Soft U2F is a software-based implementation of the FIDO U2F second-factor authentication designed for macOS users, aiming to increase the adoption of this security measure. It is compatible with Google Chrome, Opera's built-in U2F, and U2F extensions for Safari and Firefox, allowing users to receive notifications to accept or reject authentication requests when visiting U2F-compatible sites. Users can experiment with the technology on Yubico's U2F demo site and configure it for use with their GitHub accounts. The initiative is detailed further in the Engineering Blog, where the motivations for the project and the differences between hardware and software key storage are discussed, offering insights into the security considerations involved.