Play Framework Scala

// conf/routes:
// GET     /pixel.gif     controllers.PixelController.pixel

// app/controllers/PixelController.scala
package controllers

import javax.inject.*
import play.api.mvc.*

@Singleton
class PixelController @Inject() (cc: ControllerComponents) extends AbstractController(cc):
  private val gif = java.util.Base64.getDecoder.decode("R0lGODlhAQABAIAAAP///wAAACH5BAEAAAAALAAAAAABAAEAAAICRAEAOw==")

  def pixel: Action[AnyContent] = Action {
    Ok(gif).as("image/gif").withHeaders(CACHE_CONTROL -> "no-store")
  }