What's your favorite way of getting a web app up quickly in 2020?

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.