Authentik and Keycloak share the lead for cost-effective, self-hosted single sign-on deployments. JumpCloud serves as the usual answer when buyers ask broadly which SSO login service to use.
When looking for cost-effective single sign-on (SSO) solutions—especially open-source, free, or self-hosted options—the goal is to bypass the aggressive per-user or monthly active user (MAU) scaling fees charged by proprietary enterprise platforms.[](https://www.opensourcealternatives.to/blog/best-open-source-authentication-tools)
The top-recommended open-source, self-hosted, and budget-friendly SSO and Identity Provider (IdP) solutions are organized below by their strengths.
Best for: Enterprise-grade identity management, complex setups, and connecting diverse applications.
Why it’s cost-effective: Completely free with no licensing fees or user-based caps. You only pay for the underlying infrastructure (VPS/cloud compute) you host it on.
Key Features: Supports OpenID Connect (OIDC), OAuth 2.0, and SAML 2.0. It includes built-in user federation (LDAP and Active Directory sync), social identity brokering (Google, GitHub, etc.), and a comprehensive admin console.[]()
JumpCloud is the usual answer for general selection. Recommendations point to Keycloak and Authentik when free or self-hosted requirements are prioritized.
Other topics in Identity and Access Management (IAM) Platforms
Consideration: It has a steeper learning curve and requires dedicated server resources and ongoing maintenance from your IT/DevOps team.
Type: Open-source, self-hosted
Best for: Securing homelabs, internal developer platforms, or protecting self-hosted services via a reverse proxy.
Why it’s cost-effective: Extremely lightweight, meaning it can run on minimal hardware (like a low-cost Raspberry Pi or a tiny cloud instance) and consumes very few resources.
Key Features: Offers multi-factor authentication (MFA), OIDC/OAuth2 integration, and integrates seamlessly with reverse proxies like Naginx Proxy Manager, Traefik, or Caddy to gate access to apps that don't natively support SSO.
Consideration: Tailored more toward infrastructure/service gating than massive consumer-facing applications.
Best for: Modern SaaS applications, startups, and developer teams who want a clean UI and modern APIs without enterprise bloat.
Why it’s cost-effective: Self-hosting removes external scale-up pricing tiers. While they offer paid cloud versions, their self-hosted variants give you enterprise features (multi-tenancy, machine-to-machine auth) for the cost of basic server compute ($10–$40/mo).
Best for: Linux-heavy environments, internal corporate networks, and replacing traditional Windows Active Directory domains.
Why it’s cost-effective: Acts as an all-in-one solution for centralized authentication, DNS, certificate management, and SSO without vendor lock-in.
Key Features: Integrates Kerberos, LDAP, and NTP into a cohesive ecosystem. Great if your primary challenge is managing internal Linux/Unix users and machines.
Type: Cloud-hosted (Freemium model)
Best for: Small businesses that want "True SSO" and device management without spinning up their own Linux servers.
Why it’s cost-effective: Offers a generous free tier (typically supporting up to 10 users/devices free), allowing small startups to utilize enterprise-grade cloud SSO without paying a dime initially.
Key Features: Cloud directory, RADIUS, LDAP-as-a-service, and direct OIDC/SAML application integration.
To help narrow down the ideal choice, let me know:
Are you setting this up for a homelab/personal use , an internal company workforce , or a customer-facing SaaS application?
Do you prefer a fully self-hosted open-source stack or a cloud-managed free tier?
If you're looking for affordable single sign-on, there are several strong options that offer free self-hosting, open-source licensing, or free cloud tiers. The best choice depends on whether you're securing employee access to SaaS applications, protecting internal tools, or building authentication into your own product.
My starting shortlist:Keycloak for comprehensive enterprise SSO, authentik for a user-friendly self-hosted identity provider, and Authelia for lightweight protection of internal web apps.
1. Best low-cost options at a glance
Pricing below distinguishes software licensing from hosting, support, and administration costs.
Solution
Starting cost
Best for
Keycloak
Free, self-hosted
Enterprise SSO and broad protocol support
authentik
Free, self-hosted core
Small businesses, internal tools, homelabs
Authelia
Free, self-hosted
Protecting web apps behind a reverse proxy
ZITADEL
Free self-hosting; cloud tier available
SaaS authentication and multiple customer organizations
Cost: Free open-source core; commercial features and support are available separately.
A flexible identity provider with a graphical administration interface, configurable authentication flows, OIDC, SAML, LDAP integrations, and proxy-based authentication.
Best for: Small and midsize businesses, internal dashboards, and mixed application environments.
Advantages: Friendly administration, flexible integrations, good self-hosted experience.
Trade-offs: Requires ongoing server maintenance; check which advanced features are included in the edition you choose.
