Best Open-Source Auth0 & Okta Alternative in 2026: Keycloak

I run ERPNext and open-source implementations at Mith Tech in Bengaluru, and identity is almost always the second conversation after the first app goes live. The moment a team has ERPNext plus a helpdesk plus a BI tool plus a chat app, nobody wants four separate logins — they want one corporate identity and one password policy. Auth0 and Okta solve that beautifully, but they are proprietary and billed per user, so I get asked for the open-source equivalent constantly. Honest take: Keycloak is not something you set up in an afternoon and forget — it is real infrastructure you have to run — but for a team that wants to own its identity layer and skip per-seat billing, that trade is usually worth it.

What is the best open-source Auth0 alternative in 2026?

Keycloak is the strongest open-source alternative to Auth0 and Okta in 2026. Built as a full identity and access management platform, Keycloak is licensed under Apache 2.0, self-hostable on your own servers, and free to run with unlimited users. Other open-source options exist, but Keycloak is the most mature, most widely deployed and most standards-complete.

The self-hosted identity category has a handful of open-source contenders — Keycloak, Authentik, Authelia, Zitadel and Ory among them. Each has a niche: Authelia leans toward a lightweight reverse-proxy gate, Authentik toward a modern UI, Ory toward API-first developer building blocks. Keycloak is the best general-purpose match for what Auth0 and Okta actually do: centralise authentication, issue tokens, federate existing directories, broker social and enterprise logins, and enforce access policy across many applications at once.

Skimmable summary: Keycloak is the most mature, standards-complete open-source Auth0 and Okta alternative, free to self-host with unlimited users.

What is Keycloak, and how does it work?

Keycloak is an open-source identity and access management server that sits between your users and your applications. Applications delegate login to Keycloak; Keycloak authenticates the user — against its own database, an LDAP directory, or an external identity provider — and returns a signed token the application trusts. One login then unlocks every connected app, which is the essence of single sign-on.

The core building block is the realm — an isolated space that holds its own users, roles, clients and login policies. Inside a realm you register each application as a client using OpenID Connect or SAML 2.0, and Keycloak handles the rest of the flow: login screens, token issuance, refresh, and logout. Because it speaks the open standards directly, most modern apps and frameworks integrate without custom glue. Keycloak also brokers identity, so it can hand off to Google, Microsoft, GitHub or any SAML/OIDC provider and normalise the result into one session.

Keycloak runs on your own infrastructure — a Linux server, Docker or Kubernetes — backed by a relational database such as PostgreSQL. The latest release line, Keycloak 26.7, added step-up authentication to the SAML protocol, letting SAML applications demand stronger authentication for sensitive actions. Because you host it, your user directory, password hashes and tokens never leave infrastructure you control.

Skimmable summary: Keycloak authenticates users and issues standard OIDC/SAML tokens your apps trust, brokering external providers and running on infrastructure you own.

What can Keycloak actually do?

Keycloak covers the identity feature set most SMBs and mid-market teams need, not just basic login. Single sign-on across every connected app is the headline, but the platform also handles multi-factor authentication, passwordless login, directory federation and fine-grained authorization out of the box, without gating the essentials behind an enterprise tier.

The capabilities I lean on most in real deployments:

• Single sign-on and single logout. One login unlocks every connected application; one logout ends the session everywhere.
• Standard protocols. OpenID Connect, OAuth 2.0 and SAML 2.0 are all first-class, so both modern apps and legacy enterprise software integrate.
• User federation. Built-in connectors to LDAP and Active Directory mean existing corporate accounts work without migrating users.
• Identity brokering and social login. Delegate to Google, Microsoft, GitHub or any external SAML/OIDC provider for staff or customer sign-in.
• Multi-factor and passwordless. One-time passwords plus FIDO2/WebAuthn passkeys, with recent releases improving compatibility with passkey managers like iCloud Keychain, Google Password Manager and 1Password.
• Fine-grained authorization. Policy-based access control that goes beyond simple roles when you need it.
• Organizations. Multi-tenant style isolation so different customer groups or business units manage their own users cleanly.

Skimmable summary: Keycloak ships SSO, OIDC/OAuth2/SAML, LDAP/AD federation, social login, MFA, passkeys and fine-grained authorization in the free, open-source core.

Keycloak vs Auth0 vs Okta: how do they compare?

Keycloak, Auth0 and Okta solve the same problem from opposite philosophies. Auth0 (now owned by Okta) and Okta are proprietary, fully managed SaaS platforms with deep polish and broad official SDK coverage. Keycloak is open-source and self-hostable, trading managed convenience for ownership, a free self-hosted model and freedom from per-user billing. All three deliver SSO, OIDC and SAML.

The honest framing: Auth0 and Okta win if you want zero operational burden, the broadest catalogue of drop-in SDKs, and a polished dashboard, and per-user cost is not a concern. Keycloak wins if you want to own the identity layer, keep user data on your own terms, avoid per-seat billing, and are comfortable running the infrastructure. Pricing on the proprietary platforms varies by edition and user count — check each vendor's official page for current figures.

Skimmable summary: Auth0 and Okta lead on managed convenience and SDK breadth; Keycloak leads on open-source ownership, data control and no per-user billing.

Where does Keycloak fall short?

