui reset le volume après un Skip. Je préfère.

Much better than other available volume extensions.

Honestly, really good, comparing to other volume-control add-ons.

Hulu seems to not load video unless this is disabled, but otherwise has been nice to use when volume sliders are missing from a site.

does exactly what its supposed to do.

Simple UI and works. I mostly use volume controls to LOWER the volumes. Every other extension is for raising the volumes so their UI for lowering the volume is robust and just mostly do intervals of 10 and sometimes having it that just 10 is still too high. So this extension fills all my needs and wants. Great work!