FusionAuth vs Keycloak

The honest comparison

FusionAuth and Keycloak are the two names that dominate the self-hosted identity conversation, but they sit on opposite sides of the open-source line. Keycloak is a fully open-source IAM project (CNCF-adjacent, backed by Red Hat) with no license cost and deep configurability. FusionAuth is a commercial product with a free community edition, flat per-instance pricing, and a more curated developer and operations experience, plus a managed cloud if you would rather not self-host.

When FusionAuth wins

• You want self-hosting without the operational sharp edges of running Keycloak
• Flat, predictable licensing and a managed cloud fallback matter
• First-class multi-tenancy for B2B SaaS is a core requirement
• You value polished APIs, docs, and a faster path from zero to working login

When Keycloak wins

• Zero license cost is a hard requirement and you have the ops capability to run it
• You want a fully open-source platform you can fork, audit, and extend
• Deep protocol configurability and a large community and plugin ecosystem matter
• You are standardizing on Red Hat or a CNCF-aligned stack

Pricing

Keycloak is free and open source; your cost is the infrastructure and the engineering time to operate it. FusionAuth has a free community edition and flat per-instance paid editions, so cost is predictable and does not scale with active users.

Verdict

Choose Keycloak when zero license cost and full open-source control outweigh operational effort. Choose FusionAuth when you want self-hosted ownership with a more polished product, flat pricing, strong multi-tenancy, and a managed option. Both beat per-MAU SaaS economics at scale. Compare against the managed developer-first route in Okta vs Auth0, and see SuperTokens vs FusionAuth for another self-hostable angle.