TOTPRadius is described as 'A simple and cost-effective way to provide secure, policy-compliant and user-friendly on-premises two-factor authentication solution with self-enrollment'. There are more than 25 alternatives to TOTPRadius for a variety of platforms, including Online / Web-based, Self-Hosted solutions, SaaS, Windows and Linux. The best alternative is Keycloak, which is both free and Open Source. Other great apps like TOTPRadius are Auth0 (Freemium), FreeIPA (Free, Open Source), LoginRadius (Paid) and FusionAuth (Paid).
Authpack provides a complete user and team management API and Dashboard installed with just 8 lines of code and featuring a built-in API explorer for developers to easily perform complex GraphQL operations on data from inside the app.