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IAM
SSO providers

Top 5 Open Source Identity and Access Management (IAM) providers 2025

Compare features, protocols, integrations, pros, and cons for Logto, Keycloak, NextAuth, Casdoor, and SuperTokens to find the best OSS fit for your authentication and authorization needs.

Ran

Product & Design

3/12/20259 min read

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What is an IAM provider?

An Identity and Access Management (IAM) provider is a system that ensures secure, controlled access to resources. It combines four pillars:

Authentication: Verifying user identities (e.g., passwords, biometrics, social login).
Authorization: Granting permissions based on roles or policies.
User Management: Handling provisioning, roles, and audits.
Organization Management: Structuring teams, permissions, and multi-tenancy. IAM tools are essential for enforcing security policies, preventing breaches, and meeting compliance standards like SOC 2, GDPR, and HIPAA.

Key considerations for choosing an open-source IAM solution

Here are the core requirements:

Integration-ready SDKs & deployment flexibility: Ensure compatibility with your tech stack (e.g., languages, frameworks, databases), and provide popular deployment options (e.g., npm packages, Docker containers, GitPod integration, or one-click hosting). This help reduce setup time and accelerates time-to-market.
Protocol support for interoperability: Must support OAuth 2.0, OpenID Connect (OIDC), SAML, and LDAP for integration with third-party apps and identity providers (Google, Apple, Azure AD, etc.). Open standards minimize vendor lock-in and simplify federated identity workflows.
Business-ready feature modularity: Choose a solution that offers modular components to address current needs while scaling for future demands:
- Authentication: Password, Passwordless, social login, SSO, biometrics, and M2M auth.
- Authorization: RBAC, ABAC, and API protection.
- Management: User lifecycle tools, audit logs, webhooks, and compliance reporting.
- Security: MFA, encryption, password policy, brute-force protection, bot detection, and blocklist. Choose project with transparent security practices (SOC2 / GDPR compliance).
User experience (UX) optimization : Prioritize solutions with prebuilt auth flows (login, registration, password reset) to reduce development effort. Ensure end-user flows are intuitive, mobile-friendly, and customizable to boost conversion rates.
Customization & extensibility: APIs and webhooks should allow tailoring auth workflows, UI themes, and policy logic to match unique business rules. Avoid "black box" solutions—opt for transparent, community-driven code.

Here are some differentiators for long-term success:

Developer experience (DX): Comprehensive documentation, code samples, and sandbox environments (e.g., Postman collections, CLI tools), and low-code admin consoles streamline setup and reduce errors.
Community & enterprise support: Thriving community (Discord, GitHub) for troubleshooting and knowledge sharing. Enterprise support options (SLAs, dedicated engineering) provide reliability for mission-critical deployment.
Scalability: Regular updates for zero-day vulnerabilities and emerging standards (e.g., FIDO2). Hybrid deployment options (OSS + Cloud) simplify scaling and reduce operational overhead.

These seem a little harsh for open source projects, but there are already services that can meet, let's take a look.

The top 5 open-source IAM providers

Logto: Developer-first IAM with authentication, authorization, user management, and mutli-tenancy — all in one. It’s framework-free, OIDC/OAuth/SAML supported, and totally free OSS.
Keycloak: An enterprise-grade protocol powerhouse (SAML/OAuth/LDAP) designed for organizations that need fine-grained access control and self-hosting.
NextAuth: A lightweight authentication library tailored for Next.js developers, simplifying social logins, passwordless authentication, and session management.
Casdoor: A UI-first IAM and Single Sign-On (SSO) platform with a web UI, supporting OAuth 2.0, OIDC, SAML, CAS, LDAP, and SCIM.
SuperTokens: An OAuth 2.0-based authentication solution, open-source flexibility, and commercial scalability.

#1 Logto

Logto is an open-source Auth0, Cognito and Firebase auth alternative for modern apps and SaaS products, supporting OIDC, OAuth 2.0 and SAML open standards for authentication and authorization.

