When starting your free and open source multi-factor authentication (MFA) implementation, consider:
- Enterprise-grade MFA solutions: Keycloak, Authelia, Authentik, Zitadel, and Kanidm provide full identity and access management (IAM) with support for multiple authentication protocols.
- Lightweight MFA tools: Hanko, LLDAP, FreeIPA, privacyIDEA, and Rauthy are simpler to configure and better suited to smaller or self-hosted setups.
Features of open source MFA solutions
- Multi-tenancy architecture: Allows multiple independent user groups (tenants) with isolated data and configurations.
- Token impersonation: Allows secure token delegation or impersonation of a user/application for authorized actions.
- Biometric authentication: Offers biometric factors like fingerprints.
- Google Titan Security Key: A hardware-based authentication device that provides phishing-resistant 2FA or passwordless login.
All tools (except LDAP) support hardware tokens (e.g., YubiKey) and the FIDO2 / WebAuthN passwordless authentication protocol. FIDO2 does not use shared secrets, such as passwords; it minimizes the vulnerabilities associated with data breaches.
Enterprise features
- OpenTelemetry: Open-source standard and a set of technologies for capturing and exporting metrics, traces, and logs.
- Custom sessions: Allows fine-grained control over session behaviors, such as:
- How and when MFA is triggered (e.g., at login, for sensitive actions).
- The type of MFA methods supported (e.g., TOTP, WebAuthn, SMS)
- Self-service features:
- Password reset
- User enrollment
Privileged access management (PAM) support
Tools with PAM allow you to manage the access rights of privileged users.
Self-audit capabilities
Self-audit capabilities enhance log traceability, which is critical for MFA (multi-factor authentication) tools. They help track unauthorized or suspicious activity, such as enabling/disabling MFA, failed login attempts, and OTP usage.
Enterprise-grade MFA solutions
Keycloak, Authelia, Authentik, Zitadel, and Kanidm offer extensive MFA capabilities. These free MFA tools offer:
- Several MFA methods: TOTP (time-based one-time password), WebAuthn, SMS, OIDC (OpenID Connect), Email, Push, biometric authentication, and approval-based MFA.
- Several authentication protocols: OAuth2, OIDC (OpenID Connect), SAML, LDAP, and RADIUS.
- Higher customization: Granular RBAC, and custom social SSO connections (OIDC/OAuth2) over MFA policies.
Keycloak
Keycloak is an open-source IAM platform that covers SSO, identity brokering, social login, and RBAC, and supports SAML, OAuth2, OIDC, and LDAP out of the box.
- Keycloak supports multiple database backends, including PostgreSQL, MySQL, MariaDB, Oracle, and Microsoft SQL Server.1
- The administrative workflow automation, JWT Authorization Grants, Kubernetes service account token authentication for clients, and full OpenTelemetry support for metrics and logging. 2
Keycloak is more complex to install and configure than Authelia or Authentik. The default admin UI covers a broad surface area that can be difficult to navigate for teams focused on a narrow set of use cases.
Authelia
Authelia is an open-source authentication and authorization server that provides 2FA and SSO for web applications via a reverse proxy. Rather than acting as a standalone identity platform, it functions as a companion to proxies such as nginx, Traefik, Caddy, and HAProxy, sitting in front of applications and handling authentication decisions. Configuration is managed entirely through a YAML file, which makes it straightforward to version-control and audit but requires familiarity with the configuration schema.
Architecture and resource footprint
The container image is under 20 MB and typically uses under 30 MB of RAM, making it one of the lighter options in this list. Authelia achieved OpenID Connect 1.0 certification and can act as an OIDC provider for downstream applications.3
Recent updates
Version 4.39 added passkeys/passwordless login via WebAuthn, Device Code Flow for TV and shared-screen sign-in scenarios, network criteria for OIDC authorization policies, and RFC8176 Authentication Method Reference support for communicating authentication level to third parties.4
Key features
FIDO2 WebAuthn with hardware keys such as YubiKey, TOTP with compatible authenticator apps, mobile push notifications via Duo, passwordless login via passkeys, policy-based access control, and Kubernetes support via Helm chart.
Limitations
- Authelia has no multi-tenancy, no PAM support, and no built-in user management UI user accounts are managed via LDAP backend or a static YAML file.
- Teams that need a self-service user portal or device management should evaluate Authentik or Kanidm instead.
