- https://webauthn.io a neat demo,
- https://webauthn.guide gives a brief (technical) introduction, and
- https://developer.mozilla.org/en-US/docs/Web/API/Web_Authentication_API provides a longer overview of
- the Web standard defined on https://w3c.github.io/webauthn.
- (https://developers.yubico.com/WebAuthn/ has more detailed information.)
It works well in current versions of desktop browsers, and on mobile on Chrome on Android. (But tere is currently no easy way in the FOSS community to use U2F in an Android browser; see here, but note this.)
Web Crypto API is an unrelated standard.