Implementing Role-Based Access Control (RBAC) in a FastAPI application is crucial for ensuring users have appropriate access levels based on predefined roles. This tutorial guides you through creating a secure contact management app using FastAPI, with a detailed authorization layer integrated through Permit.io, an authorization-as-a-service provider. The application allows administrators full access to manage contacts and user roles, while regular users can only manage their contacts. It utilizes a tech stack comprising FastAPI, Uvicorn, PostgreSQL, SQLAlchemy, and Alembic, with the project structure set up to include authentication and user role management capabilities. The tutorial covers setting up user roles and permissions on the Permit dashboard and integrating this with the FastAPI app to enforce role-based permissions. It highlights the use of utility functions to sync users with Permit, enforce permissions, and protect privileged actions, ensuring that only authorized users can perform specific tasks. The guide concludes by emphasizing the app's scalability and readiness for real-world use, with further resources available for deeper exploration of Permit.io's capabilities.