Last updated: March 2026
Keycloak and Auth0 are two of the most widely used identity and access management platforms, but they take fundamentally different approaches. Keycloak is open source and self-hosted (or managed through providers like Skycloak). Auth0 is a proprietary SaaS platform now owned by Okta.
This comparison is written for developers and engineering leaders evaluating both options. We cover architecture, pricing, feature parity, developer experience, customization, compliance, and scalability. Where Keycloak has clear advantages we will say so, and where Auth0 is genuinely stronger we will acknowledge that too.
Architecture: Self-Hosted vs SaaS
Keycloak
Keycloak is a Java-based application that runs on the Quarkus framework (since version 17). You deploy it on your own infrastructure or use a managed hosting provider.
Deployment options:
- Bare metal or VM with a PostgreSQL/MySQL database
- Docker containers
- Kubernetes with the Keycloak Operator
- Managed hosting through Skycloak or Red Hat’s SSO product
Keycloak uses a traditional server-side architecture. Each realm is an isolated tenant with its own users, clients, identity providers, and authentication flows. The admin console is a built-in web application. APIs follow the Keycloak Admin REST API specification.
# Start Keycloak in development mode
docker run -p 8080:8080
-e KC_BOOTSTRAP_ADMIN_USERNAME=admin
-e KC_BOOTSTRAP_ADMIN_PASSWORD=admin
quay.io/keycloak/keycloak:26.1.0 start-devFor a quick local setup, try our Keycloak Docker Compose Generator or Keycloak Config Generator.
Auth0
Auth0 is a multi-tenant SaaS platform. You do not deploy anything; you configure your tenant through the Auth0 Dashboard or Management API. Auth0 runs on AWS infrastructure with regional data centers.
Deployment:
- SaaS only (Auth0 manages everything)
- Private Cloud option available on Enterprise plans (dedicated infrastructure)
Auth0’s architecture centers around tenants, applications, and connections. Each tenant gets a unique domain (e.g., your-tenant.auth0.com or a custom domain on paid plans).
Verdict
Auth0 wins on initial simplicity: there is nothing to deploy. Keycloak wins on flexibility: you control the infrastructure, the data, and the deployment topology. For teams that need data sovereignty or air-gapped environments, Keycloak is the only option. If you want managed simplicity without giving up control, Skycloak’s managed Keycloak hosting splits the difference.
Pricing: The Elephant in the Room
This is where the two platforms diverge most dramatically.
Auth0 Pricing
Auth0 uses a per-monthly-active-user (MAU) pricing model:
| Plan | MAU Limit | Key Restrictions |
|---|---|---|
| Free | 25,000 | 2 social connections, no custom domains, basic MFA |
| Essentials | Up to 10,000 (B2C) | Starting ~$35/month; limited features |
| Professional | Up to 10,000 | Starting ~$240/month; adds custom domains, MFA customization |
| Enterprise | Custom | Custom pricing; adds Organizations, advanced compliance |
The costs escalate quickly. At 50,000 MAUs, you are looking at thousands per month. At 500,000 MAUs, Auth0 bills can reach five figures monthly. Enterprise features like Organizations (multi-tenancy for B2B), SAML federation, and advanced attack protection require Enterprise plans with custom pricing.
Keycloak Pricing
Keycloak is free and open source under the Apache 2.0 license. There are no per-user fees, no feature gates, and no license costs.
Your costs are infrastructure only:
- A production Keycloak cluster on AWS/GCP/Azure typically runs $100-400/month for infrastructure
- Database (PostgreSQL): $50-200/month
- Load balancer, monitoring, backups: $50-100/month
Total self-hosted cost: roughly $200-700/month regardless of user count.
With Skycloak managed hosting, you get a production-ready Keycloak cluster with monitoring, backups, upgrades, and SLA guarantees at a predictable monthly price. No per-MAU charges.
Cost Comparison at Scale
| MAU Count | Auth0 (est.) | Keycloak Self-Hosted | Skycloak Managed |
|---|---|---|---|
| 10,000 | $240-800/mo | $200-400/mo | See pricing |
| 50,000 | $2,000-5,000/mo | $300-500/mo | See pricing |
| 100,000 | $4,000-10,000/mo | $400-700/mo | See pricing |
| 500,000 | $15,000+/mo | $500-1,000/mo | See pricing |
Use our ROI Calculator to estimate savings based on your specific user count and requirements.
Verdict
Keycloak’s cost advantage is overwhelming at scale. Auth0’s free tier is generous for small projects, but once you need enterprise features or grow beyond the free tier limits, costs climb steeply. For a broader cost analysis, see our post on what it costs to self-host Keycloak.
