Keycloak vs Authelia: Self-Hosted Auth Comparison

Last updated: June 2026

Pick Authelia when you want to put SSO and 2FA in front of existing apps behind a reverse proxy with a tiny footprint. Pick Keycloak when you need a full identity provider: an OIDC and SAML server, user management, LDAP federation, identity brokering, and deep extensibility. Both are open source and self-hostable, but they live at different layers of the stack. Authelia is a lightweight proxy companion. Keycloak is a complete IdP.

That distinction matters more than any feature checklist. So before you benchmark RAM usage or count protocols, get clear on which job you actually need done. This guide walks through the architecture, the trade-offs, and the honest “use this one when” guidance for each.

Key Takeaways

• Authelia is a single lightweight Go binary that authenticates and authorizes requests via reverse-proxy forward-auth (nginx, Traefik, Caddy).
• Keycloak is a full OIDC and SAML identity provider with user federation, an admin console, and SPI-based extensibility.
• Authelia added an OpenID Connect Provider feature (still in beta, though OpenID Certified) and has no SAML identity provider, so Keycloak’s protocol breadth and IdP capabilities remain far wider.
• Choose by job: proxy companion (Authelia) versus standalone IdP (Keycloak), not by which one is “better.”

What Problem Does Each Tool Actually Solve?

Keycloak and Authelia are both open source and both self-hostable, yet they answer different questions. Authelia answers “how do I gate my apps behind a login and 2FA using my reverse proxy?” Keycloak answers “how do I run a real identity provider that issues tokens and federates users?” Same neighborhood, different houses.

Here’s the mental model we use. Authelia sits in front of your applications. Your reverse proxy intercepts each request, asks Authelia “is this person allowed?”, and Authelia replies yes or no based on your access-control rules and their authentication state. This is the forward-auth (or auth-request) pattern, and it’s why Authelia is so popular in homelabs and self-hosted stacks. You protect apps that have no real login of their own.

Keycloak works differently. Your applications talk OIDC or SAML directly to Keycloak, redirecting users to log in and receiving signed tokens back. Keycloak owns the user, the session, the protocols, and the trust relationships with external identity providers. It is the source of identity, not a gatekeeper bolted on at the edge.

Citation capsule: Authelia and Keycloak are both open-source, self-hostable authentication tools, but operate at different layers. Authelia provides reverse-proxy forward-auth (an SSO portal plus 2FA in front of apps), per its official documentation. Keycloak is a full OIDC and SAML identity provider with user federation and extensibility, per keycloak.org.

If you do go the IdP route, our guide on running Keycloak behind a reverse proxy covers the setup specifics.

A lot of “Keycloak vs Authelia” debates are really comparing a hammer to a screwdriver. If your apps already speak OIDC or SAML, you usually want an IdP (Keycloak). If your apps speak nothing and you just need a wall with a lock in front of them, you usually want a proxy companion (Authelia). Many serious self-hosters end up running both.

How Do They Compare Head to Head?

The fairest way to compare Keycloak and Authelia is across the dimensions that drive real decisions: architecture, deployment, protocols, MFA, user management, extensibility, footprint, and the use case each was built for. Both are free and open source, so licensing cost is a wash. The interesting differences are structural.

The table below summarizes where each tool fits. Read it as “these solve different jobs,” not “this one beats that one.”

Citation capsule: In a head-to-head, Authelia ships as a lightweight single Go binary designed to add an SSO portal and 2FA via reverse-proxy forward-auth (nginx, Traefik, Caddy), per Authelia’s documentation. Keycloak runs as a Quarkus-based Java application and acts as a full OIDC, OAuth 2.0, and SAML 2.0 provider, per keycloak.org.

Architecture and Deployment

Authelia is built to be small. It ships as a single Go binary (or a compact container) and is designed to run alongside a reverse proxy. That’s its whole personality: minimal moving parts, fast startup, low memory. For a homelab or a lean self-hosted setup, that simplicity is genuinely hard to beat.

Keycloak carries more weight, on purpose. Since version 17 it runs on the Quarkus runtime (not the old WildFly stack), and current releases are on the 26.x line. You run it as a container, through the Keycloak Operator on Kubernetes, or on a VM. It expects an external database (PostgreSQL is the common choice) and uses an embedded caching layer for sessions and clustering. More to operate, but that’s the cost of being a real IdP.

Protocols and Standards

This is where Keycloak’s breadth shows. Keycloak is a full OIDC, OAuth 2.0, and SAML 2.0 provider. Apps integrate by speaking those standards directly to it, and Keycloak issues signed tokens, manages sessions, and brokers logins from external IdPs.

