NOTE: - Since there was no listing for the official extension and the maintainer of the other port of this extension on Firefox had abandoned updates, the extension was very outdated so I decided to maintain it myself! Source code is here - https://github.com/dimdenGD/OldTwitter Features

Almost all of Twitter functionality is implemented
Both reverse chronological and algorithmical timelines support. And exclusive: Reverse chronological timeline with friends likes and follows (basically mix of both chrono and algo timelines)
Custom profile link colors supported
You can change custom profile link color and it'll appear for other extension users (priority: oldtwitter color db -> twitter color db -> default color)
Removes all analytics and tracking from Twitter
Track your unfollowers for free
Search, sort and filter your followers
Removes all ads
Easy download of videos and GIFs
Translate tweets without having to open them, also ability to set specific users/languages to autotranslate
Shows why tweets were added to algorthimical timeline
Dark mode support
Ability to enable/disable Twemoji, disable stars (favorites) back to likes (hearts), change font, default link color and any other color in extension
Lot of hotkeys
Mobile support with Kiwi Browser or Firefox
Custom CSS support