> ## Documentation Index
> Fetch the complete documentation index at: https://docs.fga.dev/llms.txt
> Use this file to discover all available pages before exploring further.

# Welcome to Auth0 Fine-Grained Authorization

> Model relationships, write authorization data, and check access with Auth0 FGA.

# Welcome to Auth0 Fine-Grained Authorization

Auth0 Fine-Grained Authorization enables developers to design authorization models, from coarse-grained to
fine-grained, in a way that is centralized, flexible, fast, scalable, and easy to use.

[Learn more
](/fga)

Model relationships between users and resources, then ask Auth0 FGA whether access should be allowed.

![A relationship graph connecting users, groups, resources, and permissions in Auth0 FGA.](https://mintlify.s3.us-west-1.amazonaws.com/auth0-fga/images/landing/home-banner-diagram.png)

## Authorization for your app in 3 steps

Auth0 FGA is a fully hosted, managed service with no infrastructure for you to deploy or operate.

### Define your authorization model

Learn to define an authorization model with step-by-step guides and examples.

[Get started ](/modeling)

[
Modeling basics](/modeling/basics/modeling-basics)

[
Modeling user groups](/modeling/basics/user-groups)

[
Modeling roles and permissions](/modeling/basics/roles-and-permissions)

[
More modeling guides](/modeling)

### Write your authorization data

Learn to programmatically write authorization data to Auth0 FGA.

[Overview ](/writing-data)

[
User access](/writing-data/managing-user-access)

[
Group membership](/writing-data/managing-group-membership)

[
Relationships between objects](/writing-data/managing-relationships-between-objects)

[
Transactional writes](/writing-data/transactional-writes)

### Add authorization to your API

Update your API to check a user's permissions before allowing an action.

[Overview ](/integration)

[01.
Get your API keys](/integration/getting-your-api-keys)

[02.
Install the SDK](/integration/install-sdk)

[03.
Update relationship tuples](/integration/update-tuples)

[04.
Perform a check](/integration/perform-check)

[05.
Integrate with your framework](/integration)

## Advanced features

Modeling

### Advanced modeling

Learn how real-world authorization use cases can be modeled with Auth0 FGA.

[Modeling samples
](/modeling/advanced#use-cases)

[Advanced patterns
](/modeling/advanced#patterns)

Reference

### API documentation

Use the Auth0 FGA API to programmatically manage authorization and answer access questions.

[Explore the API
](/api/service)