#### Check the `openapi.json`

If you are curious about how the raw OpenAPI schema looks like, FastAPI automatically generates a JSON (schema) with the descriptions of all your API.

!!! warning
    You can probably skip this.

    These are very technical details of how **FastAPI** works underneath.

    If you have quite some technical knowledge (coroutines, threads, blocking, etc.) and are curious about how FastAPI handles `async def` vs normal `def`, go ahead.

### Path operation functions

    In many cases, OAuth2 with scopes can be an overkill.

    But if you know you need it, or you are curious, keep reading.

## OAuth2 scopes and OpenAPI

The OAuth2 specification defines "scopes" as a list of strings separated by spaces.

The content of each of these strings can have any format, but should not contain spaces.

Because of that, it's now recommended to instead use the `lifespan` as explained above.

## Technical Details

Just a technical detail for the curious nerds. 🤓

!!! note "Very Technical Details"
    If you are curious and have a deep technical knowledge, you can check the very technical details of how this `async def` vs `def` is handled in the [Async](../async.md#very-technical-details){.internal-link target=_blank} docs.

## Migrations