axum-impl-openapi

Use utoipa-axum's OpenApiRouter with the routes! macro to register annotated Axum handlers once, generating OpenAPI 3 specs and routing simultaneously to eliminate drift between your actual endpoints and documentation.

Yes, you can serve an interactive Swagger UI from an Axum service by merging utoipa-swagger-ui's SwaggerUi component with your generated OpenAPI JSON endpoint, provided the swagger-ui crate has the required axum feature enabled.

Yes, you must explicitly pin the three independently-versioned crates (utoipa, utoipa-axum, and utoipa-swagger-ui) to compatible versions, as mismatched crate versions across Axum differences can cause compilation or runtime issues.

utoipa uses derive macros and handler annotations like #[utoipa::path] with {param} on your actual Rust types to automatically generate OpenAPI 3 request and response schemas that reflect your real Axum endpoint structures.

OpenAPI specs drift from Axum routes when documentation is maintained separately from routing logic; using utoipa-axum's OpenApiRouter registers each handler once to derive both routing and spec output consistently, preventing synchronization issues.

The best way to document Axum REST endpoints is using utoipa derive macros with OpenApiRouter to automatically generate OpenAPI 3 specifications and an interactive Swagger UI explorer from your actual Rust handler and schema types.