Searching for "pdf search" isn't finding anything significant.
"PDF drive" (https://news.ycombinator.com/item?id=25240373, 0 comments) just appears to be an ebook crawler over in the less-than-#FFFFFF-department if you get what I mean.
I also found a thread talking about searching PDFs for specific queries (https://news.ycombinator.com/item?id=10154527) which appears to have generated some interesting results back when the thread was posted, in 2015.
Not seeing anything recent though. But on the subject of a search engine specifically for finding redacted content, I couldn't help but imagine the discussion...
"Hi, I would like to find a •••••••."
"You specifically want a •••••••?"
"Yes, literally."
[Person 2 walks away scratching their head wondering what person 1 would do with a 'hunter2']
Re:Horrifying PDF Experiments
by trevinhofmann on Saturday January 02, 2021 @07:13AM
(#25612267)
You might be remembering `Google PDF Search: “not for public release”` from 2015 [1] and 2019 [2].
Wasn't there a search engine built into finding redacted PDF content? I think it made the headlines here a while back.