https://unhook.app/ - Remove recommandations from YouTube (so you can still used and watch it without getting into rabbit holes or end up procrastinating)

Colour Contrast Checker - Good when developing, always being able to check contrast between text/background to keep it accessible

LeechBlock - Limit the time on specific websites

BitWarden - Password manager

TextBlaze - Canned messages, good if you often respond to emails with the same message.