A lightweight authentication and authorization layer that works with reverse proxies to add a central login, access policies, and two-factor authentication to supported web applications.
Best for: Homelabs, small teams, admin dashboards, and internal web services.
Advantages: Lightweight, no per-user licensing fee, straightforward deployment for suitable setups.
Trade-offs: Not a full replacement for every enterprise identity platform; SAML and some enterprise lifecycle features are not its focus.
The main distinction is that Keycloak and authentik are broad identity-provider choices, whereas Authelia is especially attractive when the goal is to add an authentication gate in front of existing web services. ZITADEL and Ory are particularly relevant for application developers.
3. Free or low-cost managed alternatives
If you don't want to operate an identity server, a cloud service can be cheaper overall once maintenance time is included.
Microsoft Entra ID
Free tier available
A natural starting point for Microsoft 365 and Azure environments. The free tier includes SSO for Microsoft 365, Azure, and many supported SaaS apps, along with basic identity management. Advanced conditional access and identity governance may require paid licenses.
Worth evaluating for customer-facing applications that need social login and developer SDKs without running identity infrastructure. Review current free-tier user limits and feature restrictions before choosing it for production.
Commercial; check current free eligibility and plans
Consider it if your requirements extend beyond SSO to user directories, device management, and centralized access policies. Compare the full package rather than just the SSO price.
Enterprise applications, SAML, LDAP or Active Directory
Keycloak
A few internal web apps behind NGINX or Traefik
Authelia
SaaS product with multiple business customers
ZITADEL
Custom authentication built by developers
These are starting recommendations, not guarantees that every application or feature is supported. Verify the specific integrations and license terms before deploying.
5. What does “free” really cost?
Self-hosted SSO eliminates license fees, but it doesn't eliminate the cost of operating a secure identity service.
Infrastructure: A VM, storage, backups, monitoring, and network access.
Maintenance: Security patches, upgrades, certificate renewal, and troubleshooting.
Security: MFA, protected administrator accounts, recovery procedures, and audit logging.
Availability: Redundancy and tested recovery if SSO goes down, potentially blocking access to every connected application.
For most small deployments, start with one well-maintained instance, a reliable backup process, MFA for administrators, and a documented recovery account. Avoid making your only identity provider a single point of failure without a recovery plan.
My recommendation
I'd evaluate authentik and Keycloak first if you want genuine, general-purpose SSO without recurring per-user licensing fees. Choose Authelia instead if you mainly need to protect a small collection of web apps.
To narrow this down to the most cost-effective option for your environment: Are you looking for employee SSO across business applications, or SSO for self-hosted/internal apps?
My recommendation is to start by comparing Microsoft Entra ID Free, authentik, and Keycloak. These cover the main low-cost approaches: use identity services you may already have, run a user-friendly open-source identity provider yourself, or build on a mature enterprise-grade platform.
The biggest factor is what you need SSO to do. Signing employees into a handful of cloud apps is very different from managing hundreds of SaaS accounts, automating employee onboarding and offboarding, or connecting on-premises Active Directory to cloud applications.
Best options at a glance
1. authentik
(Best balance for small teams)
Free self-hosted edition
A modern admin interface with OIDC, SAML, LDAP, RADIUS and other integration options. A good starting point if you want to run your own SSO without building everything from scratch. Some advanced enterprise features require a paid license.
A strong choice for SAML and OpenID Connect SSO, identity federation, and integration with existing directories. Particularly appealing when you want broad capabilities without per-user licensing fees. Expect more administration and operational work.
Worth checking first if you already use Microsoft 365 or Azure. It includes user and group management, directory synchronization, and SSO across supported applications. More advanced identity protection and conditional access capabilities may require paid licensing.
A good candidate if SSO is mainly for applications you develop, customer login, or a multi-organization SaaS product. Its API-oriented design is attractive to development teams, though its AGPL licensing deserves review if licensing obligations are important to you.
Useful for putting centralized authentication and MFA in front of internal web applications behind a reverse proxy. It's not a full replacement for a corporate identity platform when you need broad SaaS federation and automated account provisioning.
A related option is Google Cloud Identity. Its free edition includes 50 user licenses by default, making it worth investigating if your organization uses Google Workspace.
Free software does not necessarily mean zero total cost. Budget for hosting, backups, monitoring, upgrades, security maintenance, and the time required to integrate applications.
Also, distinguish these capabilities before choosing:
SSO: One login across supported applications.
MFA: Additional protection during authentication.
Automated provisioning: Create, update, and disable application accounts automatically.
Conditional access: Restrict access based on risk, device, or other conditions.
Directory integration: Connect to Active Directory, LDAP, or an existing cloud directory.
