Interesting idea! I did a quick look through your site and have a few issues: 1. What MFA methods do you support? TOTP? App based auth? U2F? FIDO2? (FIDO2 USB? BLE? Platform authenticators?) Smart cards (especially for enterprise)? Backup OTP's? New device detection? 2. Your docs mention not playing nice with password manager autofill by default. Are there plans to address this? 3. Password reset emails come from @su…
Now you've got WebAuthn's anti-phishing protection for the actual login, but that protection extends no further. As the native authentication of a site (e.g. Google, GitHub, Facebook) that's fine. But for a third party helper that's a problem.
Say I intend to visit my hypothetical WebAuthn enabled bank. If I go to https://fake-bank.example/convincing-phishing-page/ there is no way for them to get my real-bank.example credentials. The browser vendor is responsible for making sure this is true.
But now suppose they use "Super Tokens" instead, and I protect my "Super Tokens" with WebAuthn. I go to https://fake-bank.example/convincing-phishing-page/ and the bad guys who run it only need to fool "Super Tokens" into giving them a working token for my real bank. I authenticate with WebAuthn to Super Tokens and so that's working fine, but any flaws in the Super Tokens backend or implementation, out of my control, put me at risk. Not great news.
And this has already happened (as proof of concept anyway), to existing players in the space. It's categorically less safe to do this.