FusionAuth
Self-hosted auth from a US team. Lighter than Keycloak, paid for support, free for self-hosting.
VISIT FUSIONAUTHKey takeaway: Between Keycloak's operational weight and the lock-in of hosted SaaS sits FusionAuth: self-host it for free, with a cleaner admin console than Keycloak offers and a documented path to their managed cloud later. The catch is the licence. It is source-available rather than open source, so if OSS purity is a requirement, Authentik is the pick instead.
Quick facts
- CategorySelf-hosted
- LanguageJava
- PricingFreemium
- LicenseProprietary (free self-hosted, paid cloud + support)
- Created2018
- GitHub stars1.4k
- HIPAA-eligibleNo
- SSO / SAMLOut of box
What it is
FusionAuth is a lighter alternative to Keycloak. Self-hostable for free, paid cloud + support tier. Cleaner admin UI than Keycloak, smaller community. Good fit for teams that want self-hosted auth without the JVM-stack heaviness.
Best for
- Self-hosted auth needs without Keycloak's operational footprint
- Teams wanting a polished admin UI
- Apps that may move to cloud later (FusionAuth Cloud is the paid path)
When not to pick it
Skip FusionAuth if you want fully open-source, the codebase is source-available but not OSS-licensed. Skip if Keycloak's ecosystem is the deciding factor.
My take
FusionAuth is the right answer when Keycloak feels too heavy and SaaS feels too lock-in. License model is the trade-off.
Lighter to run than Keycloak, nicer to administer
The practical difference shows up in the first afternoon. FusionAuth deploys as a single Java application against a relational database, so this is still a JVM process, and anyone expecting to escape the JVM entirely should note that before choosing it. What is genuinely lighter is the configuration surface. The admin console is organised the way a product person would organise it rather than the way protocol specifications are organised, and the concepts you have to learn, applications, tenants and users, map onto how you already think about your system. Keycloak's realms and clients get there too, with more reading. The documentation is genuinely good, which matters more than feature checklists when you are debugging a token claim at midnight. It still needs a database, backups, upgrades and monitoring, so this is lighter self-hosting rather than no operations at all.
The licence is the real decision
FusionAuth is not open source. The code is available and self-hosting the community edition is free, but the licence is proprietary, with paid tiers adding advanced features and a hosted cloud with support. For most product teams that distinction is academic: you run it, you do not pay, it works. It stops being academic in three cases. When your legal or procurement process requires an OSI-approved licence. When you want the right to fork if the vendor's direction changes. And when a feature you need turns out to sit behind a paid tier after you have already built on it. Check the feature matrix against your requirements before committing, not after. If any of those apply, Authentik is MIT and Keycloak is Apache 2.0, and both cover similar ground.
Frequently asked questions
Is FusionAuth open source?
No, and the distinction matters more than it first appears. The source is available and the community edition is free to self-host indefinitely, but the licence is proprietary rather than OSI-approved, with some features reserved for paid tiers. If you need a genuinely open-source identity provider, Authentik is MIT and Keycloak is Apache 2.0.
FusionAuth or Keycloak?
FusionAuth when you want self-hosted identity with a cleaner admin experience and a smaller configuration surface, and the licence is acceptable to your legal team. Keycloak when you need deep LDAP and Active Directory federation, the largest enterprise deployments, Red Hat backing, or an Apache-licensed codebase. Both are Java applications that still need a database, backups and upgrade discipline.
Can I move from self-hosted FusionAuth to their cloud?
Yes, that path is designed in and is one of the reasons teams pick it: start self-hosted for free, move to the managed cloud when operating it stops being a good use of your engineering time. Verify first that the features your deployment relies on are available on the tier you plan to move to.
Links
Similar tools you should also consider
If FusionAuth is your pick, the next conversation is short
The 30-min call is where your auth choice becomes a real architecture, a migration plan if you are switching, and a price range you can take to your stakeholders. Describe your stack, your scale, your compliance constraints. I tell you whether FusionAuth is genuinely your fit.