FusionAuth vs Ory Kratos
A side-by-side comparison of two self-hosted identity & sso options — licensing, setup difficulty, resource needs, and what each one replaces.
FusionAuth
Complete authentication and authorization platform
VS
Ory Kratos
Headless identity and user management API server
| Feature | FusionAuth | Ory Kratos |
|---|---|---|
| Deploy effort | Under-an-hour setup | Under-an-hour setup |
| Health score | 70 · Good | 89 · Excellent |
| Category | Identity & SSO | Identity & SSO |
| License | Apache-2.0 | Apache-2.0 |
| Language | Dockerfile | Go |
| Setup difficulty | Medium | Hard |
| Min. RAM | 1,024 MB | 256 MB |
| Deployment | docker, kubernetes, bare-metal | docker, kubernetes, binary |
| GitHub stars | ★ 241 | ★ 13,888 |
| First released | 2018 | 2020 |
| Replaces | Auth0, Okta | Auth0, Firebase Auth |
What are FusionAuth and Ory Kratos?
FusionAuth
FusionAuth is a self-hostable customer identity and access management platform supporting OAuth, OIDC, SAML, MFA, and user management. The community edition runs free on your own infrastructure.
- OAuth, OIDC and SAML support
- Multi-factor authentication
- User and tenant management
- Themable login pages
Ory Kratos
Ory Kratos is an API-first identity and user management system. It handles login, registration, profile management, account recovery and multi-factor authentication without prescribing a user interface.
- Headless API for full UI control
- Self-service flows for login and recovery
- Pluggable MFA including TOTP and WebAuthn
- Cloud-native and stateless design
FusionAuth vs Ory Kratos: key differences
FusionAuth is written in Dockerfile, while Ory Kratos is built with Go. Ory Kratos is the lighter option, starting around 256 MB of RAM against 1,024 MB for FusionAuth. FusionAuth is the more established project (first released 2018), while Ory Kratos arrived in 2020. Ory Kratos has the considerably larger community, at 13,888 GitHub stars versus 241.
Why pick each one
Choose FusionAuth if…
- Released under the Apache-2.0 license
- First-class Docker support for quick deployment
- Kubernetes-ready with Helm charts available
- Written in Dockerfile
Choose Ory Kratos if…
- Extremely flexible architecture
- Excellent for custom frontends
Watch out for
- Requires building your own UI
- Complex initial setup
Frequently asked questions
Is FusionAuth or Ory Kratos better?
Neither is universally better. Ory Kratos has the larger community, while FusionAuth is simpler to set up (medium difficulty). Choose based on the comparison table above and your own setup.
Are FusionAuth and Ory Kratos free and open-source?
Yes. FusionAuth is licensed under Apache-2.0 and Ory Kratos under Apache-2.0. Both can be self-hosted at no software cost.
Can I run FusionAuth and Ory Kratos with Docker?
FusionAuth: yes. Ory Kratos: yes.
Which is lighter on resources, FusionAuth or Ory Kratos?
Ory Kratos has the smaller minimum footprint at 256 MB of RAM, compared to about 1,024 MB for FusionAuth. Real-world usage depends on library size, user count, and enabled features.