Here are open-source authentication tools for sign-in, SSO, and identity management. Keycloak provides identity and access management with single sign-on and multi-factor authentication. Authelia adds an SSO multi-factor portal for web apps, and Lucia keeps auth libraries simple for application code. Compare them when you need login flows you can host yourself.
The most popular open-source Authentication tool by GitHub stars is Appwrite(55.7k stars), followed by Keycloak(33.8k stars)and Authelia(27.5k stars). This page lists the top 12 of 12 authentication tools in the directory, ranked by community adoption.
| # | Tool | Stars | Language | License |
|---|---|---|---|---|
| 1 | Appwrite Appwrite is an open-source backend server for Web, Mobile, and Flutter developers. It provides a set of easy-to-use REST APIs for managing authentication, databases, storage, and more. | 55.7k | TypeScript | BSD 3-Clause "New" or "Revised" License |
| 2 | Keycloak Open Source Identity and Access Management solution for modern applications and services, offering single sign-on, user federation, and multi-factor authentication. | 33.8k | Java | Apache License 2.0 |
| 3 | Authelia Authelia is a Single Sign-On Multi-Factor Authentication portal for web apps, providing secure and streamlined access management. | 27.5k | Go | Apache License 2.0 |
| 4 | Server Bitwarden infrastructure and backend solution for managing API, database, and Docker environments. | 18.4k | C# | Other |
| 5 | Zitadel ZITADEL is a modern identity infrastructure that simplifies authentication and authorization for developers, providing advanced features like multi-factor authentication and single sign-on. | 13.5k | Go | GNU Affero General Public License v3.0 |
| 6 | Fastapi_mcp Enhance your FastAPI application by exposing endpoints as Model Context Protocol (MCP) tools, complete with authentication support. | 11.8k | Python | MIT License |
| 7 | Lucia A user-friendly authentication library designed to be simple and clean for developers. | 10.5k | — | BSD Zero Clause License |
| 8 | Nhost Nhost is an open-source platform providing a Firebase alternative with GraphQL support. | 9.1k | TypeScript | MIT License |
| 9 | OpenAuth OpenAuth is a universal, standards-based authentication provider designed to simplify secure authentication for applications. | 5.7k | TypeScript | MIT License |
| 10 | Authgear-server authgear-server is an open-source authentication server that serves as an alternative to Auth0 and Firebase Auth. It provides secure, flexible, and scalable user authentication and identity management for web and mobile applications. | 1.6k | Go | Apache License 2.0 |
Appwrite is an open-source backend server for Web, Mobile, and Flutter developers. It provides a set of easy-to-use REST APIs for managing authentication, databases, storage, and more.
Open Source Identity and Access Management solution for modern applications and services, offering single sign-on, user federation, and multi-factor authentication.
Authelia is a Single Sign-On Multi-Factor Authentication portal for web apps, providing secure and streamlined access management.
Bitwarden infrastructure and backend solution for managing API, database, and Docker environments.
ZITADEL is a modern identity infrastructure that simplifies authentication and authorization for developers, providing advanced features like multi-factor authentication and single sign-on.
Enhance your FastAPI application by exposing endpoints as Model Context Protocol (MCP) tools, complete with authentication support.
A user-friendly authentication library designed to be simple and clean for developers.
Nhost is an open-source platform providing a Firebase alternative with GraphQL support.
OpenAuth is a universal, standards-based authentication provider designed to simplify secure authentication for applications.
authgear-server is an open-source authentication server that serves as an alternative to Auth0 and Firebase Auth. It provides secure, flexible, and scalable user authentication and identity management for web and mobile applications.
Easily add authentication to your React applications using React Query, providing a seamless integration for secure and efficient login flows.
Simplify your authentication flow when working with React applications, enhancing security and user experience.
Appwrite leads by GitHub stars(55.7k). Appwrite is an open-source backend server for Web, Mobile, and Flutter developers. It provides a set of easy-to-use REST APIs for managing authentication, databases, storage, and more.
Yes. Every tool on this list is open source and free to use in your own projects. Many can be self-hosted.
Tools are ranked by GitHub star count, a strong proxy for community adoption and active maintenance. Star counts are refreshed regularly.
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