FastAPI is fully compatible with (and based on) Starlette. So, any additional Starlette code you have, will also work.FastAPI is actually a sub-class of Starlette. So, if you already know or use Starlette, most of the functionality will work the same way.

With FastAPI you get all of Starlette's features (as FastAPI is just Starlette on steroids):

Further info:FastAPI is a thin wrapper around Starlette, making creating an additional integration for Starlette along the way possibly trivial

Building an integration for Starlette is possibly trivial while we are already doing so for FastAPI

• Wrap ASGI Middleware
• Exeption Handling
• RequestExtractor
• Starlette Middleware Spans
• Auth/User Info