Zitadel replaces Auth0 and Keycloak for multi-tenant SaaS

Zitadel provides a lower cost for monthly active users than Auth0. A 1,000,000 MAU plan costs $4,500 with Zitadel, while Auth0 charges $9,500 for the same volume. Zitadel uses a Go backend and ships as a single static binary, which avoids the JVM tuning required for Keycloak. You can scale Zitadel horizontally against PostgreSQL without needing the external session cache or Infinispan clustering that Keycloak requires. I find the stateless architecture of Zitadel superior for teams with limited DevOps capacity.

The platform handles B2B requirements through its native multi-tenancy model. Zitadel uses a hierarchy of Instance, Organization, Project, and Application to make each tenant a first-class citizen. This differs from Keycloak, which uses realms to isolate tenants, and Auth0, which manages multi-tenancy via account plans. While Keycloak 26.x added an Organizations feature to help with B2B scenarios, Zitadel’s model integrates these functions into its core design. Each organization in Zitadel maintains its own login policy, identity provider, branding, and user pool.

Compliance and identity management

Zitadel holds SOC 2 Type II and ISO 27001:2022 certifications for its managed cloud. This provides a compliance advantage for B2B SaaS companies that cannot wait a year for a self-hosted stack to pass an audit. Zitadel’s event-sourcing architecture records every state change as an immutable event in the database. This provides a tamper-evident audit trail with zero configuration. Keycloak requires the EventListener SPI and deliberate setup to reach similar levels of audit coverage.

The platform simplifies the migration from US-based providers. Because Zitadel is headquartered in Switzerland, it offers data residency in the EU that avoids CLOUD Act exposure. US-based companies like Okta and Auth0 remain subject to US legal authority regardless of where they host a tenant. I recommend Zitadel to any developer building a modern application that requires OIDC or SAML with EU data residency. Zitadel supports SAML 2.0 as an identity provider, but it cannot consume SAML assertions from upstream sources. Does your team require SAML federation with legacy enterprise systems?

Developer experience and automation

Zitadel follows an API-first design using connectRPC, gRPC, and HTTP/JSON APIs. Every resource and action remains available via these typed APIs. This makes infrastructure-as-code and automation straightforward for engineering teams. Zitadel also uses Actions, which are JavaScript or TypeScript functions executed at runtime lifecycle hooks. These hooks allow for custom logic during pre-auth or post-auth stages without requiring a system rebuild.

The developer experience in Zitadel is more streamlined than Keycloak, though Keycloak has a larger ecosystem of community plugins. Keycloak requires a rebuild to deploy custom SPI extensions as JAR files, whereas Zitadel runs code via serverless hooks. Zitadel’s documentation is clean and its SDKs cover major languages, but its community is smaller than the Keycloak ecosystem. Zitadel’s migration effort is moderate, just like Keycloak’s. I would skip Keycloak if you want to avoid managing a JVM application or a complex cluster.

Zitadel manages identity through a relational core and an event-driven soul. It provides a full audit trail through its event stream, which you can stream to external systems via webhooks. This capability helps teams meet strict regulatory mandates for data provenance. Zitadel provides a pay-as-you-go pricing model for its cloud service. The platform supports OIDC, SAML, SCIM, and WebAuthn. Use Zitadel if you need a lightweight, distributed architecture for a B2B SaaS product.