Keycloak vs Auth0: The Self-Hosted Alternative, Compared

Most teams don’t leave Auth0 because it’s bad. They leave because the bill stops making sense.

Auth0 is a genuinely good product — fast to integrate, well-documented, and it removes an entire category of work. But its pricing scales with monthly active users, and two things happen as you grow: the number goes up with your success, and the features you actually need in production sit behind a tier jump. One company reported its bill rising 15.5× after user growth of just 1.67×. Others have paid $34,000+ a year for little more than SAML.

That’s the moment people start Googling “self-hosted Auth0 alternative.” The answer, almost always, is Keycloak. Here’s the honest comparison.

What each one actually is

Auth0 (owned by Okta since a $6.5B acquisition) is a hosted CIAM platform. You call their API, they run everything. Zero operational burden, and you pay per monthly active user.

Keycloak is the open-source standard for identity and access management. It’s a CNCF project, battle-tested in large enterprises, and speaks the same protocols Auth0 does — OIDC, SAML 2.0, OAuth 2.0 — plus MFA and passwordless (FIDO2/WebAuthn). The difference: you run it (or someone runs it for you), and there’s no per-user fee.

Functionally, for the vast majority of use cases, they do the same job. The real decision is about cost model, control, and who operates it.

Feature comparison

The pattern is clear: Keycloak matches Auth0 on capability, wins on cost model and sovereignty, and loses on one thing — you have to operate it. That single tradeoff is the whole story, so let’s be honest about both sides of it.

Where Auth0 actually hurts

Four specific things push teams off Auth0, and none of them is “the product is bad”:

1.        MAU pricing is a growth penalty. You’re billed for the users who make you successful. Budgeting is hard because the number moves with adoption, and overages run $0.07/MAU. For a growing B2B or consumer product, the identity line becomes a meaningful, unpredictable cost.

2.        The features you need live behind a tier jump. Need SAML for an enterprise customer? On B2B that means the Professional plan — roughly $800/month for 1,000 MAU, versus $150 on Essentials. The jump is about the feature gate, not your usage.

3.        Your identity data sits in a US-controlled platform. For a European company under GDPR — or in scope for NIS2 — you don’t control where the user store lives or how it’s audited. You’re renting compliance rather than holding it.

4.        Getting out is deliberately hard. This is the one that surprises people most. With Keycloak you own the database — export the entire realm (users, roles, clients, even credentials) and stand it up on another provider in an afternoon. With Auth0, exporting your users is a support-gated process, password hashes aren’t part of a normal self-serve export, and the longer you stay the more custom rules and flows you have to unpick. The exit cost is real, and it grows every month you don’t move. Portability isn’t a footnote — it’s the whole point of owning your identity layer.

The honest catch with Keycloak

Keycloak isn’t free in the way people hope. The software is free; running it in production is not trivial. You’re responsible for:

•          High-availability deployment (usually on Kubernetes), upgrades, and database operations

•          Security patching — identity is the highest-value target on your network

•          MFA/passwordless policy, realm design, and integration work

•          Monitoring, backups, and being on call when logins break at 2 a.m.

For a team with strong platform engineering, that’s a fair trade for open source and no per-user fees. For most teams, it’s exactly the work they went to Auth0 to avoid. Which is the real point: the choice isn’t “Auth0 vs. Keycloak.” It’s “who operates your identity layer.”

The middle path: managed Keycloak

There’s a third option that most “vs” articles skip: run Keycloak, but have someone else operate it. You get Keycloak’s open standards, no per-MAU pricing, and full data control — without taking on the ops burden that sent you looking in the first place.

That’s what we do. We run Keycloak for you in our Frankfurt data center — 24/7 operations, immediate security patches, MFA/passwordless policy, backups and an SLA — and your identity data stays in Germany. To make that repeatable, we build and maintain an open-source Keycloak Operator for Kubernetes that does declarative, GitOps-driven Keycloak the same way every time. It’s the difference between “we installed Keycloak once” and “we operate Keycloak as a product.”

If you want the full picture of the managed offering, it’s here: Managed Keycloak (Auth0 Exit).

When Auth0 is genuinely the right call

We’re not here to talk you off a product that fits. Stay on Auth0 if:

•          You’re small and staying small — under a few thousand MAU, the bill is negligible and the zero-ops convenience is worth it.

•          You have no platform engineering capacity and no appetite for managed operations either — Auth0’s fully-hosted model is the lowest-effort path.

•          You need a specific Auth0-only feature or deep integration you can’t easily reproduce.

•          Cost and data location simply aren’t concerns for your business.

The math flips when the identity bill becomes significant, when SAML/enterprise features force a tier jump, or when GDPR/NIS2 makes data location a real requirement — which, for European B2B, it usually does.

Frequently Asked Questions

Is Keycloak a real alternative to Auth0?
Yes. Keycloak implements the same standards — OIDC, SAML 2.0, OAuth 2.0 — plus MFA and passwordless (FIDO2/WebAuthn), and it’s used in production by large organizations. The functional gap for most use cases is small; the difference is the cost model and who operates it.

Is Keycloak cheaper than Auth0?
The software is free and has no per-user fee, so at scale it’s dramatically cheaper than Auth0’s MAU pricing. But “free software” isn’t “free” — you pay in operations, or you pay someone to run it (still far less than per-MAU billing at scale).

Can I migrate from Auth0 or Okta to Keycloak without downtime?
Yes. Keycloak runs in parallel with your existing provider; you connect apps and directories, then cut over app by app with the old provider as a fallback. Most migrations are staged with no user-facing downtime.

Does Keycloak support SAML and passwordless like Auth0?
Yes — SAML 2.0 and OIDC are core, and FIDO2/WebAuthn passwordless plus TOTP MFA are built in. Unlike Auth0, SAML isn’t gated behind a higher pricing tier.

Do I have to run Keycloak myself?
No. You can self-host it, or use a managed provider that operates it for you — you keep the open standards and data control without the operational burden.

Thinking about leaving Auth0?

Talk to an engineer — 30 minutes, no sales pitch. Tell us your setup and we’ll tell you honestly whether Keycloak is worth the switch, and what the migration would take.