Zitadel

Zitadel is an identity infrastructure platform for developers: authentication and access management for applications, built API-first and multi-tenant rather than added on as a login screen. Teams use it to run sign-in for consumers, business customers or employees without building an identity stack in-house. A hosted, brandable login page comes out of the box, and the same functions are exposed through APIs. Backends, IoT devices and CLIs authenticate against the same platform as machine identities.

Single sign-on runs over OpenID Connect, SAML and OAuth 2.0, with brokering to social, government and enterprise providers such as Keycloak, Auth0 and Azure AD. Multifactor options include OTP, U2F and passkeys, with passwordless WebAuthn at no extra charge. Multi-tenancy is core: organizations are created and granted projects, and management of selected roles can be delegated to customer organizations. An append-only event store keeps an unlimited audit trail, and Actions run custom code on events. The company reports 10,000+ GitHub stars, 250+ contributors, 160+ customers and users in 69 countries. It runs as Zitadel Cloud, with EU, US, Swiss and Australian data residency, or self-hosted; the free tier covers unlimited users and organizations at 100 daily active users.

Zitadel was founded in 2019 in Switzerland by a group then working at a public sector company there, and it treats identity as foundational infrastructure that should be open and community-driven. The code is open source and self-hostable, including air-gapped or regulated environments; it launched under Apache 2.0 and later moved to AGPL 3.0. ZITADEL Inc. in San Francisco is the parent company; CAOS AG in Switzerland holds cloud and non-US enterprise contracts under Swiss law.