Two apps read your Mac at 3 AM. They disagree about what may leave it.

We make one of the two things on this page. Brownie is ours, and Sentient OS is the larger of the two by a wide margin — backed by Y Combinator, six hundred and ninety stars on GitHub against our four, and shipping since June while we started in September. Read this the way you would read any comparison written by the smaller party. Every claim about Sentient OS below is taken from its own README and site, checked on 2 November 2026. Where they have not published something, this page says that rather than guessing, and the one place their design is better than ours is marked as such.

This is not one of those comparisons where the products turn out to be unrelated. Both run on Apple silicon. Both ask for Full Disk Access and read the same local databases — Messages, WhatsApp, Apple Notes, Apple Mail. Both do the first pass with a model on your own GPU rather than uploading the raw material. Both write a knowledge base of ordinary Markdown files in your home folder that you own and can correct by hand. Both are AGPL-3.0. Both are free. Both wake a Mac that was asleep to do it.

So the interesting question is not which one reads your messages at night. They both do. It is what happens to what they find.

There is a relay, or there is no server. Sentient OS sends summaries, knowledge and task screenshots to whichever AI you chose, under your own account with that provider. Its Double Tap feature works differently: the screen under your pointer, your knowledge including your writing examples, and your instructions travel through Sentient's own relay to OpenAI, with Zero Data Retention, and you can point it at a local provider instead. Optional MCP sharing encrypts a folder with AES-256-GCM and uploads it to a relay that stores it without keeping the key. Brownie's summaries go from your Mac to your provider under your key, directly; there is no Brownie server in the middle, because there is no Brownie server.

There is a log, or there is not. Brownie keeps a screen called What left your Mac: every request, byte for byte, for thirty days, on your own disk. Not a count, not a category — the actual text that was sent, which you can read over breakfast and compare against what the app claims. Nothing in Sentient OS's documentation describes an equivalent. That is not an accusation of bad faith; it is the difference between a promise you accept and a promise you can check.

Running with nothing leaving is one setting, or three conditions. Sentient OS has a genuine offline mode, and it is honest about its requirements: local models for the main backend and for Double Tap, local sources, and cloud sharing switched off — all three, and browsing and sending email still need the internet. Brownie's version is a single choice called This Mac only, after which the reader doubles as the brain, no key is needed at all, and the number on the send log is zero.

Sensitive data is named, or it is not. Sentient OS filters “common sensitive identifiers” before summaries move on, and does not say which. Brownie drops anything the reader marks sensitive on sight — no note, no card, and no line in its own log containing it — with a second, rule-based check behind the model that catches the formats by shape: Aadhaar, PAN, passport, bank account with IFSC, Luhn-valid card numbers, US Social Security numbers. There are tests for each of them in the repository, and you can widen the definition in Settings → Privacy.

Sentient OS's documentation does not address most of the items above. That is not evidence against them — an unpublished detail is unpublished, not damning, and their privacy policy covers ground their README does not. It is the reason this page keeps saying described and documented rather than does and does not.

It handles a task it has never seen. Both of these drive your real applications — Brownie's Hands opens the app, finds the conversation and types, replaying by app link, accessibility tree or screen. The difference is that Hands replays something you showed it once, while Sidekick is handed a goal and works the steps out itself. For anything you do repeatedly that is a fair trade; the first time you want something done, Sidekick does it and Hands cannot yet.

And it presses the last button. Hands stops at Send, Pay and Delete, so Sentient OS will complete a task that Brownie leaves sitting there finished but unsent. If what you want is the thing gone, that is a real advantage and no argument about design philosophy changes it.

Double Tap and screenshots are good ideas we do not have. Pointing at something on screen and getting help with it, from an assistant that already knows your life, is a better interaction than anything in Brownie. Reading saved screenshots is a source we do not read at all.

Their Gmail design is better than ours, and this is the honest part. Sentient OS connects Gmail and Outlook through your own ChatGPT or Claude account, so you never grant a Sentient-hosted Google app access to your mail. Brownie signs into Google directly, which means Brownie is a registered OAuth application and you are granting it that access. Sentient's way is the better pattern and we should adopt it. While we are counting: usebrownie.com/oauth/slack is a page on this website that Slack redirects to during sign-in. It stores nothing and exists only to hand Slack's answer back to the app on your Mac — but it is a piece of our infrastructure in the path, and a page arguing that we have no server should say so.

And they have been read by people who are not us. Six hundred and ninety stars, sixty-five forks, a commit today, and a Y Combinator batch behind them. Brownie has four stars. Open source only means anything if somebody looks, and more people have looked at theirs.

When we compared Brownie with Apple Intelligence the answer was to run both, because an assistant you ask and a record that accumulates are different tools that happen to share a machine. That is not the case here. These two read the same databases on the same schedule and write competing Markdown knowledge bases into the same home folder. Running both means paying twice in battery and GPU time for two versions of the same notes.

Choose Sentient OS if you want the work finished. If the appeal of a personal AI is that it goes and does the thing — books it, sends it, fills the form in — then Sidekick is the product and Brownie's stopping rule will read as an obstacle rather than a safeguard.

Choose Brownie if you want to be able to check. No server in the path, a byte-for-byte log of everything that left, a one-click mode where nothing leaves at all, named rules for sensitive data with tests behind them, and no account that outlives the uninstall. If you are letting something read every message you have ever sent, being able to audit it tomorrow morning is the thing we built for.

The same question comes up in neighbouring categories, and we wrote those down too: local AI assistants for Mac, where nearly everything is a chat window you have to type into first; AI and Obsidian, where every plugin reads the vault and the registry has almost nothing that fills it; WhatsApp on a Mac; and what did I promise?, on closing a loop rather than logging one.

Read the log in the morning.