# Multi-Organization & User Access Management Software

FusionAuth simplifies user management for complex structures such as B2B2C SaaS. Choose your approach and get secure, efficient control.

## Distinct User Identity

Model distinct user identities with tenants. [Tenants](/content/docs/get-started/core-concepts/tenants/index.html) are collections of users, applications and groups. Each has isolated configuration, including look and feel of the login screens, password requirements and email configuration. Users are identified by email or username and distinct and unique within a tenant. This approach is perfect for multi-tenant SaaS.

## Shared User Identity

Tenants logically separate system configuration and entities such as users or groups. Run only one FusionAuth instance, but keep your users, applications, API keys, and other objects separate and secure.

Manage users across organizations (like GitHub or Slack)

Control access for each team as needed

## Single-Tenant

FusionAuth gives you the best of both worlds: a secure, single-tenant architecture with the flexibility of multi-tenancy. Each FusionAuth instance operates on dedicated hardware, ensuring data isolation. Within your own instance, you can create and manage one or one million tenants.

[learn more](/content/docs/get-started/core-concepts/tenants/index.html)

## Scalable & Performant

Scale your application with FusionAuth. Create thousands of tenants or entities and manage tens of millions of users with ease. Our lightweight and searchable structures mean no built-in limits, providing you with the performance and flexibility needed for growth.

[Tenants Overview](/content/docs/get-started/core-concepts/tenants/index.html)

[Multi-tenant Guide](/content/docs/extend/examples/multi-tenant/index.html)

## Managing Tenants And Entities

FusionAuth’s admin UI, SDKs, and API let you choose how you want to manage tenants and entities. Bolster security by locking API keys to specific tenants, ensuring controlled access and easier operations. As your business needs change, FusionAuth is there to grow with you.

## Complete Auth for Any App

FusionAuth is a complete solution with no sacrifices. We got this. Go build something awesome.

**API Driven**\
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Use our customizable login flows or build your own experience on top of our APIs.\
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Explore Docs](/content/docs/lifecycle/authenticate-users/login-api/index.html) **Flexible Hosting**\
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Host yourself or use our cloud. It's always your data.\
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Learn More](/content/platform/self-hosting/index.html)

## Never Switch Customer Auth Providers Again

Whether you are building your MVP or have hit hockey stick growth, FusionAuth is a complete auth solution with no sacrifices. We got this. Go build something awesome.