Starting with v3.0.0, when decoding MessagePack Timestamp into Go’s time.Time, the default Location will be UTC (previously Local). The instant is unchanged. To keep the old behavior, use SetDecodedTimeAsLocal().

• Supported types : primitive / array / slice / struct / map / interface{} and time.Time
• Renaming fields via msgpack:"field_name"
• Omitting fields via msgpack:"-"
• Omitting empty fields via msgpack:"field_name,omitempty"
• Supports extend encoder / decoder (example)
• Can also Encoding / Decoding struct as array

Current version is msgpack/v2.

go get -u github.com/shamaton/msgpack/v2

package main
import (
  "github.com/shamaton/msgpack/v2"
  "net/http"
)
type Struct struct {
	String string
}
// simple
func main() {
	v := Struct{String: "msgpack"}
	d, err := msgpack.Marshal(v)
	if err != nil {
		panic(err)
	}
	r := Struct{}
	if err =  msgpack.Unmarshal(d, &r); err != nil {
		panic(err)
	}
}
// streaming
func handle(w http.ResponseWriter, r *http.Request) {
	var body Struct
	if err := msgpack.UnmarshalRead(r, &body); err != nil {
		panic(err)
    }
	if err := msgpack.MarshalWrite(w, body); err != nil {
		panic(err)
    }
}

TL;DR: Starting with v3.0.0, when decoding MessagePack Timestamp into Go’s time.Time, the default Location will be UTC (previously Local). The instant is unchanged—only the display/location changes. This avoids host-dependent differences and aligns with common distributed systems practice.

• Before (v2.x): Decoded time.Time defaults to Local.
• After (v3.0.0): Decoded time.Time defaults to UTC.

MessagePack’s Timestamp encodes an instant (epoch seconds + nanoseconds) and does not carry timezone info. Your data’s point in time is the same; only time.Time.Location() differs.

• Eliminate environment-dependent behavior (e.g., different hosts showing different local zones).
• Make “UTC by default” the safe, predictable baseline for logs, APIs, and distributed apps.

• Apps that display local time without explicitly converting from UTC.
• If your code already normalizes to UTC or explicitly sets a location, you’re likely unaffected.

If you want the v2 behavior on v3:

msgpack.SetDecodedTimeAsLocal()

Or convert after the fact:

var t time.Time
_ = msgpack.Unmarshal(data, &t)
t = t.In(time.Local)

You can opt into UTC today on v2.x:

msgpack.SetDecodedTimeAsUTC()

This result made from shamaton/msgpack_bench

This library is under the MIT License.