Proprietary vs Open source
Clerk vs Keycloak: Which One Should You Choose in 1970?
Clerk is a proprietary Authentication & User Management tool priced as mAU-based Freemium, starting at $25/mo. Keycloak is open source, priced as 100% Free Open-Source (Red Hat Community), starting at $0 (Free Self-Hosted).
Quick verdict
- Choose Clerk for
- Clerkworld-class Next.js / React UI components (`<SignIn />`, `<UserProfile />`)
- Choose Keycloak for
- Keycloakcomplete enterprise SSO, LDAP/Active Directory sync, Kerberos, OpenID Connect
Clerk vs Keycloak: feature comparison
| Feature | ClerkProprietary | KeycloakOpen SourceSelf-Hostable |
|---|---|---|
| Open-Source Available | No | Yes |
| Self-Hostable | No | Yes |
| Self-Hosting Difficulty | N/A | High (Java/Quarkus container, DB setup) |
| Pricing Model | MAU-based Freemium | 100% Free Open-Source (Red Hat Community) |
| Starting Price | $25/mo | $0 (Free Self-Hosted) |
| Free Tier | Free up to 10,000 monthly active users | Unlimited users, unlimited realms, 100% free |
| GitHub Stars | N/A | 24k |
Pricing takeaway
Clerk starts at $25/mo (free up to 10,000 monthly active users). Keycloak starts at $0 (Free Self-Hosted) (unlimited users, unlimited realms, 100% free).
- Clerk
- MAU-based Freemium. Starts at $25/mo. Free up to 10,000 monthly active users.Full Clerk pricing breakdown
- Keycloak
- 100% Free Open-Source (Red Hat Community). Starts at $0 (Free Self-Hosted). Unlimited users, unlimited realms, 100% free.Full Keycloak pricing breakdown
Pros and cons
Clerk
Visit ClerkPros
- World-class Next.js / React UI components (`<SignIn />`, `<UserProfile />`)
- Flawless multi-session and Passkey / WebAuthn support
- 10-minute developer onboarding with pre-styled widgets
Cons
- Closed source; tightly coupled to modern React/frontend stacks
- Self-hosting is not available
- Pricing is tied to MAU, so products with many dormant sign-ins keep paying for users who never return
Keycloak
Visit KeycloakPros
- Complete enterprise SSO, LDAP/Active Directory sync, Kerberos, OpenID Connect
- Multi-tenancy realms out of the box with zero user license fees
- No vendor lock-in; ideal for on-premise and sensitive regulated data
Cons
- High DevOps maintenance burden and Java memory footprint
- Default login UI is dated and requires custom theme development
- Major-version upgrades regularly need migration work on custom themes and providers
Clerk vs Keycloak: FAQ
Is Keycloak a good alternative to Clerk?
Clerk is a proprietary Authentication & User Management tool priced as mAU-based Freemium, starting at $25/mo. Keycloak is open source, priced as 100% Free Open-Source (Red Hat Community), starting at $0 (Free Self-Hosted).
Which is cheaper, Clerk or Keycloak?
Clerk starts at $25/mo (free up to 10,000 monthly active users). Keycloak starts at $0 (Free Self-Hosted) (unlimited users, unlimited realms, 100% free).
Is Clerk or Keycloak open source?
Clerk is proprietary. Keycloak is open source (github.com/keycloak/keycloak).
Can I self-host Clerk or Keycloak?
Clerk cannot be self-hosted. Keycloak can be self-hosted. Difficulty: High (Java/Quarkus container, DB setup).
Do Clerk and Keycloak have a free tier?
Clerk: Free up to 10,000 monthly active users. Keycloak: Unlimited users, unlimited realms, 100% free.