[alderz]

There is also https://github.com/yishn/tikzcd-editor which I have used a few times.

[cole-k]

It looks very similar to tikzcd-editor. Glad people are making tools like this -- I always felt so cool putting diagrams in my homework and tikzcd-editor was what allowed me to.

I'm sure the graders appreciated it, too, since my handwriting/drawing skills are lacking.