Home page | GitHub Repo | Documentation | Discord community

Key features of Logto OSS

Protocols: OIDC, OAuth 2.0, SAML 2.0
Official SDKs:
- Official SDKs: Android, Angular, Capacitor JS, Chrome Extensions, .NET Core, Expo, Express, Flutter, FlutterFlow, Go, Java Spring Boot, Next.js (both Page and App Router), Auth.js (NextAuth), Nuxt, Passport.js, PHP, Python, React, Ruby, SvelteKit, iOS, Vanilla JS, Vue, Webflow, WordPress, Hasura, and Supabase.
- Custom integration: Traditional web apps, SPAs, mobile apps, M2M, OAuth apps, and SAML apps.
Authentication methods: Password, email and SMS passwordless, social logins, enterprise SSO, MFA with authenticator TOTP / passkeys / backup codes, personal access tokens, Google One Tap, invitation, account linking, and OAuth consent flows.
Authorization: API protection, RBAC for users/M2M, organization‑level RBAC, JWT/opaque token validation, and custom token claims.
Multi‑tenancy: Organization templates, member invitations, per‑organization MFA, just‑in‑time provisioning (JIT), and tailored sign‑in experiences for each tenant.
User Management: User impersonation, user creation and invitations, suspend users, audit logging, and user migration.
User experience: Provides beautiful, out‑of‑the‑box, fully customizable authentication flows, enabling a unified multi‑app omni‑login experience through federated identity management.
Provider integration:
- Social Providers: Google, Facebook, Microsoft, Apple, GitHub, X.com, LinkedIn, Slack, Amazon, Discord, Line, WeChat, Kakao, etc. Fully customizable via OpenID Connect or OAuth 2.0.
- Enterprise Providers: Microsoft Azure AD, Google Workspace, Okta, etc. Fully customizable via OpenID Connect or SAML.
- Email delivery providers: AWS, Mailgun, Postmark, SendGrid, etc. configurable via SMTP or HTTP call.
- SMS delivery providers: Twillio, SMS Aero, GatewayAPI, Vonage, Aliyun, and Tencent.

Pros of Logto OSS

100% Free OSS: All core features (including SSO, RBAC, Organizations, etc.) available for free; no paywalled essentials.
Enterprise‑grade security: SOC2-ready architecture, MFA, SSO, API protection, multi‑tenant isolation, brute-force protection, and audit logs.
Be an identity provider: With Logto, you can turn your service into an identity provider, enabling seamless integration across multiple applications, platforms, and device. Support OIDC, OAuth 2.0, and SAML 2.0 for universal single sign-on and federated identity management.
External ecosystem integration for partnership: Logto supports M2M authentication, personal access tokens, user impersonation (token exchange), OAuth authorization for third-party apps with a consent screen, and customizable connection for third-party identity providers, all fuel your product growth.
Developer‑friendly: Well‑structured APIs, SDKs, Docs, and intuitive console.
Scalable deployment: Logto is available as a free OSS, while Logto Cloud offers managed services with assured updates and financial backing for long‑term support.
Active community: A responsive Discord community and proactive core team ensure timely issue resolution and continuous feature enhancements.
Lightweight & Modern: Built with modern design principles, optimized for speed and efficiency, suitable for individual developers, startups, and enterprises.

Cons of Logto OSS

Redirect‑based authentication: Based on OIDC, requiring redirection to the identity provider, which may not fit scenarios that demand a non‑redirect experience. However, Logto offers embedded direct sign-in components (Social, SSO, etc.) to work around this.
Limited B2E features: Not built-in LDAP/Active Directory sync and ultra‑granular authorization yet.
Growing Ecosystem: Smaller community compared to older solutions, but rapidly evolving with contributions.

#2 Keycloak

Keycloak is a enterprise-ready IAM solution with robust support for SAML, OAuth, and LDAP, ideal for organizations prioritizing protocol flexibility, self-hosting, and fine-grained access control.

