One feature I wish HIBP had was support for sub-domain addressing [1] and plus addressing [2].

My main email address has the format 'example@fastmail.fm' and receives alerts from HIBP if found in a data breach, but all of the related subdomain-based email addresses do not (e.g. netflix@example.fastmail.fm, google@example.fastmail.fm etc.)

Based on the 1Password screenshots in the linked article it would appear that specific support for sub-domain/plus addressing may not be required?

However, Firefox Monitor looks like it has the same limitations as the HIBP website/API and makes the alerts somewhat less useful when using sub-domain/plus addressing.

[1] https://www.fastmail.com/help/receive/addressing.html

[2] https://haveibeenpwned.uservoice.com/forums/275398-general/s...