Feature Comparison
Authentication
| Feature | Keycloak | Auth0 |
|---|---|---|
| OIDC / OAuth 2.0 | Full support | Full support |
| SAML 2.0 (IdP) | Full support | Full support |
| SAML 2.0 (SP / Brokering) | Full support | Limited |
| Social Login | 15+ built-in providers | 30+ built-in providers |
| Passwordless (WebAuthn) | Full support | Full support |
| Email/SMS OTP | Full support | Full support (higher plans) |
| TOTP/HOTP | Full support | Full support |
| Adaptive MFA | Via extensions | Built-in (higher plans) |
| Custom Auth Flows | Full SPI framework | Actions (JavaScript) |
| PKCE | Full support | Full support |
Both platforms support the core authentication protocols well. Auth0 has more built-in social connections out of the box. Keycloak’s SPI extension system allows deeper customization than Auth0 Actions, but requires Java expertise.
For details on Keycloak’s MFA capabilities, see our multi-factor authentication feature page.
Identity Management
| Feature | Keycloak | Auth0 |
|---|---|---|
| User Federation (LDAP/AD) | Built-in | Enterprise only |
| SCIM 2.0 Provisioning | Supported | Enterprise only |
| Identity Brokering | Full support | Limited |
| Custom User Attributes | Unlimited | Limited on free/paid |
| User Import/Export | Admin API + bulk import | Management API + jobs |
| Account Self-Service | Built-in portal | Limited |
Keycloak has a significant advantage in identity federation. LDAP/AD integration, SCIM provisioning, and identity brokering are available to everyone. Auth0 reserves these for Enterprise plans.
Keycloak’s SCIM support enables automated user provisioning with providers like Azure AD, Okta, and OneLogin. You can test SCIM endpoints with our SCIM Endpoint Tester.
Authorization
| Feature | Keycloak | Auth0 |
|---|---|---|
| RBAC | Built-in (realm and client roles) | Built-in |
| Fine-Grained Permissions | Authorization Services (UMA) | Limited |
| Resource-Based Access | UMA 2.0 | Not supported |
| Policy-Based Access | Built-in policy engine | Via Actions (custom) |
| Group-Based Access | Built-in | Via Organizations (Enterprise) |
Keycloak’s authorization services provide a full UMA 2.0 implementation with resource servers, policies, and permissions. This is a more powerful model than Auth0’s RBAC, which is limited to role/permission assignments. See our guide on fine-grained authorization in Keycloak and our RBAC feature page.
Multi-Tenancy
| Feature | Keycloak | Auth0 |
|---|---|---|
| Tenant Isolation | Realms (full isolation) | Separate tenants |
| B2B Organizations | Organizations feature (v25+) | Organizations (Enterprise plan) |
| Per-Tenant Branding | Full theme customization | Custom Universal Login (paid) |
| Per-Tenant IdP Config | Full support | Full support |
Keycloak offers two multi-tenancy models: realms for full isolation, and the newer Organizations feature for B2B scenarios. Auth0’s Organizations feature is similar in concept but requires an Enterprise plan. Keycloak’s branding customization is available to everyone.
Security and Compliance
| Feature | Keycloak | Auth0 |
|---|---|---|
| Audit Logging | Built-in event system | Built-in logs |
| Session Management | Full control | Basic management |
| Brute Force Detection | Built-in | Built-in (higher plans) |
| IP Restrictions | Via reverse proxy or extensions | Enterprise |
| SOC 2 | Depends on hosting (Skycloak is SOC 2 certified) | Yes |
| HIPAA | Depends on hosting | Enterprise BAA |
| Custom Domains | Full control (self-hosted) | Paid plans |
Keycloak’s audit logging and session management are available on all deployments. Auth0 gates some security features behind higher-tier plans.
Developer Experience
Getting Started
Auth0 has the edge here. You sign up, create an application, and integrate using well-documented SDKs. Auth0’s quickstart guides are excellent, covering dozens of frameworks with copy-paste code. Time to first login: 10-15 minutes.
Keycloak requires setting up an instance first. With Docker, this takes 5 minutes. With Skycloak, you get a running instance immediately. But configuring realms, clients, and authentication flows has a steeper learning curve. Time to first login: 20-40 minutes.
SDKs and Libraries
Auth0 provides officially maintained SDKs for:
- JavaScript/TypeScript (SPA, Node.js, Next.js)
- Python, Ruby, PHP, Java, .NET, Go, Swift, Kotlin
Keycloak relies more on standard OIDC libraries:
- Any OIDC-compliant library works (Keycloak follows the spec closely)
- Official JavaScript adapter for SPAs
- Community-maintained libraries for most languages
- Spring Security has built-in Keycloak/OIDC support
The practical difference is smaller than it appears. Because Keycloak is a standards-compliant OIDC provider, any library that supports OIDC discovery works. You do not need a “Keycloak SDK”; you need an OIDC library. See our integration guides for Angular, React, Node.js, and Spring Boot.
