A good start but needs a lot more work.

Text-only note taking — no images — is my biggest problem with this.

I’d really like to be able to take a screen grap, save it to a file and then import it into this app, but no.
I don’t even need them to be embedded in the text. There are already tabs for multiple files for a given
topic. File support for graphics is solidly built into Cocoa. So why not this feature is mystery to me.
Contacted the developer but this seems to be beyond his ability.

If you are ok with text only, then this is an ok app.

jeffsz about CodeBox, v1.6