Volume Booster от fivefm

Some sites are just too quiet. Volume Booster puts a slider in your toolbar that pushes any page's audio and video past the 100% ceiling, up to 600%. It also turns things down when a site is too loud.

What you get

• Boost from 0% to 600% with a slider, or tap a preset: 150%, 200%, 300%, 400%, 600%
• Per-site memory. Set YouTube once and it stays that way, while every other site keeps its own level
• A toolbar badge that shows the current boost, so you always know when it's on
• Works on every audio and video element on the page, including embedded players and iframes
• Follows your Firefox theme, light or dark

Privacy

Volume Booster collects nothing. No accounts, no analytics, no network requests. Your per-site levels are stored locally in Firefox.

Good to know

• DRM-protected streams (Netflix, Spotify, Disney+, Prime Video) can't be boosted. Firefox mutes Web Audio for protected media, so the add-on skips them and tells you in the popup.
• Cross-origin media without CORS headers is skipped for the same reason. YouTube, Twitch and most video players work fine.
• Firefox doesn't let add-ons run on some pages, such as about: pages, addons.mozilla.org and Reader View.
• High boosts clip and distort. Look after your ears and your speakers.

How it works

Each media element is routed through a Web Audio gain node. Pages are left untouched until you set a site to something other than 100%.