Authentik
Authentik is a self-hosted IAM platform that covers SSO, LDAP, OAuth2/OpenID Connect, SAML, SCIM, and forward authentication. Compared to Keycloak, it requires less initial configuration for teams without dedicated identity infrastructure experience.
Recent updates
Version 2025.12 added endpoint device management for Windows, macOS, and Linux via the Authentik Agent, WebAuthn Conditional UI, a full RBAC overhaul with multi-parent groups and role-inherited permissions, and centralized file management with S3 support.5
Version 2026.2 added a WS-Federation provider for SharePoint and Windows-native applications, a fleet connector for endpoint device signals and conditional access, Linux PAM support for local device login, and ED25519/ED448 certificate generation.6
Security
Authentik maintains an annual penetration testing program and a formal CVE disclosure process. Three CVEs were published in February 2026, including one critical, patched in versions 2025.8.6, 2025.10.4, and 2025.12.4. Teams running self-hosted instances should maintain updates.7
Limitations
- As of version 2025.10, Redis is no longer requiredAuthentik runs on PostgreSQL only.8
- PostgreSQL remains a hard dependency, which adds operational overhead for single-host personal deployments.
- Authentik also has no native OpenTelemetry support.
ZITADEL
ZITADEL is a self-hosted identity infrastructure platform built around multi-tenancy. It supports OpenID Connect, OAuth2, SAML 2, LDAP, passkeys/FIDO2, OTP, and SCIM 2.0.
Recent updates
ZITADEL completed the migration of core resources instances, organizations, projects, applications, and users to a resource-based API v2.9
- Login V2 reached general availability and became the default for new customers in v4. Actions V2 replaced the embedded V1 extension system with event-driven webhooks that run outside the core process, enabling polyglot support and decoupled scaling.10
- CockroachDB support was removed; PostgreSQL is the only supported database from version 3 onward. 11
Limitations
Administration requires familiarity with ZITADEL’s multi-layer tenant model, which adds setup complexity for single-organization deployments. The 2026 roadmap indicates the team is working on simplifying this model and unifying the management console.12
Kanidm
Kanidm is a self-hosted identity management platform written in Rust.
- Unlike LDAP, which provides only directory services, Kanidm includes native OAuth2, OIDC, RADIUS, SSH key management, and Linux PAM integration without requiring external components.
- Administration is primarily CLI-based; the web UI covers user self-service and some account management, but not full administrative tasks.
Recent updates
The web UI was rewritten in this release, with theming support. Kanidm follows a quarterly release schedule. Upgrades must be performed sequentially through each minor version.13
Limitations
The CLI-first administration model requires comfort with command-line tooling. Kanidm’s own benchmarks with 3,000 users and 1,500 groups report approximately 3x faster search and 5x faster write operations compared to FreeIPA, though results vary by workload.14
Lightweight MFA tools
Hanko, LDAP, FreeIPA, privacyIDEA, and Rauthy cover narrower scopes than full IAM platforms like Keycloak or Authentik. Their protocol support, customization options, and deployment complexity vary significantly, so the category label “lightweight” covers a wide range.
Hanko
Hanko is an open-source authentication service focused on passwordless login. It supports passkeys, TOTP, security keys, OAuth SSO (Apple, Google, GitHub), and custom SAML SSO. It includes server-side session management and remote session revocation.
It does not support custom OIDC/OAuth2 social connections, user impersonation, privileged/step-up sessions, email security notifications, or custom user metadata. Teams requiring those capabilities need a more full-featured platform.
LLDAP
LLDAP is a lightweight LDAP server. It exposes a standard LDAP interface and a web UI for basic user and group management, including password resets by email. It does not provide authentication protocols such as OAuth2 or OIDC, which require a separate component (Keycloak, Authelia, etc.) placed in front of it.
By default, user data is stored in SQLite. MySQL/MariaDB and PostgreSQL are also supported. LLDAP is primarily used in self-hosted environments where applications require LDAP for user lookups, but the operator wants to avoid the operational overhead of OpenLDAP.
privacyIDEA
privacyIDEA is an MFA management system, not a full identity provider. It manages second factors centrally: TOTP, HOTP, OCRA, mOTP, YubiKey (HOTP/TOTP/AES), FIDO U2F, FIDO2/WebAuthn, push tokens, SMS, email, and SSH keys and exposes these via an API that authentication front-ends (Keycloak, FreeIPA, Gluu, NGINX) consume. It does not handle authentication protocols itself.
