Troy Hunt already nailed the perfect service and API. Google's solution here is not documented, and clearly not as usable as Troy's [0] (anyone with openssl(1)+curl(1) can check if they've been pwned right from the CLI [1])

[0] https://haveibeenpwned.com/API/v2#PwnedPasswords

[1] https://gitlab.com/moviuro/pass-hibp/blob/master/hibp.bash