I’d like to have my own server at home sorta like a home AWS.
How to set up one and make it available to anyone over the Internet? What tech specs should I buy (RAM, CPU, # of cores, operating system, etc.)?
How much does it cost to keep one running all the time?
make it available to anyone
To do what?
Generally speaking, not a well-advised idea, especially for someone who has to ask how to do it (truly not being snarky).
I was a cisco instructor in the 90’s, (so teaching networking and security were my bread and butter for a while) and I wouldn’t think of doing this - except… If the only access was via a mesh network client such as Tails/Tailscale, the server was dedicated to just this purpose, it was isolated on its own LAN segment/DMZ with no routing path to my home network segment, the server was not Windows, but Linux, and I had a robust backup plan, access control plan, and access monitoring with alerts.
There’s just too much risk exposing a port to the world.
If you’re only accessing the server remotely via Tailscale and no ports are open, is it necessary to have the server on its own isolated VLAN? I like accessing my server locally most of the time and via Tailscale when I’m out and about.
That’s a REALLY broad definition.
A web app that does what?
Are you running your own Netflix-ish server? Transaction processing? Cloud storage? Ai chatbot?
Each one has very different requirements, and this is just the first four that came to mind .
AWS has hundreds of buildings filled with millions of servers, so you aren’t going to compete with that, even on a small scale.
But could you run your own little Facebook type thing? For a handful of users, sure. Could you handle the number of users that Facebook actually has in a day? You are looking at buildings filled with Computers, not a single machine’s spec 
You can host most basic web apps off a raspberry pi. You just need to:
- connect your device to the internet
- start your server application
- set up port forwarding on your router to forward the port your application is being hosted on
- get a domain name
- configure ddns
- Maybe get some SSL certs
.
Edit: BearOfaTime brings up a great point. I’m telling you how to do what you asked but you probably shouldn’t. If you do, try to airgap the server from your personal network as best as you can
Edit edit: You know people will let you use their servers for small projects for free right? Check out https://ctrl-c.club/#what or hang out in the LowEndTalk forums and provide quality input and enter some of the giveaways for server space
Although the drawback to ctrl-c club is that you’re not going to get full control of how you install libraries and applications
