Go standard library Go

package main

import (
	"encoding/base64"
	"log"
	"os"
)

func main() {
	gif, err := base64.StdEncoding.DecodeString("R0lGODlhAQABAIAAAP///wAAACH5BAEAAAAALAAAAAABAAEAAAICRAEAOw==")
	if err != nil {
		log.Fatal(err)
	}
	if err := os.WriteFile("pixel.gif", gif, 0o644); err != nil {
		log.Fatal(err)
	}
}