Authelia’s core model is reverse-proxy forward-auth rather than being a protocol server for your apps. It has added an OpenID Connect Provider capability, which lets it act as an OIDC issuer for clients that need it. The implementation is OpenID Certified, though it remains a beta feature that Authelia notes can still see occasional breaking changes. That’s a meaningful addition either way. Authelia does not provide a SAML identity provider at all, so if you need first-class SAML, identity brokering, or the full spread of OAuth 2.0 grant types and extensions, Keycloak is the broader tool. Be honest about what your apps actually require before you assume you need all of it.

In our experience helping teams pick between these, the protocol question usually settles it fast. Teams with a couple of internal dashboards behind nginx almost never need SAML or brokering, and they’re happier with Authelia’s simplicity. Teams onboarding B2B customers, federating with corporate directories, or supporting legacy SAML apps need the IdP, and Keycloak is the answer.

MFA, User Management, and Federation

Both tools take multi-factor seriously. Authelia supports TOTP, WebAuthn, and push-style mobile second factors, which covers most self-hosting needs cleanly. Keycloak supports TOTP, WebAuthn and passkeys, recovery codes, and step-up authentication driven by configurable authentication flows, which is more granular when you need conditional or risk-based prompts.

The bigger gap is user management and federation. Keycloak gives you a full admin console, a self-service account console for end users, and LDAP/Active Directory federation plus identity brokering from external providers. Authelia keeps users lightweight: defined in a file or backed by an LDAP directory, with no rich admin UI for managing accounts. If you need to administer many users, federate a corporate directory, or broker logins, that’s squarely Keycloak territory. If you’re weighing other full IdPs in the same breath, our Keycloak vs FusionAuth comparison digs into another popular option.

Extensibility and Footprint

Footprint is Authelia’s home-field advantage. One Go binary, low memory, fast to deploy, easy to reason about. Keycloak’s JVM-plus-database-plus-cache stack uses more resources, which is the trade you make for an enterprise-grade IdP. Neither is wrong; they’re sized for different jobs.

Extensibility flips the script. Keycloak exposes Service Provider Interfaces (SPIs) so you can write custom authentication flows, custom user storage, protocol mappers, event listeners, and more, then drop them in as deployable providers. Authelia is configuration-driven rather than a plugin platform, which keeps it simple but limits how far you can bend it. If you need to deeply customize identity behavior, Keycloak’s SPI model is in a different class.

When Should You Choose Authelia?

Choose Authelia when your goal is to put SSO and 2FA in front of apps that don’t have proper login of their own, behind a reverse proxy, with the smallest possible footprint. It’s a favorite in homelabs and self-hosted stacks for exactly this reason: a single Go binary protecting a fleet of services behind nginx, Traefik, or Caddy.

Reach for Authelia when:

• You run a reverse proxy already (nginx, Traefik, Caddy) and want forward-auth gating.
• You need an SSO portal plus 2FA in front of apps, not a standalone token issuer for them.
• Footprint and operational simplicity are top priorities (homelab, small team, lean VPS).
• Your user list is small and a file-based or LDAP backend is plenty.
• You don’t need SAML, identity brokering, or heavy customization.

Citation capsule: Authelia is commonly chosen by self-hosters and homelab users to add an SSO portal and multi-factor authentication in front of applications via reverse-proxy forward-auth, per Authelia’s documentation. It runs as a single lightweight Go binary, making it well suited to resource-constrained, proxy-centric deployments.

Credit where it’s due: for the proxy-companion case, Authelia is the cleaner, lighter, faster-to-stand-up choice. Don’t reach for a full IdP just because it has more features you won’t use.

When Should You Choose Keycloak?

Choose Keycloak when you need a real identity provider: a standalone OIDC and SAML server that owns users, issues tokens, federates directories, and can be customized deeply. Keycloak is open source under Apache 2.0, is a CNCF project, and is the standard self-hosted IdP for teams whose apps speak OIDC or SAML directly.

Reach for Keycloak when:

• Your apps integrate via OIDC or SAML and need a true token-issuing provider.
• You need user management at scale: an admin console, self-service, and full user CRUD.
• You require LDAP/Active Directory federation or identity brokering from external IdPs.
• You need step-up authentication, custom authentication flows, or SPI-based extensions.
• You’re building B2B SSO, customer portals, or workforce IAM rather than just gating internal tools.

