There’s a category of note app now that does something new. You dump thoughts in all week, and later you ask a plain-language question (“what did I decide about the lease?”) and it answers, grounded in what you actually wrote, pointing at the exact note. Not keyword search. An answer with a source.
Almost all of them do it the same way: your notes go to a server, a large model reads them there, and the answer comes back. That’s the part worth slowing down on. The trick works because your private notes are sitting on someone else’s computer, in readable form, at the moment you ask.
Second Brain does the same trick: ask your notes, get a cited answer, hear an honest “I don’t know” when nothing is saved. The difference is that the search and model run on your iPhone or iPad. There is no Studio AM account or AI-processing server. Notes remain local unless you enable optional private iCloud sync, which is off by default and inaccessible to Studio AM. This is a fair look at how the main options handle your data, because you can check the design yourself: the AI works in airplane mode.
Where each app actually sends your notes
I looked up the current data handling for each. Two of these are local-first like us, and I’ll say so plainly.
| App | Where your notes live | Where the AI runs | Account | Cited “ask my notes”? |
|---|---|---|---|---|
| Second Brain | On device by default; optional private iCloud sync | Your iPhone or iPad (on-device AI model) | No | Yes, built in |
| Apple Notes | Your device (iCloud sync) | On-device for some tasks; heavier ones use Apple’s Private Cloud Compute servers | Apple ID | No grounded, cited Q&A |
| Obsidian | Local markdown files | Fully local with Ollama, or a cloud model if you add one | No (local) | Only if you build it |
| Reflect | End-to-end encrypted, then synced | Highlighted text (or matching notes, for chat) sent to a cloud model | Yes | Yes (cloud) |
| Notion AI | Notion’s servers | Notion’s servers | Yes | Yes (cloud) |
| Mem | Mem’s servers | Mem’s servers | Yes | Yes (cloud) |
| Saner.ai | Saner’s servers | cloud model servers | Yes | Yes (cloud, cross-source) |
A few notes on that table:
- Reflect has the best privacy story of the cloud tools. Your notes are end-to-end encrypted, and text you highlight (and, for its notes chat, the notes matching your question) is sent to a cloud model. But the AI itself runs in the cloud; to answer, that text leaves your device. Credit where it’s due; it’s a thoughtful design.
- Notion, Mem, and Saner are cloud-first by design, and they’re good at it: cross-platform, team features, and in Saner’s case a useful sweep across your email, calendar, and Slack. The trade with all three is simply where the work happens: your text is processed on their servers to answer.
- Apple Notes and Obsidian are local-first, same as us. I won’t pretend otherwise. Obsidian is plain markdown on your own disk; wire up Ollama and its AI is fully local too. Apple Notes keeps your notes on-device. The catch is the AI: Apple’s heavier tasks route to Private Cloud Compute (Apple’s servers), and neither ships a grounded, cited “ask everything I ever saved” out of the box. Obsidian can do it, but you assemble it yourself from plugins.
What “on-device” buys you, concretely
Second Brain’s whole ask-your-notes feature runs on an on-device model: the retrieval that finds the right notes, and the answer written from them. In practice that means:
- It works on a plane. Offline is the default, not a degraded fallback.
- There’s no account to create and no server log with your name on it. We can’t read your notes, because we never receive them.
- The citations are the honesty check. Every answer points at the note it came from, and when nothing’s saved it says so instead of inventing. A small on-device model earns trust by staying pinned to your own words, not by being clever.
The cost: it runs only on iPhone and iPad today, on iOS or iPadOS 26. Apple Intelligence devices use Apple’s built-in model; other supported devices may need a one-time on-device model download before the AI can work offline. Notion and Obsidian, by contrast, run almost everywhere. If your notes live across five devices and a shared team space, a cloud tool may fit you better. That is a trade, and I would rather you make it with eyes open. Second Brain has no functional free plan. Eligible new subscribers may receive a 3-day trial, followed by $4.99 a month or $29.99 a year in the US. Without an active subscription, previously saved notes remain readable and searchable, saved recordings remain playable, and note and Ask text remains exportable.
Which one fits you
If your notes are meeting agendas and shared docs, cloud AI is fine, often better. But if your notes are the stuff you would never post (the half-formed, the personal, the things you are still working out), there is a meaningful difference between cloud inference and a design where the AI processing stays on your own hardware.
Second Brain is that second thing: a note app that answers questions from your own notes, private and offline, with citations you can check. You can see exactly how it works, and grab it if it’s out, on its app page. The best thing we can do with your most personal notes is never hold them.
Frequently asked questions
Can an AI note app answer questions without uploading my notes?
Yes. Second Brain runs retrieval and answer generation on your iPhone or iPad, cites the notes it used, and works offline. Notes stay local unless you enable optional private iCloud sync, which Studio AM cannot read.
Does Second Brain require a free or paid account?
It requires no Studio AM account and has no functional free plan. Eligible new subscribers may receive a 3-day trial, followed by $4.99 per month or $29.99 per year in the US.
What happens to my notes if the subscription ends?
Previously saved notes remain readable and searchable, recordings remain playable, note and Ask text remain exportable, and existing items remain deletable.
Does a Second Brain export include voice recordings?
No. Markdown and JSON exports contain note and Ask text, not recording audio, so they are portable text records rather than complete backups.
For a direct feature comparison, see Second Brain vs Apple Notes vs Obsidian. For the cloud-workspace trade-off, see Notion AI vs a private on-device second brain.