I am still frustrated with the amount of incidental complexity required whenever I want to do this. My latest attempt was to use a Digital Ocean droplet with Django pre-installed. I guess the biggest issue there was setting up something so that I could easily deploy my local version to the droplet (ended up using git/Github), and ensuring those two environments were in sync. I looked into Docker in some detail about a year ago, and I think it's the only pretty good solution for this I've come across—but there's a steep up front cost in learning/setup etc. (or so it seems).
What services and technologies do you use when you'd like to quickly build a web app which may never be more than a prototype, but may also turn into something real? A big aspect of what I'm wondering is about automatically setting something up for keeping local/production environments in sync, quickly deploying to production, and not having to mess with a bunch of server configuration things, user accounts, security, etc.
Everyone else here is trying to be stylish and fancy.
Your customers don't care what language it's in or whether the code is beautiful.
No cutting edge incomplete frameworks, convoluted tooling, piles of inaccurate documentation to read, inexplicable cryptic error messages with a bunch of incorrect solutions on stack overflow, or other incompetently over engineered bullshit.
Just go as vanilla, basic, and standard as possible.
True speed comes when you don't have to deal with other people's bugs and poorly designed mistakes.
Don't rely on code written by flocks of people you'd never hire in a million years.