Zero Egress.
Nothing you say ever leaves your phone.
Coming to iOS and Android. Not on the App Store or Google Play yet. The Android test build is available on request.
In training
Zero Theta: our own models.
ZERØ runs open models today, and says so on the download screen. Zero Theta is what we are fine-tuning next: a family shaped for this app in particular, for the way MiniShrink listens and the way Tutor works with you. There is no date. When there is something to show, it will be shown here.
Literally
There is no ZERØ server. There is no account. Your messages are typed into a model that is sitting on your own phone, and the answer is computed there. Nothing is uploaded, because there is nowhere to upload it to.
This website behaves the same way.
It is static HTML and CSS, and it runs no JavaScript at all. No trackers, no tag managers, no pixels, no embedded video, no fonts or images from anyone else's server, and nothing written to your browser. Loading this page makes your browser talk to our origin and to nobody else.
How it works
The app ships with no model in it. You pick one, it downloads from Hugging Face, and it is verified against an exact byte count and a SHA-256 before it is installed. After that it is a file on your phone.
About 2.5 GB for the default model. It resumes if it is interrupted.
llama.cpp loads the weights and generates the reply on the device's own processor.
Turn on airplane mode and it still answers. Nothing about a conversation needs a connection.
Downloading a file you asked for (the chat model, and optionally a small recall model), and opening findahelpline.com in your browser if you tap it on the Get help screen. Neither carries anything about your conversations. The library is not a download: it ships inside the app.
Modes
A mode is a set of instructions composed into every message, plus limits on how the model is sampled. Kid-safe is a container the others run inside, rather than a fifth behaviour.
General help, and the plainest of the four. It adds no instructions of its own, so your own system prompt is the only thing shaping it. It is told to say when it is unsure, never to invent facts or sources, and to answer in whatever language you write in.
Teaches step by step instead of handing over answers. Its first reply to a new question is always one short question back: what you already know, or what you have already tried. It holds that line however firmly you ask for the answer. Once you have shown it an attempt, the rule lifts and it helps properly. If you are genuinely stuck it gives it to you and then walks back through why it works.
How to Learn and Working in Maths are written for it. It may draw on at most one explanation in a turn, and only when you actually ask a question.
Tutor wears the Assistant skin, so there is no separate picture of it to show. What changes is what it says, not how it looks.
A locked container rather than a mode. You set an age band and a PIN, and inside it the app hides every screen except the chat.
The model, the downloads and the settings are locked, your own system prompt is ignored entirely, and leaving needs the PIN. The model is sampled colder than anywhere else in the app, because a small model drifts off its instructions when it is not, and the visible reasoning block is turned off, because it is confusing to a child and it leaks the model's working.
The instructions are written per band, not scaled by a parameter: one short sentence of five to eight words at two to four, a short paragraph that does not talk down at eleven to thirteen, near-adult answers with a few narrow absolute limits at seventeen.
Assistant, Tutor and MiniShrink all run inside it, with the container's rules composed on top. MiniShrink switches to a distinct child version rather than a softened adult one, and the only pack it can read is Big Feelings, the one written for children.
No violence, nothing sexual, nothing frightening, no drugs or weapons or self-harm, and not in a story, a joke or a "what if" either. A child saying a grown-up gave permission changes nothing. It will not claim to be a person, and it will not agree to keep a secret from a parent.
It is a child gate, not device security. Anyone who can unlock the phone can get around it, and the app says so.
A private place to think out loud. It listens, says back what it heard, and names the feeling tentatively so you can correct it. Advice is not its default and it is not allowed to slip in: it has to reflect first, then ask whether you want it to just listen or to work through something. If you say listen, it listens. If you ask it straight out for a suggestion, it gives one, in two or three sentences, then hands the floor back.
When you ask it to understand something, it may draw on a short explanation from the library that ships with the app: Understanding & Tools, Saying Hard Things, Deciding, Staying Private, What ZERO Is. At most one, only on a question, never as advice you did not request. Inside kid-safe it reads only Big Feelings.
It does not diagnose, does not use clinical labels about you, and does not comment on medication. If medication comes up at all, it says once that this is for your doctor or pharmacist, and goes back to listening. It will not tell you how to feel or rush you toward feeling better, and it will not pretend to be a person.
At the end of a session it writes three to six lines to itself and reads them before the next one. Those notes are on your phone. Deleting the conversation deletes them with it, and Settings has a button that deletes all of them at once.
A child gets the child version: gentler, simpler, no clinical words at all, and if something sounds genuinely serious it says clearly that a trusted grown-up needs to know. Those session notes can be read by whoever holds the PIN. The child is shown a standing line saying so, and the model is instructed never to call it a secret.
Before generating, a fixed check runs on your message. It needs first-person framing and an explicit object, so ordinary speech does not trip it. When it fires, the app takes over the opening line itself and points at the Get help screen. That screen makes no network call and runs no model.
What it isn't
What it is built on
ZERØ is not a model. It is an app around one. The model is Qwen 3: open weights under Apache 2.0, quantized to Q4_K_M and run through llama.cpp on the phone. The download screen tells you exactly which file it is fetching and from which repository, because someone about to pull 2.5 GB is entitled to know what it is.
One optional extra, downloaded once and then never fetched again. Recall is a 610 MB embedding model that lets MiniShrink find the notes that are about what you just said, rather than the three most recent ones. It is not required, and the app says what it does without it.
The library is eight packs that come with the app, not one, and they are not a download. They are tens of kilobytes each, already on the phone, because a download would be a request that says which explanations you went looking for. The assistant may draw on at most one explanation per turn, only on turns that actually ask a question, and each pack is only read in the modes it was written for. A pack can be switched off; switching it back on is instant because nothing was ever deleted.
Requirements
| Model | Quant | Download | RAM needed | Context |
|---|---|---|---|---|
| Qwen 3 4B Instruct (default) | Q4_K_M | 2.5 GB | 8 GB | 4096 |
| Qwen 3 1.7B Instruct | Q4_K_M | 1.1 GB | 6 GB | 4096 |
| Recall (optional) | Q8_0 | 610 MB | 6 GB | 1024 |
Quantization and context length are columns on a wider screen: Q4_K_M at 4096 tokens for both chat models, Q8_0 at 1024 for Recall.
Around 3 GB of free storage for the default model, iOS 16.4 or later, or Android 9 or later. The RAM floor is a hard gate, not a warning: a phone below it cannot download the model at all, and the app says why. On a 6 GB device, the 1.7B is the one that fits. The eight library packs come with the app and need no extra RAM.
Coming to iOS and Android. The Android test build is available on request. Ask on the Support page.