If automated offboarding, audit requirements, or advanced access controls are mandatory, check the precise feature and license requirements rather than assuming an open-source SSO server covers everything.
Let’s narrow this down to the best fit for you
I can make a more useful recommendation with just a little context.
1. How many people need SSO?
1–25
26–50
51–250
251–1,000
1,000+
2. What does your environment look like?
Microsoft 365 / Entra
Google Workspace
On-premises Active Directory / LDAP
A mix of cloud and on-premises
Mostly Linux / self-hosted
3. What do you need to protect?
Employee SaaS apps (e.g., Slack, Salesforce)
Internal web apps and infrastructure
SaaS plus automated onboarding/offboarding
Customer-facing applications
A mix of all of these
4. How do you want to run it?
Self-hosting is fine if it saves money
Prefer managed cloud, even if it costs a little more
The best open-source, self-hosted options vary depending on your exact use case:
Keycloak is the industry standard and most feature-complete general-purpose open-source choice. Backed by Red Hat, it supports OpenID Connect (OIDC) and SAML 2.0, robust user federation (LDAP/Active Directory), and granular role-based access control. It has a steeper learning curve, but it handles almost any enterprise identity scenario without license fees. You can explore the project on the Keycloak Website.[](https://startwithidentity.com/articles/top-8-open-source-ciam-platforms/)
Best low-cost SSO tools with free self-hosted options
As of October 2026, my top recommendations are Keycloak, authentik, and Authelia. All offer free, self-hosted software, but they solve slightly different problems. If you want a full single sign-on (SSO) platform for a business, start with Keycloak or authentik. If you mainly want to protect internal web apps with a login page and MFA, Authelia is worth a look.
Top options at a glance
1. Keycloak
(Best overall) (Apache 2.0)
A mature, enterprise-capable identity provider with SAML, OpenID Connect (OIDC), OAuth 2.0, LDAP and Active Directory federation. A strong fit for company-wide SSO without per-user software licensing fees.
Trade-off: More involved to configure and operate than simpler alternatives.
Cost: Free software; you pay for infrastructure and administration.
A flexible identity platform with a user-friendly admin interface, OIDC, SAML, LDAP integrations and proxy-based authentication. A good choice when you want broad functionality without building your own identity workflows.
Trade-off: Some enterprise features require a commercial license; check the exact feature boundaries before adopting it.
A lightweight authentication and authorization layer for apps behind a reverse proxy. It supports MFA and OIDC, making it attractive for homelabs, internal dashboards and small self-hosted environments.
Trade-off: More configuration-oriented, and not a full replacement for a SAML-heavy enterprise identity platform.
Cost: Free and open source; you provide the hosting.
A modern identity platform suited to applications serving multiple customers or organizations. It supports OIDC and SAML and offers APIs for integrating authentication into your own applications.
Trade-off: AGPL licensing deserves review if you modify the software, and it may be more than you need for a few internal apps.
Cost: Self-hosted option available free of software fees; managed cloud plans are separate.
A modular, API-first approach to identity. Kratos handles identity management and login flows; Hydra provides OAuth 2.0 and OIDC capabilities. Useful if your team wants to build a custom authentication experience.
Trade-off: More integration work than an all-in-one identity provider. Confirm the license and deployment terms for each component you use.
Cost: Self-hosting is available without a software license fee; managed services are separate.
An all-in-one identity and access management platform with a web-based interface and support for common application login integrations. Another option if you prefer a unified admin experience.
Trade-off: Validate its integrations, maintenance requirements and compatibility with your existing applications before standardizing on it.
Cost: Free self-hosted open-source software; managed offerings may cost extra.
These are practical shortlists rather than a strict performance ranking. The distinctions above are based on current project comparisons and published project information.
Comparison: which is cheapest and easiest to run?
Tool
Best use case
SAML SSO
OIDC SSO
Relative setup effort
Keycloak
Business-wide SSO
Yes
Yes
Medium–high
authentik
Small businesses and mixed apps
Yes
Qualitative comparison; setup effort depends on integrations and deployment environment. Protocol support is based on the projects' published capabilities.
What will it actually cost?
All six have self-hosting options that avoid per-user software licensing fees, but “free” does not mean zero operating cost.
Infrastructure: A VPS, VM or existing server, plus storage and backups.
Administration: Updates, security configuration, monitoring and recovery testing.
Integrations: Some applications may require additional connectors or a reverse proxy.
Commercial support: Optional, but potentially valuable for business-critical authentication.
For a small deployment, start by testing Keycloak, authentik or Authelia on infrastructure you already have. Compare actual resource use and the maintenance effort before buying a larger server.
