Ory

Keycloak and Ory represent two fundamentally different philosophies in open-source identity. Keycloak is a batteries-included monolith — deploy one service, get everything. Ory is a modular microservices ecosystem — deploy only what you need, build your own UI. This comparison covers architecture, features, authorization, deployment, and when each approach wins. At a Glance Keycloak Ory Architecture Monolith (Java/Quarkus) Microservices (Go) License Apache 2.0 Apache 2.0 GitHub Stars ~25,000 (1 repo) ~39,000 (4 repos combined) Built-in UI Yes (admin + login pages) No (headless, API-first) SAML Support Yes (native) Enterprise only (Ory Polis) LDAP Federation Yes No Authorization UMA 2.0 + policies Zanzibar ReBAC (Keto) Multi-tenancy Realms (production-ready) Enterprise/Ory Network only Managed SaaS No official offering Yes (Ory Network) Min Resources ~512 MB RAM (JVM) ~128 MB RAM per service Architecture Keycloak: The Monolith Keycloak is a single Java application that handles everything: OIDC, SAML, user management, admin console, themes, session management, and authorization services. One deployment, one process, one configuration. ...