JSON file? More like hard coded conditionals in the code.
Code? I hand-craft every HTTP response myself
Cute. I personally deliver IP packets directly to the customers' front router.
While you're doing that like a remote corporate asshole, I'm in the room speed sketching screen refreshes for them so they don't need to even waste power on running a computer.
I walk to each customer site and use telnet for the HTTP requests.
JSON documents can easily live in the DB ;)
You're not looking at it right. The JSON document is your DB. Wanna add another client config? Your client manager makes a PR with the changes and your CI deploys it with the server binary. Easy peasy no-code solution.
If you have CI, that's still over-engineered for a pre-mvp product.
Just kidding... partially
I think CI is actually one that you should do when you write your first few lines of code. GitHub actions is free, comes with one click templates, so use it.