ID.me

ID.me is both a verification service and a reusable identity. A person verifies once (document, selfie, sometimes a video call with a trusted referee) and then uses their ID.me login to prove identity, age, or group membership (veteran, student, first responder) at any site that accepts it. It's the identity provider for many US federal and state agencies.

For a platform, it's a way to accept a high assurance credential without running verification yourself, particularly for US users.