I have used many technologies to create back ends for various projects in many different areas.
My own app uses a custom back end using cron and PHP to deliver and transform images to where they need to be for the app to pick them up. This was an occasion when AWS seemed like overkill and would have incurred costs, the final solution was quite neat and free apart from hosting the scripts. Reliable too, haven’t needed to touch it for 5 years, it just keeps on going.
You can see it in action here, this loop shows actual rainfall radar for the UK taken and transformed from a weather site onto my own server.