Thing is, 99% of the code I'm proud of and want to show off are my own projects which I've put a lot of time into, and are profitable SaaS apps. Not enough to negate a day job, but enough to afford life without one. I have a lot of free time and I found a company I'm very excited to join that is very in line with what I am doing.
I'm not against sending them code, and it's not that I don't trust them, I am just trying to find the best way to go about this without sending all the code to a fully working and profitable SaaS app.
However, I would not share a full non-open source working code, less so if it belongs to my side job. Send some part of it with some of it "redacted" if they really need to see your code skills, talk about the architecture with them, show them the evolution of the platform (the issues you found and the like).
I would personally never share more than some small snippets of code. Throw those snippets on a different repo and that’s it.
If they demand to see more of the code base, ask them specifically what they’d like. If they want the entire project, I wouldn’t proceed any further.
I have done interviews where the initial stages were vague, and they couldn’t go into any more detail until you had signed the NDA.
IMO, that’s normal for interviewing for a position at a company or a group inside of a company that has not yet launched their product, or is otherwise doing sensitive stuff.
Just a few representative branches and snippets, here and there.