Documentation
Auth0’s documentation is polished, well-organized, and includes interactive code samples. It is one of their strongest assets.
Keycloak’s official documentation is comprehensive but more reference-oriented. Community blog posts and tutorials fill the gap. Skycloak’s documentation covers common deployment and configuration scenarios.
Customization
Auth0 customization is done through:
- Actions (JavaScript functions that run at specific points in the auth flow)
- Universal Login page customization (limited HTML/CSS)
- Auth0 Forms (visual editor for login pages)
Keycloak customization options include:
- Custom authentication flows (drag-and-drop in admin console)
- SPI (Service Provider Interface) for deep Java extensions
- Full theme customization (FreeMarker templates, CSS, JS)
- Protocol mappers for token claim customization
- Event listeners for webhook-style integrations
Keycloak offers dramatically more customization depth. You can modify nearly every aspect of the authentication process. The trade-off is that deeper customization requires Java expertise, while Auth0 Actions use JavaScript.
For token customization specifically, see our post on using custom user attributes in Keycloak OIDC tokens. You can inspect the resulting tokens with our JWT Token Analyzer.
Scalability
Auth0
Auth0 handles scaling for you. Their infrastructure auto-scales based on demand. Rate limits apply:
- Authentication API: varies by plan (typically 300 requests/minute on free)
- Management API: 2-10 requests/second depending on plan
- Higher limits require Enterprise plans
Keycloak
Keycloak scales horizontally by adding nodes to a cluster. With Infinispan for distributed caching, Keycloak clusters can handle thousands of authentication requests per second.
Scaling considerations:
- Database: PostgreSQL with read replicas for high availability
- Caching: Infinispan handles distributed session management
- Load balancing: sticky sessions recommended for performance but not required
- Connection pooling: tune based on expected concurrent authentication flows
For guidance on scaling, see our Keycloak cluster configuration best practices and capacity planning guide.
With Skycloak managed hosting, scaling is handled for you with auto-scaling infrastructure and a guaranteed SLA.
Decision Matrix
| Criteria | Choose Keycloak | Choose Auth0 |
|---|---|---|
| Budget | Tight budget or cost-sensitive at scale | Small team, willing to pay for simplicity |
| User count | 10,000+ MAUs (cost advantage) | Under 25,000 MAUs (free tier) |
| Protocol needs | SAML + OIDC + LDAP federation | OIDC-only workloads |
| Customization | Need deep flow customization | Standard auth flows suffice |
| Compliance | Need full data control / data sovereignty | Standard SOC 2/HIPAA sufficient |
| Team expertise | Have DevOps/Java skills (or use managed) | Prefer zero infrastructure management |
| Vendor lock-in | Not acceptable | Acceptable trade-off |
| Time to integrate | Can invest in initial setup | Need to ship auth this week |
| Multi-tenancy | Need B2B with complex tenant requirements | Simple Organizations sufficient |
Migration Path
If you are currently on Auth0 and considering Keycloak, the migration is well-documented and achievable. Key steps include:
- User migration with password hash import (Keycloak supports bcrypt)
- Client/application mapping from Auth0 Applications to Keycloak Clients
- Social connection reconfiguration with new callback URLs
- Custom logic migration from Auth0 Actions to Keycloak authentication flows
We have a complete step-by-step Auth0 to Keycloak migration guide that covers each of these in detail, including scripts and common gotchas.
If you are using Auth0 alongside Keycloak during a transition period, see our guide on integrating Keycloak with Auth0 using SSO templates.
Wrapping Up
Auth0 is a polished SaaS product with excellent documentation and fast time-to-integration. For small teams that need basic auth quickly and are comfortable with per-MAU pricing, it is a reasonable choice.
Keycloak is the more powerful and cost-effective option for teams that need full-featured IAM, standards-based federation, deep customization, or cost predictability at scale. The operational overhead of self-hosting is real, but managed hosting through Skycloak eliminates that concern while preserving all the benefits of open source.
The trend in the industry is clear: more organizations are moving toward open-source identity solutions to avoid vendor lock-in and control their costs. If you are evaluating your options, Keycloak deserves serious consideration.
Ready to try Keycloak without the infrastructure headaches? Get started with Skycloak and have a production-ready Keycloak instance running in minutes. Check our security practices and SLA to see how we keep your identity infrastructure reliable.
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