api-version

API versioning in Hono uses URL-based routing to manage multiple versions. Create versioned route files (v1, v2, v3) in your Hono app, mount each under its corresponding path (/v1, /v2), and handle endpoint changes within each version to maintain backward compatibility.

Migration patterns include gradual endpoint relocation, feature flags to toggle behavior, and explicit deprecation notices. Plan breaking changes in advance, document the migration path for clients, and ensure old endpoints remain functional during the transition period.

Backward compatibility requires preserving old endpoints in their original version while introducing new behavior in higher versions. Use deprecation markers to signal upcoming changes, provide clients with migration timelines, and avoid removing or altering request/response formats in existing versions.

Create a new version when making breaking changes—removing fields, altering response formats, or changing endpoint behavior. New versions let clients opt in to changes at their own pace while maintaining service for older clients still using previous versions.

Yes. Hono supports mounting multiple versioned routers in the same app under different paths (/v1, /v2, /v3). Each version handles its own routes and logic independently, allowing clients to call the version that matches their needs.