Express MessagePack Middleware

express-msgpack is an Express middleware that provides transparent support for MessagePack (msgpack) content types, enabling developers to handle `application/msgpack` requests and responses using standard Express `req.body` and `res.json` patterns. It automatically decodes incoming MessagePack payloads into JavaScript objects and encodes outgoing JavaScript objects into MessagePack format when clients request it via the `Accept` header. The current stable version is 6.0.0, which mandates Node.js 20.12.0 or higher. The package is actively maintained with releases frequently aligned with Node.js version updates and new features such as `allowUnacceptableResponse` and `limit` options. A key differentiator is its seamless integration with existing Express API patterns, which reduces boilerplate, and the flexibility to utilize custom MessagePack encoder/decoder libraries.