Citation capsule: Keycloak is an open-source identity and access management provider, licensed under Apache 2.0 and hosted by the CNCF, offering OIDC, OAuth 2.0, and SAML 2.0 alongside user federation and SPI-based extensibility, per keycloak.org. It targets standalone IdP use cases rather than reverse-proxy gating.

The honest caveat: Keycloak asks more of you operationally. You run a JVM app, a database, and a caching layer, and you own upgrades, tuning, and high availability. That’s the price of a full IdP, and it’s a real cost. If you want the IdP without the ops burden, that’s exactly the gap managed hosting fills.

Can You Run Both Together?

Yes, and plenty of self-hosters do. Authelia can sit at the reverse-proxy edge handling forward-auth for apps with no native login, while Keycloak serves as the central IdP for apps that speak OIDC or SAML. Authelia can even delegate authentication to an upstream OIDC provider, so the two can complement rather than compete.

A common pattern looks like this. Keycloak is the identity source of record, holding users and federating your directory. Apps that support OIDC or SAML integrate with Keycloak directly. Legacy or off-the-shelf apps that have no real auth get parked behind the proxy, and Authelia gates them, optionally trusting Keycloak as the upstream login. You get IdP power where you need it and lightweight gating everywhere else.

The “versus” framing sells the rivalry harder than reality does. In mature self-hosted environments, the most pragmatic setup is often “Keycloak as the brain, Authelia as the bouncer.” Deciding which one to run isn’t always either/or; sometimes the right answer is both, each doing the job it’s good at.

Frequently Asked Questions

Is Authelia a replacement for Keycloak?

Not really, for most use cases. Authelia is a lightweight reverse-proxy authentication companion (SSO portal plus 2FA via forward-auth), while Keycloak is a full OIDC and SAML identity provider with user federation and extensibility. Authelia added a beta OpenID Connect Provider feature and has no SAML provider, so it doesn’t match Keycloak’s protocol breadth, brokering, or admin capabilities.

Does Authelia support OIDC and SAML like Keycloak?

Partly. Authelia has added a beta OpenID Connect Provider capability, so it can act as an OIDC issuer for clients that need it. It does not provide SAML at all. Keycloak, by contrast, is a full provider for OIDC, OAuth 2.0, and SAML 2.0, plus identity brokering. If you need first-class SAML or directory federation, Keycloak is the broader, purpose-built tool for that job.

Which is more lightweight, Keycloak or Authelia?

Authelia, clearly. It ships as a single Go binary with a small memory footprint, designed for proxy-centric and homelab setups. Keycloak runs as a Quarkus-based Java application that expects an external database and a caching layer, so it uses more resources. That heavier footprint is the trade-off for being a full identity provider rather than an edge gatekeeper.

Can I use Authelia and Keycloak together?

Yes. Authelia can gate apps at the reverse-proxy edge using forward-auth while Keycloak acts as the central OIDC and SAML identity provider for apps that speak those protocols. Authelia can also delegate authentication to an upstream OIDC provider, so the two complement each other. Many self-hosters run “Keycloak as the brain, Authelia as the bouncer.”

Are both Keycloak and Authelia free and open source?

Yes. Keycloak is open source under the Apache 2.0 license and is a CNCF project, with every feature available at no license cost. Authelia is also open source and free to self-host. With both, your real costs are infrastructure and operational effort, or a managed hosting fee if you’d rather not run the IdP yourself.

Summary

Keycloak and Authelia are both open source and self-hostable, but they solve different problems. Authelia is a lightweight Go binary that gates apps behind a reverse proxy with an SSO portal and 2FA, ideal for homelabs and lean setups. Keycloak is a full OIDC and SAML identity provider with user federation, an admin console, and SPI-based extensibility, built for standalone IdP use cases.

Decide by the job, not the feature count. Need a wall with a lock in front of existing apps behind a proxy? Authelia wins on simplicity and footprint. Need a real token-issuing IdP with federation, brokering, and deep customization? Keycloak wins on protocol breadth and capability. And if you’re running serious infrastructure, “both” is a perfectly valid answer.

Run Keycloak Without the Ops Burden

Keycloak’s biggest downside isn’t features, it’s operations. You own the JVM app, the database, the caching layer, upgrades, tuning, and high availability. That’s real work, and it’s exactly why teams stall on adopting a full IdP.

Skycloak runs managed Keycloak hosting so you get the identity provider without babysitting the infrastructure. We handle deployment, upgrades, scaling, and the boring-but-critical reliability work, while you keep full Keycloak with its open-source feature set and extensibility. Want the IdP power without the ops tax? See Skycloak managed Keycloak hosting.