[esamatti]

Hash the phone number in the browser before sending it to your server. That way it is at least possible to verify via devtools what is being send.

Heck. Allow even prehashed phone number to be entered.

[brigandish]

I understand the frustration but they have the data and hence, a rainbow table, sending a pre-hashed phone number is the same as sending an unhashed one, unless the worry is man in the middle, who is just as likely to get the data.

The only way to check without giving up personal info is to get the data and look locally, or perhaps search for so many phone numbers that yours is buried in the haystack.

[bra1n]

That only holds for numbers already part of the dump. If you submit an unknown phone number that is not contained in the leak, hashing it before sending it will increase data privacy.

[MarcoBuster]

That's what we're planning to do. Thank you