cloudflare has a js runtime that is similar to node, but different, and closely follows Web Workers API. It has a great free tier and is really cheap to run (cheaper than lambda, but similar idea of light backend single-purpose functions.) CF also has a pretty good history of respecting privacy, and resisting censorship, especially over AWS and heroku.

Is there interest in porting the backend service to CF workers? If so, I can PR for it.