Google Titan - A 2FA device to protect yourself from hackers
Instant 2FA - Add two-factor auth to any site in minutes
Base API - API for authentication, email sending, images and more!
1Password - 1Password can create strong, unique passwords for you, remember them, and restore them, all directly in your web browser.
TwoBlocks - A 2FA provider on BlockStack
Authentiq - Strong authentication, without the passwords