Home page | GitHub Repo | Documentation | Slack community

Features of Keycloak

Protocols: OIDC, OAuth 2.0, SAML 2.0, LDAP
Official SDKs: Java, JavaScript, Node.js, C#, Python, Android, iOS, Apache HTTP Server
Authentication methods: Single Sign-On (SSO), Multi-Factor Authentication (MFA), Social login, Kerberos.
User experience: Out-of-the-box sign-in interfaces and account management console with customizable HTML, CSS, and Javascript.
Fine-Grained Authorization: access control based on roles, attributes, or other criteria.
Directory sync: Synchronize from existing enterprise directories (LDAP/Active Directory).
Pluggable architecture: Custom extensions and integrations.

Pros of Keycloak

Comprehensive features set for enterprises: Such as SSO, MFA, identity brokering, user federation, and support for multiple protocols (OAuth 2.0, OpenID Connect, SAML).
Customizable user interface & admin management settings: Provides a default login UI and administrative console that can be themed and extended.
Integration & extensibility: Easily integrates with external identity providers (like LDAP/AD and social logins) and supports custom extensions via plugins.
Active community & ongoing development: Regular updates, active community support, and backing by Red Hat ensure continuous improvement and security patches.

Cons of Keycloak

Steep learning curve: Setting up realms, clients, and authentication flows can be tricky, especially for teams without deep IAM experience.
Customization challenges: While flexible, tweaking the UI often requires working with FreeMarker templates or custom SPIs, which can be tedious.
High maintenance: Frequent major updates and breaking changes make upgrades tricky, requiring careful coordination between server and client libraries.
Resource-heavy: Running Keycloak in high-availability or containerized setups can demand significant CPU/RAM and careful performance tuning.
Documentation gaps: While basics are well covered, advanced features and edge cases often lack detailed or up-to-date documentation.

#3 Auth.js/NextAuth.js

NextAuth.js is a lightweight authentication library designed for Next.js, offering a simple setup for social logins, passwordless authentication, and session management with minimal configuration.

Home page | GitHub Repo | Documentation | Discord community

Features of NextAuth.js

Protocols: OAuth 2.0, OIDC
Frameworks: Next.js, Node.js, and serverless platform (e.g., Vercel, AWS Lambda)
Authentication methods: Social login, Magic links, Credientials, WebAuthn (Passkey).
Authentication experience: Default sign‑in, sign‑out, error, and verification pages; and can override them to create a fully branded and tailored user experience.
Session management: Support for both JSON Web Token (JWT)–based stateless sessions and database-backed sessions.

Pros of NextAuth.js

Seamless Next.js integration: Designed specifically for Next.js, it works smoothly with server-side rendering (SSR), static site generation (SSG), and API routes. Developers can easily manage authentication state using hooks like useSession and components like SessionProvider.
Customizable authentication flow: Built-in callbacks for sign-in, JWT handling, and session management allow deep customization, giving developers full control over authentication behavior and token processing.
Active community and ecosystem: A strong developer community contributes tutorials, examples, and discussions, making it easier to troubleshoot issues and extend functionality.

Cons of NextAuth.js

Limited IAM features: Lack SMAL, SSO, MFA, multi-tenancy, and other key authentication features for B2B or B2E use cases. It focus purely on authentication, with no built-in support for authorization or user management.
Inconsistent and poor documentation: Many users report that documentation is scattered, outdated, and difficult to follow, especially when upgrading to new versions or transitioning to the app directory structure.
Stability and bug concerns: Developers have encountered session handling issues, refresh token bugs, and unpredictable behavior, sometimes requiring workarounds or alternative solutions.
Steep learning curve: The API and configuration can feel complex, especially for beginners. Frequent breaking changes—such as those introduced in NextAuth.js v5 beta—increase integration challenges.

