Free, in full.
The simulator, the canvas, every component and unlimited private projects — no account, no trial, no feature held back to sell you later.
Free Available now
No account. No card. Not a trial.
- The full circuit canvas and every component
- Real AVR simulation and the analog solver
- Code editor, serial monitor and plotter
- Unlimited private projects, stored locally
- All nine worked examples
- Offline desktop app for macOS, Windows and Linux
.cdlimport and export — your circuits stay yours
Signed desktop build Free meanwhile
$10 minimum · one payment, no subscription, no account.
- Notarised and code-signed binaries
- Updates that install themselves on macOS and Windows
- Everything in Free — this buys convenience, not features
Payment isn't set up yet, so the builds are simply free to download in the meantime.
Go to downloadsPro Planned — not yet available
Nothing to buy today. There is no checkout and no account system; this is published so the funding model isn't a surprise later.
- Unlimited cloud projects with version history
- Priority compile lane
- Private share links and embeds
- GIF export
- Free for students, teachers, and anyone with a merged pull request
What stays free, permanently
Private projects are free, forever. Local projects are private by construction — they are files on your disk. There is no plan in which your work has to be public to avoid paying.
Local AI stays free and unmetered. Point the assistant at Ollama, LM Studio or llama.cpp and nothing is counted. Only hosted inference would ever be billed, because only hosted inference costs anything to run.
Self-hosting is free. Run your own compile service and your own backend and you owe nothing — see the docs.
Questions worth answering plainly
If it's open source, what would I be paying for?
The things that cost money to provide: an Apple Developer ID, Windows code-signing, notarisation, and servers that compile and store things on your behalf. The source is Apache-2.0 and buildable — there is no licence check and nothing is withheld from a build you make yourself. Paying funds the project; it is not how you get access.
Why publish a price for something I can't buy?
Because the alternative is a tool that looks free forever and then grows a paywall. The intended shape is on this page before it exists, so you can decide now whether it's a project you want to depend on.
Will the free tier get worse when Pro arrives?
Squeezing the free tier is the standard way to hit conversion targets, and it is exactly what makes tools unpleasant to build on. The list above is what free means: local simulation, all components, unlimited private projects. Pro is for things that run on someone else's computer.
What about the compile service?
The browser can't run arduino-cli, so editing a sketch and
pressing Run in the browser calls a small hosted service. That service
is the one feature that costs real money per use, which is why it is
the first candidate for a paid lane. The desktop app compiles locally
and needs none of it.