# OpenAPI / Swagger UI
Generate interactive Swagger UI pages from OpenAPI specifications.
## Single API
```json
{
"openapi": "swagger.json"
}
```
This generates a Swagger UI page at `api-docs.html`.
## Multiple APIs
```json
{
"openapi": {
"api-docs": "swagger/v1.json",
"admin-api": "swagger/admin.json"
}
}
```
Each key becomes a separate HTML page (e.g., `api-docs.html`, `admin-api.html`).
## Specification Format
Both JSON and YAML OpenAPI specifications are supported. The spec file path is relative to the book's root directory.