> For the complete documentation index, see [llms.txt](/docs/llms.txt)

# FusionAuth Documentation | FusionAuth Docs

Learn what FusionAuth is and how to get started using it.

# FusionAuth Documentation

FusionAuth is a Customer Identity and Access Management (CIAM) server that provides:

*   Authentication
*   Authorization
*   User Management

```mermaid
graph LR
	classDef orangeBorder stroke:#ff9800,stroke-width:2px;
    User -->|authenticates| FA(FusionAuth):::orangeBorder
    App -->|delegates auth| FA
    
    FA <-->|brokers identity| IdP[External IdPs]

    User(("<div class='flex flex-col items-center text-sm dark:text-white text-slate-800'><svg width='16' height='16' viewBox='0 0 640 640'><path style='fill: currentColor !important' d='M320 312c66.3 0 120-53.7 120-120S386.3 72 320 72s-120 53.7-120 120s53.7 120 120 120m-29.7 56C191.8 368 112 447.8 112 546.3c0 16.4 13.3 29.7 29.7 29.7h356.6c16.4 0 29.7-13.3 29.7-29.7c0-98.5-79.8-178.3-178.3-178.3z' /></svg>User</div>")) -->|consumes| App[Application]
```

FusionAuth connects users, applications, and identity providers

FusionAuth provides a full implementation of [OAuth2](/docs/lifecycle/authenticate-users/oauth), [OpenID Connect (OIDC)](/docs/lifecycle/authenticate-users/identity-providers/overview-oidc), and [SAML v2](/docs/lifecycle/authenticate-users/saml), where FusionAuth functions as both a [Service Provider (SP)](/docs/lifecycle/authenticate-users/identity-providers/overview-samlv2) and a [SAML Identity Provider (IdP)](/docs/lifecycle/authenticate-users/saml#configure-fusionauth-as-a-saml-identity-provider).

## Try[#](#try)

To get started with FusionAuth today, check out one of our [quickstarts](/docs/get-started/quickstarts/).

[React](/docs/get-started/quickstarts/spa/react)[Django](/docs/get-started/quickstarts/web/quickstart-python-django-web)[iOS](/docs/get-started/quickstarts/app/quickstart-swift-ios-native)[Go](/docs/get-started/quickstarts/api/quickstart-golang-api)

## Deploy[#](#deploy)

You can deploy FusionAuth anywhere: self-hosted on a [local machine](/docs/get-started/download-and-install/docker), on-premises in [your own cloud](/docs/get-started/run-in-the-cloud/marketplaces), on an [air-gapped server](/docs/get-started/download-and-install/reference/air-gapping), or via a [managed FusionAuth Cloud instance](/docs/get-started/run-in-the-cloud/cloud).

[Self-Host](/docs/get-started/download-and-install/docker)[Cloud Marketplace](/docs/get-started/run-in-the-cloud/marketplaces)[FusionAuth Cloud](/pricing?step=plan&hosting=basic-cloud)

## Customization[#](#customization)

FusionAuth is highly customizable, both in appearance and behavior. You can control every [page](/docs/customize/look-and-feel/simple-theme-editor) and [message](/docs/customize/email-and-messages/message-templates-replacement-variables). You can use lambda functions to customize [data validation](/docs/extend/code/lambdas/login-validation), [MFA challenge logic](/docs/extend/code/lambdas/mfa-requirement), [token transformation](/docs/extend/code/lambdas/jwt-populate), and [much more](/docs/extend/code/lambdas). You can use webhooks to [react to a wide variety of events](/docs/extend/events-and-webhooks/events).

[Theme](/docs/customize/look-and-feel/simple-theme-editor)[Messages](/docs/customize/email-and-messages/message-templates-replacement-variables)[Lambdas](/docs/extend/code/lambdas)

## Authentication Protocols[#](#authentication-protocols)

FusionAuth supports most popular authentication protocols, including username/password, [a wide range of identity providers](/docs/lifecycle/authenticate-users/identity-providers), [passkeys](/docs/lifecycle/authenticate-users/passwordless/webauthn-passkeys), and [passwordless logic like magic links and OTP](/docs/lifecycle/authenticate-users/passwordless).

[Identity Providers](/docs/lifecycle/authenticate-users/identity-providers)[Social Sign-On](/docs/lifecycle/authenticate-users/identity-providers/#social-identity-providers)[Enterprise Sign-On](/docs/lifecycle/authenticate-users/identity-providers/#enterprise-identity-providers)[Passkeys](/docs/lifecycle/authenticate-users/passwordless/webauthn-passkeys)[Passwordless](/docs/lifecycle/authenticate-users/passwordless)

## Authorization[#](#authorization)

Define permissions using role-based access control (RBAC) with [users](/docs/get-started/core-concepts/users), [roles](/docs/get-started/core-concepts/roles), [groups](/docs/get-started/core-concepts/groups), [applications](/docs/get-started/core-concepts/applications), and [entities](/docs/get-started/core-concepts/entity-management). For highly granular permissions, check out our [fine-grained authorization](/docs/extend/fine-grained-authorization) integration.

[Role-Based Access Control (RBAC)](/docs/get-started/core-concepts/roles)[Fine-Grained Authorization (FGA)](/docs/extend/fine-grained-authorization)

## Security[#](#security)

Configure threat mitigation and detection features like [multi-factor authentication (MFA)](/docs/lifecycle/authenticate-users/multi-factor-authentication), [breached password detection](/docs/operate/secure/breached-password-detection), [rate limiting](/docs/operate/secure/advanced-threat-detection#customizable-rate-limiting), and [captcha](/docs/operate/secure/advanced-threat-detection#captcha) to keep both you and your users secure.

[Multi-Factor Authentication (MFA)](/docs/lifecycle/authenticate-users/multi-factor-authentication)[Captcha](/docs/operate/secure/advanced-threat-detection#captcha)[Rate Limiting](/docs/operate/secure/advanced-threat-detection#customizable-rate-limiting)

## Support[#](#support)

When you can't figure out how to solve a problem yourself, FusionAuth provides [first-class support](/docs/operate/troubleshooting/technical-support) from battle-hardened humans.