krill.to

krill.to is full-text search for your X (Twitter) bookmarks. Connect your account and it imports and indexes everything you've saved.

X ships no real bookmark search. You can save posts, but finding them later is almost impossible: no full-text search, no filtering by date or topic, just a chronological dump.

I built it for myself after failing to find a third-party tool that actually worked. It's free to use.