What are some of your must have browser extensions?

I recently made an effort to switch to Firefox, and now I'm looking for some good browser extensions to make my web browsing experience better. Here are the ones I currently use:

• HTTPS Everywhere
• Privacy Badger
• uBlock Origin
• Vimium

I posted about it three days ago but in these last three days I really worked my ass off to include lots of functionalities and feel like the community is missing a lot of topics...
So, sorry, I won't spam this for the next days every three days but I felt like it deserved to be "bumped" in the activity feed at least once now that the default is just 24h.

As of today, the features are:

• management to choose which links top open in a new tab
• button to quickly jump to new comments in a topic
• button to quickly get back to the top of the page in topics (no, there isn't one to go to the bottom)
• live preview of the reply/topic box
• load external CSS to customize the UI
• add label to users

I'll just link to the original topic so you can have some context if you want, otherwise these are just the links to download it:

• Original Topic: https://tildes.net/~tildes/1oa/browser_extension_tildes_extended
• Chrome: chrome.google.com
• Firefox: addons.mozilla.org
• Source: Github (feel free to do modification and open pull requests if you'd like!)

I need feedback to know what else you'd like to see implemented or what have bugs or could be done in a different/better way!