Most AI app builders run in a browser tab. Your project lives on their servers, their AI edits it there, and you download it, or don't, at the end. It is an easy way to start, and for many people it is the right one.
K2Coder works the other way round. It is a Mac app, your project is a folder on your disk, and the AI works on that folder where it sits. This month we reviewed that choice properly, against the alternative of moving every build into the cloud, and kept it. This post explains why.
What stays on your Mac
Your project. It is an ordinary folder, in git, that you can open in any editor, copy, zip or delete. K2Coder never uploads it to us. When you deploy a site, it goes from your Mac to the host you chose, with your own account there.
Your AI keys. If you use your own Gemini, OpenAI, DeepSeek or Kimi key, it lives in your Mac's Keychain and goes from your Mac to that provider. It is never stored on our servers.
Your history. Chats, checkpoints and the project's notes about its own decisions are saved on your Mac, next to the project or in K2Coder's own folder.
What uses our cloud, and why
One thing: Quantum Cloud credit, for people who would rather not get their own AI keys. When you pay with credit, requests go through our service so that we can check your balance, set aside the cost and charge you exactly what each request used. That service records what it needs to bill you (which model, how many tokens, how long it took). It does not store your prompts or the model's answers.
Why not run every build in the cloud?
We costed it seriously. Running each build in its own cloud machine has a real advantage: a build carries on when you close your laptop. Three things outweighed it.
Your code would have to leave your computer by default. Today it never does unless you deploy it. We did not want to change that promise for everyone to give some people a convenience.
The cost lands on you. Machines that sit ready for builds cost money every hour whether anyone is building or not. A tool that runs on the computer you already own does not need to recover that.
A problem in a shared system reaches everyone in it. A mistake on your own Mac affects your own Mac. We would rather keep it that way.
What this means in practice
- K2Coder works without our servers. With your own keys, or with a model running on your Mac, it does not need us at all.
- You can leave whenever you like. Your projects are plain folders and your keys are your own. There is nothing to export because nothing was ever locked in.
- Builds run while K2Coder is open. Close the app and the build stops. If running builds in the cloud ever makes sense for the people using K2Coder, it will be something you switch on per task, with the cost shown first, not the default.
K2Coder is free to download for Mac at quantumaccordbg.com/k2coder.