Naven
Answers
Does Naven cost anything?
No. It is free, with no advertising, no paid tier and no data sale. It is paid for by the person who builds it.
There is no premium plan, no feature held back, and no limit that a payment removes. That is stated in the site's structured data as well as its marketing, which makes it checkable.
The honest caveat is what that funding model implies: Naven is run by one person, and that is a real constraint on support, on response times and on how fast things get fixed.
It is stated on the site rather than discovered later.