Simple, clean & free. Works great!
Only thing I wouldn't mind seeing added is +/- buttons to adjust the dB's besides clicking & dragging the slider with mouse.

Edit: Thanks Dev! The many hours on the update is much appreciated!

doesn't work for me, unfortunately

Works immediately to boost volume with no quality loss. Doesn't ask for suss permissions like other add-ons claiming to achieve the same thing.

This works very well and all, but there is a very important feature that I have noticed is missing, the ability to save preset volumes for specific websites.

Actually all this thing did was cause the sound to cut-out to nothing when I clicked the add-on's button on the firefox toolbar. I had a video with sound but when I click the button I had no sound. Using the db slider seemed to have no affect. Didn't work for my situation but maybe it works for other people in their situation.

This worked perfectly for me. I'm taking a Udemy course where the volume was too low on some videos, and this allowed my to adjust my browser volume while keeping all other system sounds at the same level.

clean, simple and works as stated in desc

При обращении к нему (дополнению) пропадает звук на странице просмотра. Пробовал перезагрузить страницу и переустановил дополнение - одинаково бездарное барахло.

Brilliant. Especially useful in raising volume on quiet Twitter Spaces like Mriya Report.

excellent for resolving pb issue sound thks

Not only did it not boost the volume, it completely removed it. No matter where I slid it, up or down, it completely obliterated my laptop volume so I could hear nothing.

works really well and open source

Super love the fact that it's open-source. I suggest adding a key bind to open the popup so that the users don't have to scroll to the upper right to adjust the volume.