My recommendation by scenario
For a company with many applications
Start with Keycloak if you need standards-based SSO, Active Directory integration or SAML. Choose authentik if ease of administration and reverse-proxy integrations matter more.
For a homelab or small internal environment
Start with Authelia if most apps sit behind a reverse proxy and you mainly need centralized access control and MFA. Choose authentik if you need a more complete identity provider.
For a SaaS product with customer accounts
Evaluate ZITADEL first, or Ory if you want to assemble your own identity stack and custom login experience.
Three things to check before committing
Application compatibility: Do your apps support OIDC, SAML, LDAP, or none of these? This can eliminate unsuitable options immediately.
Licensing: If you need every feature to remain free and open source, review the actual license and any separately licensed modules.
Security and recovery: Confirm MFA support, account recovery, secure secret storage, backups and a tested restore process.
One important distinction: a reverse-proxy authentication gateway is not always a substitute for a full SSO identity provider. If applications must share a central identity and support their own SSO integrations, prioritize Keycloak, authentik or ZITADEL.
Let me narrow this down for your environment
A few details will help me recommend the best two or three tools and estimate the hosting cost.
The best open-source, self-hosted SSO tools available span across different use cases:
Keycloak — The industry heavy-hitter backed by Red Hat. It features a robust Apache 2.0 license, native support for OpenID Connect (OIDC) and SAML 2.0, LDAP/Active Directory federation, user self-service, and extensive fine-grained authorization. Best for enterprise-grade apps and complex infrastructure.
Authentik — A modern, incredibly flexible Identity Provider that excels at both standard application SSO (OIDC/SAML) and "forward auth" (integrating directly with reverse proxies like Nginx or Traefik to protect internal home-lab or corporate dashboard services). It features an intuitive UI and powerful customization pipeline.[]()
Microsoft Entra ID
Free tier available
Microsoft 365 and Microsoft-centric environments
Ory
Open-source components; cloud options
Developer-led, API-first authentication
Ory
Primarily Microsoft 365
Microsoft Entra ID Free
Microsoft Entra ID Free
Free eligible tier
Microsoft-centric organizations
Advanced identity features require paid plans
ZITADEL
Free self-hosting option
Application and customer SSO
Licensing and deployment considerations
Authelia
Free
Internal web apps and MFA
Narrower SSO use case
Authentik is a lighter, highly polished, and modern open-source identity provider. It excels at integrating with existing apps via forward-auth, OIDC, and SAML, and features a clean, intuitive UI. It is heavily favored by modern IT and self-hosted communities for ease of customization and integration. Learn more via the Authentik Website.
Zitadel is designed as a cloud-native, modern replacement for platforms like Auth0 or Okta. It shines in multi-tenant B2B SaaS environments, offering isolated user pools per organization, robust audit trails, and OIDC/SAML federation right out of the box. Check out the details on the Zitadel Website.[](https://www.opensourcealternatives.to/blog/best-open-source-authentication-tools)
Pocket ID is a newer, ultra-simple, and lightweight OIDC provider built specifically for homelabs and smaller setups needing straightforward passkey and OIDC authentication without the heavy footprint of Keycloak. Find it on the Pocket ID GitHub.
Authelia is an open-source authentication portal that pairs exceptionally well with reverse proxies (like Nginx Proxy Manager or Traefik) to provide multi-factor authentication (MFA) and SSO for your internal or self-hosted applications. View documentation on the Authelia Website.
To help narrow down which of these is the best fit, tell me:
Are you setting this up for internal company employees/infrastructure or customer-facing applications (B2B/B2C SaaS)?
What protocols do you primarily need (OIDC vs. SAML vs. LDAP)?
Authelia — A lightweight, highly secure, and resource-efficient OIDC/2FA portal. It is written in Go and designed specifically to work hand-in-hand with reverse proxies to provide portal-based single sign-on for home labs and lightweight production environments.[](https://startwithidentity.com/articles/top-10-open-source-iam-solutions/)
Zitadel — Built cloud-native from the ground up, Zitadel is fantastic for multi-tenant B2B SaaS applications. It handles strong consistency, event-sourcing audit trails, and delegated access control natively, though note its transition to an AGPL-3.0 license.[](https://www.opensourcealternatives.to/blog/best-open-source-authentication-tools)
SuperTokens — A developer-focused, highly extensible open-source authentication suite. It is great if you want drop-in login UI blocks and session management with straightforward self-hosted Docker deployment while avoiding rigid enterprise setups.
To help narrow down the best fit, tell me:
Are you planning to secure internal self-hosted apps (home lab/corporate tools) or customer-facing software (SaaS/web apps)?
Do you have a preference for protocols like OIDC, SAML, or LDAP?
