[glawre]

I like the C4 Model as a guide on the different levels of abstraction that you might need for your system.

[NomDePlum]

Second this.

Reference for anyone looking I to it: https://c4model.com/

There is also quite a lot of options for helping create these diagrams. I've found https://structurizr.com/ to be the best of what I've tried so far.

[Onawa]

I like the idea behind structurizr, but I found the syntax to be too constraining and the tooling around it to be difficult to deal with. That was 2 years ago though,maybe I should revisit it.

[jasonpeacock]

Third this. Don't look any further, just do it!

Also, PlantUML + C4 is like peanut butter & jelly:

https://github.com/plantuml-stdlib/C4-PlantUML

I'll gladly give up control of layout, and accept some ugliness, to never again have to worry about dragging boxes and arrows to be pixel-aligned, and then do it all over again when I add another box...

It looks like Mermaid has C4 support too:

https://mermaid.js.org/syntax/c4.html

[pinkmuffinere]

Oh thanks, this looks like the kind of thing I was searching for — will read up on it