#4 Casdoor

Casdoor is a UI-first Identity Access Management (IAM) / Single-Sign-On (SSO) platform with web UI supporting OAuth 2.0, OIDC, SAML, CAS, LDAP, SCIM, WebAuthn, TOTP, MFA, RADIUS, Google Workspace, Active Directory and Kerberos.

Home page | GitHub Repo | Documentation | Discord community

Features of Casdoor

Protocols: OAuth 2.0, OIDC, SAML, CAS, LDAP, SCIM
Official SDKs: Android, iOS, React Native, Flutter, Firebase, Unity Games, uni-app, Electro, .Net Desktop, C/C++, Javascript, frontend-only, React, Next.js, Nuxt, Vue, Angular, Flutter, ASP.NET, Firebase, Go, Java, Node.js, Python, PHP, .NET, Rust, Dart, Ruby.
Authentication methods: Credentials, Email/SMS verification code, Social login (OAuth/SAML)
Identity management: Provides a centralized dashboard for managing users, roles, permissions, and multi‑tenant, and audit logs.
Customizable UI & flows: Provides pre-built UI templates and allows customization of login methods, registration fields, and authentication flows.
Access control: Supports RBAC and can integrate with fine‑grained authorization solutions (such as Casbin) for advanced permission management.
Multi-tenant: Enables managing multiple organizations or projects within a single instance.

Pros of Casdoor

Flexible integration: Casdoor’s rich API, SDK, Identity Provider support make it straightforward to integrate with various platforms and third‑party services.
Multi‑tenant & federation capabilities: Built-in multi-tenancy and identity brokering make it suitable for organizations managing multiple clients or subsidiaries.
Open Source & active community: Maintained by an engaged developer community, with discussions on platforms like Casnode and QQ groups, plus regular updates and contributions.

Cons of Casdoor

Security concerns: Has faced issues like SQL injection (CVE-2022-24124) and arbitrary file reading vulnerabilities, requiring strict security configurations and timely updates.
Outdated UI design: The prebuilt UI feels dated compared to modern authentication solutions, often requiring customization for a polished user experience.
Limited enterprise-grade support: While feature-rich, some advanced enterprise functionalities are less mature compared to more established platforms, sometimes requiring additional customization.
Steep learning curve: Advanced customization requires knowledge of Golang and React.js, which may be challenging for teams unfamiliar with these technologies. While Swagger API docs exist, detailed guides for complex use cases are lacking.

#5 Supertokens

A developer-centric auth solution blending open-source transparency with commercial scalability, offering passwordless, MFA, and session management optimized for modern app architectures.

Home page | GitHub Repo | Documentation | Discord community

Features of Supertokens

Protocols: OAuth 2.0
Framework & cloud integrations:
- Frameworks: Next.js App Router, Next.js Pages Router, NestJS, GraphQL, RedwoodJS, Capacitor.
- Cloud Platforms: AWS Lambda, Netlify, Vercel, Hasura, Supabase.
Authentication methods:
- Free: Password, email/SMS passwordless, social login.
- Paid: Multi-tenant authentication, enterprise SSO (SAML), MFA (TOTP/Email OTP/SMS OTP), account linking.
Pre-built UI components and customizable flows: Provides ready-to-use UI components for sign-in, sign-up, and password recovery. Allows developers to customize auth flows.
Multi-tenant support (Paid): Enables managing multiple tenants (organizations or applications) with enterprise SSO connecting via SAML, isolated user data, and unique login methods per tenant.
Risk assessment (Paid): Provides an Attack Protection Suite that analyzes login attempts and assigns risk scores. Can enforce additional security measures, such as requiring MFA.

Pros of Supertokens

Clear UI approach: Supertokens categorizes both SDKs and authentication methods into Pre-built UI and Custom UI, providing a clear and flexible integration experience.
Lightweight & authentication-focused: Designed exclusively for authentication, making it lightweight and efficient. The open-source version includes essential features, making it cost-effective for startups and small teams.
Active development: Regularly updated with new features and improvements, supported by an active GitHub community.

