Built by people who love a good, simple diagram.

SimpleDiagrams began as a friendly desktop app to help you explain things. Some people found it cool. Some people made nice diagrams.

But then it died.

Or rather, the platform it was built on died. Then there was silence across the land. And some made diagrams with other tools, but those diagrams looked dumb and everyone knew it.

But now it's back...

The dark time of dumb, boring diagrams has passed. SimpleDiagrams is back as two separate products: SimpleDiagrams Desktop and SimpleDiagrams Cloud.

For the desktop, we're releasing a new MacOS version, with the same basic UI you know and love. (Linux and Windows versions may follow later, we'll see.)

For the web, we're releasing a new web application based on the most excellent Excalidraw open source library, which is much cooler than anything we could produce. The focus for the web version is on dynamic diagrams you can update in real time via API or MCP.

( Unfortunately SimpleDiagrams Desktop and SimpleDiagrams Cloud don't yet interoperate, so buying or subscribing to one does not provide access to the other. But we're working on that... )

What SimpleDiagrams does

SimpleDiagrams Cloud combines a clear visual canvas with simple shapes and connections, then adds tools that give the diagram a live state. Authors describe the system once; trusted people, APIs, and agents can then keep the diagram view current.

Who made this monstrosity

SimpleDiagrams is made by McQuillen Interactive, a small, independent software studio in Melbourne, Australia. We've built tools for research, building performance, education, and teams doing serious work with complex systems.

...and we make tools for stupid simple diagrams.

Who it is for

Anyone who wants to communicate visually with a simple diagram.

Who it's not for

People who are doing critical things that need 100% reliability and up-time, like running nuclear power plants or ambulance fleets or greedy stock trading systems. SimpleDiagrams Cloud is only for informal diagrams and non-critical systems. (See the SimpleDiagrams Cloud Terms for more info.)

How we work

We are a small studio, and we intend to keep SimpleD easy and fun even as we add new features. We value simplicty in all things. We like working closely with early customers (contact us, please). We'll add complex features when the app needs it, but we'll have a good think before we do.