Diagrams as code
Write a few objects in Diagon's compact diagram language on the left; the diagram draws and lays itself out live on the right.
Desktop app · Windows / Linux · macOS soon
Diagrams that are code.
Write a few objects on the left, watch the diagram lay itself out on the right — then drag any node and its position is written straight back into your code. Both directions. Always in sync.
30-day free trial · €4.99/month or €49.90/year · cancel anytime
01The loop
round-trip
The loop
Write
a few objects in Diagon's compact diagram language.
Watch
the layout engine draw and arrange the diagram live.
Drag
any node — its position lands back in your code.
Ask
your own AI assistant, once connected, to draw or change the diagram.
02What makes it Diagon
4 capabilities
What makes it Diagon
Drag writes code
Grab any node with the mouse and its position is written straight back into your code. The source stays the single source of truth — both ways.
Its own layout engine
A custom layered auto-layout engine built for this language — no external diagram libraries, no browser-tab feel. A real desktop app.
Works with your AI assistant
Diagon has no AI of its own. Connect an assistant that runs on the same computer — Claude Code or Claude Desktop, Cursor, Copilot in VS Code, Codex — and it can read the diagram you have open and draw or change it in your window. A chat in a web browser can't connect. Off until you switch it on; what the assistant reads goes to its own provider.
03See it move
the loop, recorded
See it move
Demo video
Being recorded.
04How buying works
How buying works
Try free. Subscribe when it earns its keep.
Every feature is free for 30 days — no account, no card. Then a subscription keeps the whole app unlocked — €4.99 a month, or €49.90 a year with two months free. Cancel anytime; when it ends, Diagon locks until you renew, and your diagrams — plain-text files — stay yours either way. Checkout, invoicing and VAT are handled by FastSpring, our merchant of record.
- Windows
- Linux
- macOS · soon
05Questions
4 answers
Questions, answered
- How does the trial work?
- Every feature, free for 30 days from first launch — no account, no card. After that, a subscription key — entered once — keeps the app unlocked.
- What does the subscription include?
- The full app and every update while it's active — €4.99 monthly, or €49.90 yearly (two months free). It renews itself with a tiny licence check when you're online; cancel anytime in FastSpring's portal, or from the subscription link in your receipt. When it ends, Diagon locks until you renew — your diagrams are plain-text files and stay yours either way.
- Does Diagon send my data anywhere?
- Not your diagrams. Diagon has no telemetry and no AI of its own, and it never uploads what you draw. It reaches the network for three small things, none of which carries diagram text: a licence check that sends your licence key and nothing else, update checks and downloads from GitHub, and any icon URL in a diagram, fetched from the host it names. If you connect your own AI assistant, what it reads from the open diagram is sent by that assistant to its own provider, under your agreement with them — never to us. That connection is off until you switch it on.
- Which platforms?
- Windows and Linux (AppImage + deb) today — each download is about 100–130 MB. The macOS build is on its way.