Cons of Supertokens

OSS features limitation: Need paid for advanced features like account linking, multi-tenant authentication, additional users for dashboard, MFA, and attack protection suite.
Limited enterprise integrations: No SAML application integration, which may reduce compatibility with legacy enterprise systems.
Narrower scope: Primarily focused on authentication, with only basic admin console features. Lacks advanced authorization, tenant management, and enterprise-grade identity features.
Smaller ecosystem: Fewer third-party integrations and plugins compared to comprehensive IAM solutions. Smaller community, which may impact long-term support and extensibility.

Conclusion

Open-source IAM solutions come in different types:

Comprehensive and extensible: e.g., Logto, Keycloak, and Casdoor, offering broader functionality for authentication, authorization, and user management.
Authentication/Authorization-only: e.g., Supertokens, focused solely on authN.
Lightweight, framework-specific: e.g., NextAuth.js, designed for specific frameworks.

When choosing a solution, consider your project size, specific requirements, and future scalability.

Logto stands out as a fully free and feature-rich OSS solution, with long-term stability, an active community, and full support for standard protocols. It offers a complete authentication, authorization, and user management suite, making it highly extensible. For those needing enterprise-grade compliance and reliability, Logto’s cost-effective Cloud version ensures seamless migration with dedicated support.

What is an IAM provider?#

Key considerations for choosing an open-source IAM solution#

The top 5 open-source IAM providers#

#1 Logto#

Key features of Logto OSS#

Pros of Logto OSS#

Cons of Logto OSS#

#2 Keycloak#

Features of Keycloak#

Pros of Keycloak#

Cons of Keycloak#

#3 Auth.js/NextAuth.js#

Features of NextAuth.js#

Pros of NextAuth.js#

Cons of NextAuth.js#

#4 Casdoor#

Features of Casdoor#

Pros of Casdoor#

Cons of Casdoor#

#5 Supertokens#

Features of Supertokens#

Pros of Supertokens#

Cons of Supertokens#

Conclusion#

What is an IAM provider?#

Key considerations for choosing an open-source IAM solution#

The top 5 open-source IAM providers#

#1 Logto#

Key features of Logto OSS#

Pros of Logto OSS#

Cons of Logto OSS#

#2 Keycloak#

Features of Keycloak#

Pros of Keycloak#

Cons of Keycloak#

#3 Auth.js/NextAuth.js#

Features of NextAuth.js#

Pros of NextAuth.js#

Cons of NextAuth.js#

#4 Casdoor#

Features of Casdoor#

Pros of Casdoor#

Cons of Casdoor#

#5 Supertokens#

Features of Supertokens#

Pros of Supertokens#

Cons of Supertokens#

Conclusion#

What is an IAM provider?

Key considerations for choosing an open-source IAM solution

The top 5 open-source IAM providers

#1 Logto

Key features of Logto OSS

Pros of Logto OSS

Cons of Logto OSS

#2 Keycloak

Features of Keycloak

Pros of Keycloak

Cons of Keycloak

#3 Auth.js/NextAuth.js

Features of NextAuth.js

Pros of NextAuth.js

Cons of NextAuth.js

#4 Casdoor

Features of Casdoor

Pros of Casdoor

Cons of Casdoor

#5 Supertokens

Features of Supertokens

Pros of Supertokens

Cons of Supertokens

Conclusion

What is an IAM provider?

Key considerations for choosing an open-source IAM solution

The top 5 open-source IAM providers

#1 Logto

Key features of Logto OSS

Pros of Logto OSS

Cons of Logto OSS

#2 Keycloak

Features of Keycloak

Pros of Keycloak

Cons of Keycloak

#3 Auth.js/NextAuth.js

Features of NextAuth.js

Pros of NextAuth.js

Cons of NextAuth.js

#4 Casdoor

Features of Casdoor

Pros of Casdoor

Cons of Casdoor

#5 Supertokens

Features of Supertokens

Pros of Supertokens

Cons of Supertokens

Conclusion