About diagramkit

Made by someone who explains things for a living.

I’m Colin Matthews. I’ve taught more than 35,000 product managers, designers, engineers and operations professionals how AI systems work, and most of that teaching runs on diagrams. diagramkit is the tool I wanted for it: describe the idea, get a finished diagram you can publish.

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35,000+people taught how AI systems work

Lenny’s NewsletterHead of Education

30+team training and advisory engagements

1 AI productbuilt, launched and acquired

My students work at

Why diagramkit exists

When you explain how something works, the diagram does most of the work. A good one takes hours to make by hand. Image models are fast, but they misspell labels, invent arrows and can’t be fixed without starting over.

diagramkit started as the drawing engine behind interactive AI lessons I built. It became its own product in 2026: an AI that plans the diagram and an engine that lays it out, so the result is correct, finished and yours to edit.

A diagramkit diagram of retrieval-augmented generation: a question is embedded, matched to passages in a vector database, and answered by a language model using retrieved context and citations. — Made with diagramkit from “How retrieval-augmented generation answers a question”.

What I believe about diagrams

One idea per diagram.

A diagram that shows one thing clearly beats one that shows everything. diagramkit leaves things out on purpose, and you can always ask for more.

Real text, real lines.

Labels are text you can edit and lines are drawn by a layout engine, so nothing is misspelled, garbled or pointing at the wrong box.

Yours, not ours.

Your fonts, colours and visual style on every diagram, in the app, in Claude or ChatGPT, or through the API.

Questions or ideas? Get in touch, read Tech for Product or follow me on LinkedIn.