Is there any option/extension available for searching your own favorites by tag, so you can look for a specific thing you've favorited? I know a similar user-made extension exists for Rule34.xxx and I was wondering if anyone has made anything like that for realbooru.

I second the motion

Still looking for something that would do this...

Maybe when the next version of the site software gets released, whenever that is.

at one point you could just filter your search with "fav:(user id)" but a couple months ago it got removed or stopped working

Someone made a tool for searching favorites on Rule 34. Wish they also made one for Realbooru.