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!

So it all begun as a [something]monkey script but I decided to give it a try to web extensions after several years of not touching it.

If you don't care about the yada yada, skip right at the bottom now.

Why

So the whole thing revolve around a simple concept: I'd like tildes to remain as lightweight as possible with a simple and clean interface and not too many user settings.
We don't know the full structure of the code yet but, by experience, frontend and backend require quite an effort to be kept in balance so that one or either don't becomes a mess.

From this idea, the next step has been quite obvious. Users that would like a more advanced frontend experience could just download an extension (probably an app for mobile once it becomes possible).

What

Right now the extension does some simple things. It is basically just a porting of the script I made some time ago so you'll get non-tildes link in a new tab and a button to jump to new comments in a topic you already visited.
The extension don't retain any user data. it doesn't care who you are or what you browse. If you're unsure you can check the source code (below).

Future Goals

The immediate priority is to create a "settings" page so you can customize how the features should behave. As an example, about the links in new tab, letting you decide which kind of links should behave like this: all / comment's / text submission's / etc etc. I'm still thinking which are reasonable use-case

After that, I want to try and implement a user's labelling system and that is the reason for the app already requesting access to storage data on the browser. I've yet to figure it out but the gist of it is that I'll store something like username:tag duplet in your browser localstorage and on load of a page, check for usernames match and add the label you choose.

Additional Notes

I know the code is dirty. As I said, I didn't touch extensions since... I think more than 6 years ago. Maybe more.
On top of that, I went for jquery and am more of a modern framework JS developer with a strong preference and background as backend developer, so... you know.
I still think I'll stick to jquery because the syntax is quite clear and I want even non-technical people to be able to understand what's going on in the code if they want to double check.

If you want to contribute you're more than welcome but keep in mind that most basic things are still missing. To mention just a couple:

• settings page
• proper isolation of content scripts
• guidelines or at least a sample to use to implement new features

if you have any resource that you used to build something similar (web extension or the like) please share them as I've a goddamn long commute every day and have time to read :)

Links

• Firefox: https://addons.mozilla.org/en-GB/firefox/addon/tildes-extended/
• Chrome: https://chrome.google.com/webstore/detail/tildes-extended/dinimcigfnjcblajimodbacmbknmicgl/related
• Source: https://github.com/theCrius/tildes-extended

It should work on any fork of Chrome as well.
I can't assure the same for future development.

Current features:

• Link in new tabs management
• Button to jump to new comments in topics
• Add custom CSS from external URL
• Markdown Preview
• Add User's labels