Articles/Privacy

On-device AI, explained: what leaves your phone and what does not

Updated 13 October 2026. 3 minute read.

"AI" on a phone can mean two very different things. In one case your text is sent over the internet to a large model in a data centre, processed there, and the result is sent back. In the other, a smaller model that is part of the operating system does the work on the phone itself. From the outside they look the same: you tap a button and a summary appears. For your privacy they are not the same at all.

Cloud AI

With a hosted model, the content you want processed has to travel to the provider. That means:

• The text leaves your device.
• It is handled under the provider's terms: how long it is kept, who can see it, whether it is used to improve the service.
• It needs a connection.
• Someone pays for the computing, which is why such features usually come with a subscription or a usage limit.

None of this is sinister. It is simply how it works. For a public news article it hardly matters. For a medical letter, a contract or a private note, it might.

On-device AI

Here the model is already on the device. On Apple devices that support Apple Intelligence, apps can use a language model built into the system.

• The text is processed in the device's own memory.
• Nothing is sent to the app's developer or to an AI company for that step.
• It works without a connection.
• There is no per-use cost, because your own chip does the work.

The trade-off is capability. A model that fits on a phone is smaller than one in a data centre. It is good at summarising, classifying and extracting, and less good at long reasoning or broad knowledge.

How to tell which one an app uses

• Read the privacy policy for the names of AI providers. If it lists one as a recipient of your content, processing happens there.
• Try it in Airplane Mode. A feature that still works offline is running locally.
• Look at the price. Unlimited AI features in a free app, with no account, are usually local.
• Check the App Store privacy label for what is collected.

What Stashy does

Stashy uses only Apple's on-device model. It has no hosted AI service and no server of its own. When you save something:

1. Your device fetches the page itself, the way a browser would.
2. The readable text is given to the system's language model on the device.
3. The model writes a short summary, picks a category from the ones you keep, and produces search keywords.
4. The results are stored with the item in your library.

Voice memos are transcribed with on-device speech recognition, and text in photos and scans is recognised locally as well.

What still uses the internet

On-device does not mean offline in every respect, and it is fair to be precise:

• Fetching a page means your device contacts that website, as it would in Safari.
• iCloud sync stores your library in your own iCloud. See where an app's iCloud data lives.
• Crash reports from the iPhone and iPad app are anonymous and contain none of your content.

The full list is in the privacy policy.

The short version

Ask one question of any AI feature: where does my text go? If the answer is "nowhere", you can use it on anything. If the answer is a company, decide case by case.