You need to export the User.name field so that the json package can see it. Rename the name field to Name.
package main
import (
"fmt"
"encoding/json"
)
type User struct {
Name string
}
func main() {
user := &User{Name: "Frank"}
b, err := json.Marshal(user)
if err != nil {
fmt.Println(err)
return
}
fmt.Println(string(b))
}
Output:
{"Name":"Frank"}