Auth0 vs Keycloak: What They Don’t Tell You (and When to Choose One Over the Other)

There’s no shortage of options when it comes to authentication — but let’s be honest: most of us end up Googling “auth for SaaS” and picking either Auth0 or Keycloak.

I’ve worked with both. And depending on where you're at in your product journey, either one could be the right choice — or the wrong one.

Let’s break it down, minus the fluff.

Auth0: Quick, Polished, Expensive

Auth0 is perfect if:

  • You want zero setup
  • You need a hosted solution with docs and UI
  • You’re okay paying a premium for convenience

Auth0 shines for early-stage teams who just want to move fast and not worry about token lifespans or identity providers.

But here’s the catch:

  • You hit pricing walls fast
  • Social logins, RBAC, custom claims = $$$
  • Migrating away is painful
  • Limited flexibility (especially if you need something non-standard)

I’ve seen teams paying $800/month for Auth0 before hitting 10k users.

Keycloak: Free, Powerful, Intimidating

Keycloak is great if:

  • You want full control and zero vendor lock-in
  • You’re building something that needs custom logic, SSO, or integrations
  • You’re okay with getting your hands dirty

Keycloak supports:

  • OIDC, SAML, LDAP
  • Social logins
  • Multi-tenant setups
  • Role-based access
  • User federation
  • Custom login themes

But here’s the reality:

  • The UI is confusing if you’re new
  • Docs are hit-or-miss
  • Theming is ugly out of the box
  • Upgrades can break things
  • Kubernetes deployment takes effort

When to Choose Which

Scenario Use Auth0 Use Keycloak
MVP or early-stage SaaS ✅ ❌
Need it live in 1 day ✅ ❌
Tight budget / no per-user billing ❌ ✅
SAML / LDAP / custom integrations ⚠️ ✅
Don’t want vendor lock-in ❌ ✅
Already using other open-source infra ⚠️ ✅

TL;DR:

Use Auth0 to move fast.

Use Keycloak if you want control, scale, and freedom — but are ready to invest a little time upfront (or get help).

If You’re Going With Keycloak…

I help teams avoid the painful parts.

  • Migrations from Auth0/Okta
  • Clean Keycloak installs (with branding, staging, docs)
  • Setup for social logins, RBAC, SSO, and more
  • Support & handover — no mystery config

Check out 👉 https://pro.keycloakkit.com

Or just DM me if you want to chat about your setup — no pressure at all.