Butterly by dedashev02

Butter makes Firefox smooth, private and yours.

Blocks ads and trackers with the same lists uBlock Origin uses (EasyList, EasyPrivacy, Peter Lowe, URLhaus), hides the empty spaces ads leave behind, and catches trackers hiding behind a site's own name. A built-in core list works before anything is downloaded.

Handles cookie pop-ups: clicks "Reject" for you on 40+ consent tools, then hides what is left.

Keeps your data yours: hides your real IP address in video calls, stops Firefox from contacting sites you did not open, sends the "do not sell my data" signal, cleans tracking codes (utm, fbclid, gclid and 90 more) from links, and stops other sites from learning which page you were reading.

Keeps Firefox quick: unused tabs go to sleep and free their memory, links skip the tracking detour through Google, Facebook, YouTube and others, and one click puts every other tab to sleep or closes duplicate tabs.

Every option explained in plain words, with a label that tells you whether it can change how websites look: Safe, Almost always safe, Sites may look different, or Can break some sites. You always know what you are switching on.

Yours to style: light or dark, 20 colour sets or your own colours, corner style, font and text size on all of Butter's pages.

Privacy: no account, no telemetry, no analytics. The only thing Butter ever downloads is the filter lists, straight from their publishers, and you can turn that off. Everything else stays in Firefox's local storage on your computer.

Open source (MIT).