Open-source alternatives offer extensive customization through public code access. Most of them provide free / paid cloud service. Some might require self-hosting to use.
A flexible platform providing single sign-on and multi-factor authentication to enhance security for web applications
Authelia is a robust open-source authentication and authorization server designed for identity and access management (IAM). It provides single sign-on (SSO) capabilities and multi-factor authentication (MFA) for secure access to applications, all while integrating seamlessly with common reverse proxies.
A flexible platform for centralized access management, supporting SSO, MFA, and various authentication protocols
Authentik is a powerful identity provider (IdP) and single sign-on (SSO) platform designed to provide secure, centralized access management across environments. It supports multiple authentication standards, including OAuth2, SAML, LDAP, and SCIM, allowing it to integrate seamlessly with various applications. With a user-friendly admin interface, Authentik simplifies user, group, and application management.
A flexible solution for secure single sign-on (SSO) and user authentication, ideal for web applicationsPostgreSQL database, authentication, and real-time capabilities
Keycloak is an open-source identity management platform that enables secure authentication, SSO, and role-based access control (RBAC) across multiple applications. With support for social logins, multi-factor authentication, and customizable login flows, Keycloak centralizes user management, making it easy to secure access without relying on third-party services.
Empower your applications with flexible and secure authentication, authorization, and user management, tailored to meet your organization’s needs.
Ory provides a modern, modular identity and access management (IAM) solution designed for flexibility and scalability. It enables seamless integration with various applications through Single Sign-On (SSO), social logins, and passwordless authentication, all while offering customizable user interfaces and workflows.
A open-source platform enabling secure user authentication and authorization with customizable options for any web or mobile application
SuperTokens provides an open-source, self-hosted authentication solution focused on simplicity and scalability. It supports common authentication methods, including passwordless login, social login, and single sign-on (SSO), and integrates easily with existing applications. Designed to prevent vulnerabilities, SuperTokens offers comprehensive attack protection and ensures secure user access.
A versatile solution enabling developers to implement secure, passwordless authentication using passkeys, alongside support for email passcodes and optional passwords
Hanko is an open-source authentication and user management system that emphasizes modern, secure login methods. It facilitates the integration of passkeys—an advanced, passwordless authentication technology—into applications, enhancing both security and user experience. Additionally, Hanko supports email passcodes and offers optional password integration, catering to diverse security requirements.
A customizable identity infrastructure designed to streamline authentication and authorization for applications of any size
Zitadel is a powerful identity management platform that simplifies authentication and authorization processes across applications. It supports various modern authentication methods, including Single Sign-On (SSO), social logins, and passwordless authentication, while offering a customizable hosted login page and robust APIs for seamless integration.
A developer-friendly platform that provides a suite of open-source tools for backend development, including PostgreSQL database, authentication, and real-time capabilities
Supabase is an open-source backend-as-a-service (BaaS) that empowers developers with a PostgreSQL database, real-time data sync, and authentication out of the box. It offers SQL-based storage, allowing developers to use familiar SQL commands while benefiting from Supabase’s real-time API, enabling seamless updates across clients. With its authentication service, Supabase supports multiple authentication providers, making it simple to implement secure user management for web and mobile applications.
If you are looking for more features or an enterprise solution, you might want to consider closed source alternatives. Some of them has decent free tier.
A robust BaaS platform that offers a suite of tools and infrastructure for building, testing, and scaling applications
Firebase is a cloud-based platform by Google that supports app developers with powerful tools to manage the backend of their applications without needing extensive infrastructure. Its features include a real-time database, user authentication, and cloud storage, providing a scalable solution for data management, file storage, and user management. With integrated analytics and performance monitoring, Firebase gives developers valuable insights into user behavior, helping them improve app performance and engagement.
A comprehensive authentication and authorization platform for secure app access