Recent updates
Version 3.12 added user resolvers for Entra ID and Keycloak, allowing administrators to pull user data directly from those directories and assign tokens in privacyIDEA without a separate sync step.15 This version also introduced a preview of a redesigned web UI; the full UI replacement is planned for version 3.13. Passkey support as a distinct token type was introduced in version 3.11.16
Limitations
- privacyIDEA does not include Kerberos or other authentication protocols natively.
- Automation workflows (enrollment, rollover, onboarding, offboarding) are configurable but require API integration beyond what an out-of-the-box TOTP setup in Keycloak entails.
FreeIPA
FreeIPA is an identity management system for Linux and UNIX environments. It bundles an LDAP directory (389-ds), a Kerberos KDC, a DNS server, a certificate authority, and Samba libraries for Active Directory integration into a single deployable unit with a web UI and a CLI.
It supports TOTP and OTP tokens, as well as FIDO2/passkey authentication. FreeIPA is designed for environments that require centralized Linux host authentication, Kerberos ticket issuance, sudo policy management, and user directory services.
Limitations
- The bundled architecture means deploying FreeIPA involves configuring multiple subsystems.
- Updates and upgrades carry more risk than single-component tools because changes to any bundled service can affect the others.
- It is not a practical choice for environments that do not use Linux/UNIX host-based authentication.
Rauthy
Rauthy is an OpenID Connect provider and single sign-on solution. It supports WebAuthn/FIDO2/passkeys, TOTP, and social login via external identity providers (GitHub, Google, Microsoft, and others configured as generic OIDC upstreams). It is designed for low resource consumption and ships as a single binary or container image.
From version 0.27, Rauthy includes a rauthy-pam-nss module that enables Linux PAM and NSS integration, supporting local workstation logins via YubiKey passkeys and MFA-secured SSH via ephemeral passwords.17
Limitations
Rauthy does not include RADIUS support or a built-in LDAP server. It functions as an OIDC provider that other applications authenticate against; it does not replace a full user directory.
FAQ about MFA
Multi-factor authentication (MFA) requires the user to provide two or more verification factors to access a resource such as an application, online account, or VPN. It is essential to have an effective identity and access management (IAM) policy. Rather than simply requesting a username and password, MFA requires one or more verification factors, reducing the likelihood of a successful cyber attack.
MFA works by requesting additional verification data (factors). One-time passwords are one of the most common MFA factors that users encounter.
OTPs are those 4-8-digit codes that you frequently receive via email, SMS, or a mobile app. OTPs generate a new code regularly or whenever an authentication request is submitted. The code is generated using a seed value assigned to the user when they first register, as well as another factor, which could be anything from an incremented counter to a time value.
Consider your password to be similar to a front door lock. If someone discovers your password, it is as if they have found the key to the lock. Without MFA, they can stroll right in.
However, MFA asks users for extra verification, such as inputting a code sent to their phone or scanning their fingerprint.
This extra step makes it much harder for attackers to break in. Even if a third party obtains one type of authentication (such as your password), they will still need a second or third factor, which is more difficult to acquire.
Further reading
- Top 10 Multi-Factor Authentication (MFA) Solutions
- Top 10 Open Source RBAC Tools Based on GitHub Stars
Reference Links
Cem's work has been cited by leading global publications including Business Insider, Forbes, Washington Post, global firms like Deloitte, HPE and NGOs like World Economic Forum and supranational organizations like European Commission. You can see more reputable companies and resources that referenced AIMultiple.
Throughout his career, Cem served as a tech consultant, tech buyer and tech entrepreneur. He advised enterprises on their technology decisions at McKinsey & Company and Altman Solon for more than a decade. He also published a McKinsey report on digitalization.
He led technology strategy and procurement of a telco while reporting to the CEO. He has also led commercial growth of deep tech company Hypatos that reached a 7 digit annual recurring revenue and a 9 digit valuation from 0 within 2 years. Cem's work in Hypatos was covered by leading technology publications like TechCrunch and Business Insider.
Cem regularly speaks at international technology conferences. He graduated from Bogazici University as a computer engineer and holds an MBA from Columbia Business School.
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