Vercel + Go

package main

import (
    "encoding/json"
    "net/http"
    "os"
)

func main() {
    mux := http.NewServeMux()

    mux.HandleFunc("/", func(w http.ResponseWriter, r *http.Request) {
        json.NewEncoder(w).Encode(map[string]string{
            "message": "Go on Vercel!",
        })
    })

    port := os.Getenv("PORT")
    http.ListenAndServe(":"+port, mux)
}