I'm using Sinatra - little overhead, simple code. I used node.js/express.js in the past, but the callback hell made me dislike it a bit, although admittedly I'm

I'm using Sinatra - little overhead, simple code. I used node.js/express.js in the past, but the callback hell made me dislike it a bit, although admittedly I'm not experienced with node, so there might be a way to avoid that. I had a look at Firebase and my main problem with it is having to rely on 3rd party service and storing data on their servers + portability if I was to decide to leave them in the future.