Instead of improving their bookmarks feature by adding category and search, Twitter focused on Fleets instead 🤡
I got frustrated by Twitter for not having category and search for bookmarks, hence I made one myself. I showed it to a few friends who also bookmarks a lot, and they got excited, so I think it might be useful for you as well.
"I always wanted to have something like this!" - Tibor Bödecs
(Author of The.Swift.Dev)
As Twitter doesn't have API for accessing bookmarks (they don't allow third party app to read or add bookmarks for users), I have created a Twitter bot instead, which you can DM the bot with the tweet you want to bookmark, with the category/folder name you want.