Kemal Crystal

require "base64"
require "kemal"

GIF = Base64.decode("R0lGODlhAQABAIAAAP///wAAACH5BAEAAAAALAAAAAABAAEAAAICRAEAOw==")

get "/pixel.gif" do |env|
  env.response.content_type = "image/gif"
  env.response.headers["Cache-Control"] = "no-store"
  env.response.write(GIF) # write the bytes; a non-String return value is ignored
  nil
end

Kemal.run(8080)