Why We Built Stubble to Run Entirely on Your Mac
Cloud AI is convenient. Local AI is private. Here's why we chose to process everything on-device—and what that means for you.
When we started building Stubble, we had a choice: use cloud APIs for AI processing, or build everything to run locally on your Mac.
Cloud would have been easier. Faster to ship. Cheaper to build. But it would have meant your screen data—every document, every conversation, every tab—flowing through our servers.
We chose local.
The Privacy Problem with Cloud AI
Most AI-powered productivity tools work like this: they capture your data, send it to a server, process it with a large language model, and send results back.
This creates several problems:
You don’t control your data. Once it leaves your device, you’re trusting the company’s security, their policies, their employees, and every third-party vendor they use.
Screenshots are especially sensitive. A screenshot can contain passwords, financial data, personal conversations, medical information—anything visible on your screen at that moment.
Compliance becomes complex. If you work with client data, sending screenshots to a third-party cloud may violate your agreements—even if that cloud is “secure.”
How Local AI Works
Stubble runs entirely on your Mac using Apple Silicon’s neural engine. Here’s what that means:
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Screen capture stays local. Screenshots are taken, processed, and deleted on your device. They’re never uploaded anywhere.
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AI inference runs on-device. We use optimized models that run efficiently on M1/M2/M3 chips. No API calls, no network requests.
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Your data is your data. We literally cannot access your screen content. There’s no server receiving it, no database storing it, no employee who could view it.
The Tradeoffs
Local AI isn’t free. The models are smaller than cloud giants like GPT-4. Processing uses your CPU and memory. Some advanced features are harder to implement.
But for time tracking—where the AI needs to understand “what app is this” and “what project is this”—local models are more than capable. And the privacy benefits are absolute.
What This Means for You
When you use Stubble:
- Your IT team doesn’t need to approve a new cloud vendor
- Your client data never leaves your machine
- You don’t need to trust our security—there’s nothing to secure
- If we went out of business tomorrow, your data would still be yours
Privacy isn’t a feature we added. It’s how we built the product.