Keycloak has real gaps worth naming before you commit, and almost all of them are operational rather than functional. Auth0 and Okta run the servers, patch the software, scale for you and hand you a support line. With Keycloak, that responsibility is yours — you own the uptime, the upgrades and the incident response.

The specific gaps I flag for teams evaluating the switch:

• You run the infrastructure. A production-ready Keycloak means a database, TLS certificates, high availability, backups and monitoring. That is a genuine DevOps project, not a signup form.
• Upgrades are on you. Keycloak releases frequently. Staying current — and reading release notes for breaking changes — is ongoing work rather than something a vendor absorbs.
• Developer experience is standards-first, not hand-held. The official SDKs are solid and the protocols are open, but Auth0 in particular invests heavily in polished quickstarts across many languages. Expect to lean on standards knowledge rather than a guided path.
• Support is community-first by default. For a vendor SLA, teams often use the Red Hat build of Keycloak, the supported downstream, or a managed-hosting partner. The upstream project itself is community-supported.

None of these is a dealbreaker for most SMB and mid-market use cases, but they are the honest reasons a team that wants zero operational responsibility might still choose a managed platform.

Skimmable summary: Keycloak's gaps are operational — you own hosting, upgrades and support — plus a more standards-first, less hand-held developer experience than Auth0.

Who should choose Keycloak?

Teams that value ownership and want to avoid per-user billing are the best fit for Keycloak. It suits organisations already running open-source infrastructure, businesses with data-residency or on-premise requirements, and teams consolidating many applications behind one corporate identity where a per-seat subscription would scale painfully.

Keycloak is a strong choice when you need to federate an existing Active Directory, when you want SSO across a growing stack of internal and customer-facing apps, or when compliance and data sovereignty mean user data should stay on infrastructure you control. It is a weaker choice if you have no appetite for running infrastructure, need the broadest possible SDK coverage with guided quickstarts, and would rather pay for a fully managed service. For Indian SMBs — where controlling cost and keeping data on your own terms matter, especially under DPDP-era expectations — the open-source model is often exactly the right fit.

Skimmable summary: Keycloak suits ownership-minded teams unifying SSO across many apps; it is a weaker fit for those who want a fully managed, zero-ops identity service.

How does Keycloak fit alongside ERPNext and your other apps?

Keycloak acts as the single identity layer in front of an open-source stack. ERPNext and Frappe apps support SAML 2.0 and OIDC natively, so Keycloak can become the identity provider for Frappe Desk, ERPNext, Frappe CRM and any Frappe app — and the same pattern extends to tools like Grafana, Metabase, Mattermost, Nextcloud and custom apps.

At Mith Tech I treat this as one open-source stack, not a series of separate login decisions. ERPNext is free and open source under GPLv3; Keycloak is free and open source under Apache 2.0. Both self-host, both keep your data on your terms, and both avoid per-seat subscription lock-in. A user logs into Keycloak once and moves between the ERP, the helpdesk, the BI dashboard and the chat tool without re-authenticating, while you enforce one password policy, one MFA rule and one offboarding step across all of them. If you are choosing open-source building blocks generally, our guide to open-source SaaS alternatives maps the wider landscape, our Keycloak page covers how we deploy and integrate it, and our ERPNext page shows the system it most often sits in front of.

Skimmable summary: Keycloak becomes the single identity provider for ERPNext, Frappe and the rest of your stack — one login, one policy, one coherent open-source system.

Frequently asked questions

Is Keycloak really free?

Yes. Keycloak is free and open source under the Apache 2.0 licence, with no licence fees and no per-user pricing. You pay nothing for the software itself; your only costs are the servers you run it on and the engineering time to operate it. For a supported, SLA-backed option, teams can use the Red Hat build of Keycloak — pricing there varies, so check the vendor's official page.

Is Keycloak a genuine open-source Auth0 and Okta alternative?

Yes. Keycloak targets the same job as Auth0 and Okta — centralised authentication, SSO, token issuance and access control across many apps — but is open source and self-hostable rather than proprietary and cloud-only. Auth0 and Okta offer more managed convenience and broader SDKs; Keycloak gives you ownership, data control and no per-user billing.

Does Keycloak support SSO, OIDC and SAML?

Yes. Single sign-on is Keycloak's core function, and it supports OpenID Connect, OAuth 2.0 and SAML 2.0 as first-class protocols. That combination lets it front both modern applications using OIDC and legacy enterprise software that speaks SAML, all from one identity server.

Can Keycloak connect to Active Directory or existing user accounts?

Yes. Keycloak has built-in user federation for LDAP and Active Directory, so existing corporate accounts work without migrating users. It can also broker external identity providers — Google, Microsoft, GitHub or any SAML/OIDC source — for social login and enterprise sign-in.

What is the catch with self-hosting Keycloak?

The catch is operational, not functional. You are responsible for hosting, the database, TLS, high availability, backups, monitoring and upgrades. Keycloak's features are complete and free, but running it in production is a real engineering commitment — which is why many teams either dedicate DevOps time or use a managed-hosting partner.

Can Keycloak integrate with ERPNext and Frappe apps?

Yes. ERPNext and Frappe apps support SAML 2.0 and OIDC natively, so Keycloak can serve as the identity provider for Frappe Desk, ERPNext, Frappe CRM and other Frappe apps. Users then log in once and move across the whole stack, including non-Frappe tools like Grafana, Metabase, Mattermost and Nextcloud, under one identity.