CORS middleware router.Use(cors.New(cors.Config{ AllowOrigins: []string{"https://foo.com"}, AllowMethods: []string{"PUT", "PATCH"}, AllowHeaders: []string{"Origin"}, ExposeHeaders: []string{"Content-Length"}, AllowCredentials: true, AllowOriginFunc: func(origin string) bool { return origin == "https://github.com" }, MaxAge: 12 * time.Hour, })).