Guide
The best private AI for your Mac in 2027: what to look for
Updated 29 October 2026 · 6 min read
The best private AI for your Mac is one that runs on your Mac, works without the internet, never trains on your data, and tells you exactly what it sends. In 2027 that's finally possible: the Macs people already own can run capable AI models on their own chips. This guide gives you eight checks to tell a truly private AI apart from a cloud chatbot with a privacy page.
The eight checks
- It runs on your Mac, not on someone else's server.
- It works offline.
- It never trains on your data, in writing.
- It encrypts what it keeps, with keys on your device.
- It tells you exactly what it sends, and when.
- It asks before reading your mail, notes or files.
- It fits your Mac without slowing it down.
- It's honest about its limits and shows its sources.
1. It runs on your Mac
"Private" means very different things. Most AI assistants send every message to a data centre, where it's processed, logged and often kept. A truly private AI processes your words on your own computer, so there's nothing to leak from a server because nothing reaches one.
The test: turn off Wi-Fi and ask it a question. If it still answers, the thinking happens on your Mac.
2. It works offline
Running on your Mac is half of it. The other half is knowing things without looking them up online. Good private AI comes with offline knowledge, such as an encyclopedia, reference guides or maps data, so it stays useful on a plane, in the mountains, or when the network is down.
3. It never trains on your data, in writing
Look for a plain sentence in the privacy policy saying your conversations are never used to train models. With an AI that runs on your Mac, this should be easy to promise, because the company never receives your conversations at all.
4. It encrypts what it keeps
Your chat history is a diary. It should be encrypted on your disk, with the key kept in your Mac's Keychain on that device only. Also turn on FileVault (System Settings › Privacy & Security) so your whole disk is protected if your Mac is lost.
5. It tells you exactly what it sends
Even an on-device AI goes online sometimes, for example to download a model or an update. A trustworthy one lists every case: what is sent, to whom, and why. If a company can't tell you in one short page, treat that as your answer.
6. It asks before reading your life
The most useful private AI can read your notes, mail and calendar to actually help. That should be off until you switch it on, one source at a time, with macOS asking for your permission. It should also treat what it reads as information, never as instructions, so a malicious email can't take it over (a risk called prompt injection).
7. It fits your Mac
AI models live in your Mac's memory (RAM). A good private AI picks a model your Mac can run comfortably and never takes the memory your other apps need. Roughly:
| Your Mac's memory | What to expect |
|---|---|
| 8 GB | A small, fast model for everyday help: writing, summaries, quick questions. |
| 16 GB | A capable everyday assistant (around 4 billion parameters) with room left for your other apps. |
| 24 GB and more | Larger, more careful models, and longer documents at once. |
Fanless laptops like the MacBook Air can warm up during long sessions. Look for an app that slows down or pauses to keep your Mac cool instead of pushing it.
8. It's honest about its limits
A model small enough for a laptop knows less about the world than the biggest cloud models. That's a fair trade for privacy, but only if the AI is honest about it: it should say "I don't know" instead of guessing, show which source it used, and never invent numbers such as medicine doses. Ask it something it can't know, like the exact population of your town on a specific date, and see whether it makes something up.
How Sublunar fits
We build Sublunar, so take this section as ours, not neutral. Glim, Sublunar's AI, runs on your Mac and works offline with a built-in library (Wikipedia, first aid, repair guides and every town on Earth). Your chats are encrypted on your disk with a Keychain key on that Mac only, and the app sends no analytics. Your notes, mail and calendar stay off until you switch them on. Our Security page lists exactly what the app sends, and our research log shows what our tests caught, including the failures. Sublunar is in private beta.
Common questions
Can AI run on a Mac without the internet?
Yes. Apple-silicon Macs can run AI models on their own chips. With an app that includes offline knowledge, the AI keeps working with Wi-Fi off.
Is a cloud chatbot private?
Your messages are processed on the provider's servers, and depending on the service and your settings they may be stored, reviewed or used to improve models. Check each provider's policy. With an AI that runs on your Mac, your messages never leave it.
How much memory do I need for AI on a Mac?
8 GB runs small, fast models. 16 GB is comfortable for a capable everyday assistant. More memory allows larger models and longer documents.
Is on-device AI as smart as cloud AI?
Not for everything. The biggest cloud models know more about the world. But for your own life, your notes, mail, calendar and files, a private AI can help with things you'd never paste into a chatbot. A simple rule: keep cloud AI for the world, and a private AI for your life.
Written by the Sublunar team. Questions or corrections: hello@sublunar.ai. Join the Sublunar beta.