Never use 7z, because I do design work for a living and sending things to clients should be as trouble-free as possible - lots of corporate setups don’t allow additional programs to be installed, so zip files are a baseline for things that everyone, anywhere, can open. People have enough trouble trying to understand a WeTransfer download link, let alone some bizarro file format that could be flagged by their antivirus.
Channel Blocker for YouTube. Stop all those horseshit channels from reappearing in your suggestions.
Control Panel for Twitter. Allows you to customise your homepage by removing / changing parts of the UI, blocking ads and whatnot.
Save webP as png / jpg. Right-click to save those fucking awful files as something you can actual use.
Unwanted Twitch. Add channels / games / tags and keywords to a universal blacklist that stops them from appearing in the ‘Browse’ or recommended sections. Great for filtering out mince like IRL streams, shit like LoL etc. and chud streamers.