Open Source Alternatives to FusionAuth

An authentication and user management software that secures access for humans, services, and AI across any environment. The platform provides identity capabilities via API to integrate into products, pipelines, and workflows, supporting high scale B2C, B2B, B2B2C, and machine-to-machine identity models. It includes features for multi-factor authentication, breached password detection, and fine-grained authorization using RBAC, ABAC, and ReBAC. The software is designed for engineering teams running critical systems and can be deployed as a self-hosted, dedicated, on-prem, hybrid, or air-gapped installation to meet regulatory and data sovereignty requirements. It supports industry standards such as OAuth 2.0, OpenID Connect, and SAML v2. The system also provides tools for user management, application theming, and audit logging.

Whether you want to cut software costs or escape vendor lock-in, these open source alternatives to FusionAuth give you an option you fully own. You can self-host them, so your data stays on infrastructure you control. This page lists 1 open source alternative to FusionAuth. The most popular is Zitadel. It uses the AGPL-3.0 license and ships an official Docker image.