Validating Leaked Passwords with k-Anonymity - from #CloudFlare blog, 2018:

https://blog.cloudflare.com/validating-leaked-passwords-with-k-anonymity/

@buherator

Or just download the entire Pwned Passwords hash corpus (SHA1 or NTLM) and use it yourself locally:

https://github.com/HaveIBeenPwned/PwnedPasswordsDownloader

You can use them for local checks, or even try to crack them yourself, or download all the founds from people who have:

https://hashmob.net/hashlists/official

At this writing, Hashmob has cracked about 99.3% of them.