At the moment, there doesn't seem to be a way to search only the titles that I own, either by keyword or by tag.  It would be extremely helpful, in these days of big bundles, to be able to perform a 'My Library" search in a similar to way to standard searches.

now that would be helpful. on steam you always see that a game is in your library, if you browse games. and you can checkbox away your libray and wishlist. itch only tells you taht a game is in your collection if you try to add it to a collection.