[RadiozRadioz]

It's telling that almost all these comments recommend things that aren't JavaScript web frameworks. This has been my experience too, you want to avoid that ecosystem. For this reason in particular:

> language/platform/dependencies updates are infrequent, easy to do, unlikely to break the app;

I'll second the Django, Rails, Laravel, but also add something statically typed like Java with Spring if this is purely an API backend. Static types will give you peace of mind during runtime for years.

Stick to relational databases. Don't buy into hype stuff on Medium blogs. You can go a long way on a VPS with an LTS distro on auto-update (very few SaaS businesses actually have scale that exceeds what a modern VPS can do).