Auth0 vs Clerk vs Firebase Authentication vs Keycloak vs Supabase Auth vs WorkOS: Which Alternative is Best? (2026)

No, Auth0 is primarily a cloud-based identity platform and does not offer a fully self-hosted version. While you can customize and extend Auth0 via rules and hooks, the core authentication and user data storage remain managed by Auth0's cloud infrastructure. Organizations requiring full on-premises control should consider alternative open-source identity providers.

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Auth0 requires internet connectivity to perform authentication flows since it relies on its cloud service to validate credentials and tokens. There is no built-in offline mode or local token validation. For use cases requiring offline authentication, you would need to implement a local identity solution or cache tokens externally, but this is not natively supported by Auth0.

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Auth0 allows exporting user data via its Management API, including bulk user exports in JSON or CSV formats. However, the process can be rate-limited and may require pagination for large datasets. While you retain ownership of your data, it resides in Auth0's infrastructure, so compliance and data residency should be evaluated carefully. Full data export is possible but may require scripting and handling API constraints.

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Yes, Auth0 enforces rate limits on its Management and Authentication APIs, which vary based on your subscription plan. Free and lower-tier plans have stricter limits, which can impact high-volume applications. Enterprise plans offer higher thresholds. It's important to design your integration to handle rate limiting gracefully and consider plan upgrades as usage grows.

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Auth0 supports user migration via bulk export of user profiles and credentials (password hashes) through the Management API. For password migration, Auth0 provides a seamless migration feature where users' passwords are verified against the legacy system on first login and then imported into Auth0. Moving away from Auth0 requires exporting user data and adapting password hashes to the new system's format, which can be complex depending on the hashing algorithms used.

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Clerk is primarily a cloud-based platform with limited self-hosting options. Currently, it does not offer a fully self-hosted version, so teams requiring complete on-premise control may find it restrictive.

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No, Clerk's authentication services depend on cloud infrastructure and require internet connectivity. It does not support offline or air-gapped deployments, making it unsuitable for environments without reliable network access.

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User data in Clerk is stored on their cloud servers, and while developers retain ownership of their user data, Clerk acts as a data processor under GDPR and similar regulations. They provide compliance features, but teams should review their data handling policies to ensure alignment with privacy requirements.

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Yes, Clerk enforces API rate limits to protect service stability, which vary depending on your subscription plan. The limits are generally sufficient for typical applications but may require adjustment or negotiation for high-volume use cases.

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Clerk supports importing user data through CSV and JSON formats and provides export capabilities via their dashboard and API. However, migration tools are somewhat manual and may require custom scripting for complex scenarios.

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Firebase Authentication is a fully managed service by Google and does not support self-hosting or offline operation. All authentication flows require connectivity to Firebase backend servers, so it is not suitable for environments requiring offline or isolated deployments.

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User data in Firebase Authentication is stored on Google's servers under Firebase's terms. You can export user account data via the Firebase Admin SDK or REST API, but there is no built-in tool for full data migration to other identity providers. Data ownership remains with the project owner, but vendor lock-in is a consideration.

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Firebase Authentication provides REST APIs and Admin SDKs for user management and token verification, but it lacks advanced IAM features like SCIM provisioning or fine-grained enterprise policies. Custom backend integrations must handle token validation and user state accordingly, as the API surface is focused on common auth flows rather than complex identity management.

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Firebase Authentication does not offer a direct migration tool to export and import users into other identity providers. The typical approach involves exporting user data via Admin SDK, then scripting user creation in the new system. Password hashes are not exportable, so users may need to reset passwords after migration.

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Setting up Keycloak for high availability requires configuring a clustered environment with shared database and session replication. You need to manage load balancing, database failover, and ensure consistent cache synchronization. This demands solid internal operations expertise, especially for tuning performance and handling failover scenarios. Keycloak does not provide built-in HA orchestration, so you must implement and monitor these components yourself.

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Keycloak supports offline tokens (offline refresh tokens) that allow clients to obtain new access tokens without user interaction, but initial authentication and token issuance require connectivity to the Keycloak server. For truly offline authentication, Keycloak is not designed to function without network access to its services, as it relies on centralized token validation and user federation.

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When self-hosting Keycloak, you retain full ownership and control over all user data since it is stored in your chosen database backend. Keycloak supports export and import of user data and configuration via its export/import commands and partial export APIs, enabling migration between instances or backups. However, the export format is JSON-based and may require custom scripts for complex migrations.

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Keycloak provides comprehensive REST APIs for user management, authentication flows, and token operations, but some advanced features like fine-grained admin operations or custom authenticator management may require direct database access or custom SPI extensions. Rate limiting and pagination on some endpoints are limited, so large-scale integrations should implement their own throttling and caching.

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Self-hosting Supabase Auth requires deploying the Supabase Auth Docker container along with its dependencies like Postgres and the GoTrue API. While Supabase provides Docker Compose configurations for local development, a fully on-premise production setup demands configuring secure networking, SSL termination, and scaling considerations. The process is moderately complex and best suited for teams familiar with container orchestration and PostgreSQL management.

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Supabase Auth primarily relies on JWT tokens issued by the server which can be validated locally by clients without network calls, enabling offline session validation. However, initial authentication flows (email/password, OAuth) require network connectivity to the Supabase Auth API. Offline usage is limited to token verification and session management on the client side.

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User data in Supabase Auth is stored in your own PostgreSQL database, so you retain full ownership and control. Exporting user data is straightforward via SQL queries or database dumps. Migration to other authentication systems requires exporting user credentials and metadata, but password hashes are stored in standard formats compatible with many systems, easing migration efforts.

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The managed Supabase Auth service enforces soft rate limits to protect against abuse, but these limits are generally high and suitable for most modern web applications. The API supports standard authentication flows but lacks some advanced enterprise IAM features like granular role delegation or multi-tenant management. For heavy enterprise use cases, additional tooling or custom solutions may be necessary.

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WorkOS is a cloud-based platform and does not offer a fully self-hosted deployment option. Its architecture relies on managed infrastructure to handle SSO, SCIM provisioning, and directory sync, so if you require a fully self-hosted stack for compliance or control reasons, WorkOS may not be suitable.

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WorkOS does not support offline authentication or local caching of SSO sessions. Since it acts as a cloud intermediary for enterprise identity providers, an active internet connection is required for authentication flows to complete successfully.

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User identity data processed through WorkOS remains the property of the SaaS application using the platform. WorkOS provides APIs for SCIM provisioning and directory sync, enabling synchronization and export of user data to your systems. However, full data export or migration depends on your implementation of these APIs and the connected identity providers.

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WorkOS enforces rate limits on its APIs to ensure stability and fair usage, but these limits are generally sufficient for typical B2B SaaS workloads. The exact thresholds depend on your subscription plan and can be discussed with their sales team. Additionally, some advanced features may require specific API calls that need careful integration to avoid hitting limits.

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