Frequently asked questions

Everything about NianTou in one place: what it is, how it differs from a notes app, how the encryption actually works, what the servers can read, which AI features send text out, which platforms are supported, and how to export or delete your data. The answers aim to be specific rather than reassuring.

About the product

What is NianTou?

NianTou is a strictly private journal for fleeting thoughts, also known as The Archive of Mind. It holds the things that arrive and vanish within minutes — an insight, a pang, a worry, a sudden recognition. You capture one in a line of text or a voice note; each entry is time-stamped to the minute and kept permanently. It is built to set feelings down, not to organise information.

Why the name?

NianTou (念头) means "a thought" — the thing being recorded. The Archive of Mind describes what the app does with it: rather than scattering notes, it binds a person's thoughts and moods across periods so a stretch of life can be read back as a whole. One name points at the content, the other at the form.

How is it different from a notes app?

Notes apps organise information and implicitly expect sharing: folders, collaboration, retrieval speed. NianTou is built around a single assumption — that what you write is for you alone. There is no share button, no public feed and no social graph, and entries are encrypted on your device before upload. It holds moods and moments rather than tasks and reference material.

Who is it for?

Four uses come up most: catching ideas before they evaporate; seeing the shape of your own mood over time; writing to a future self and comparing the same subject across years; and setting down things you would not say aloud or put anywhere public. The app assumes nothing about who you are — only that some thoughts have nowhere else to go.

Do I need an account?

Yes. You can sign in with a phone number and SMS code, or with WeChat. Account data consists only of a login identifier and a password hash, used to sync your content across devices. It contains no readable entry text.

Privacy and encryption

Is my content private? Can anyone else read it?

Entries are encrypted on your device before they are uploaded, and the servers store ciphertext that cannot be turned back into your words. There is no feed, no followers and no audience, so there is no product path by which a stranger could come across your entries. An app lock and a PIN add a further barrier if someone picks up your device.

How does the encryption work, and where is the key?

Encryption happens on your device. The key is generated there and stays there — it is never uploaded alongside your content. The server holds ciphertext and has no decryption key.

That has a consequence worth stating plainly: if the key is lost, we cannot recover your entries. Clearing app data, or reinstalling without keeping the key, means the ciphertext on the server can never be unlocked. Any product claiming both end-to-end encryption and the ability to restore your plaintext for you is not telling the truth about one of the two.

What can the servers read, and what can they not read?

This is the part that most deserves to be spelled out, so it is split in two:

See the privacy policy for the full statement and encryption and data boundaries for the technical detail.

Can I recover my entries on a new phone?

Yes, provided you sign in with the same account and that account's key is still available. Entries sync to the server as ciphertext and are decrypted on the device by the local key. If the key has already been lost, the ciphertext cannot be unlocked and we cannot restore it for you.

Can I export my data?

Yes. The app exports every entry that can be decrypted on this device as JSON, and states how many were left out if some were encrypted with a different device's key. Exported data is plain text, so store it carefully. Voice audio is not included in the JSON export.

After I delete an entry, is it really gone?

Deleting removes it from your device and from the cloud list immediately, and after syncing it no longer appears on your other devices. To keep devices consistent, the server keeps a deletion marker containing no text. You can also clear all local data on a device, which deletes the entire local database and cannot be undone.

AI features and data boundaries

Where does my content go when I use AI features?

Some AI features need a language model to read your text, so at that step end-to-end encryption cannot hold. What is sent, by feature:

Text travels over HTTPS to our servers and is passed to the model provider — Alibaba Cloud Bailian (Alibaba Group, located in mainland China) — using the qwen-plus model. We do not write your text to our database or to access logs; internal task logs record only the task type, success, token count and elapsed time. We cannot make commitments on the model provider's own retention policy.

Can I use NianTou without the AI features?

Recording, the timeline, monthly archives, tag search, year-over-year comparison and the mood curve all read locally encrypted data and do not depend on AI. But one thing must be stated plainly: automatic tagging on save is the default behaviour of the current version, and there is no setting to disable it — each save sends that entry for tagging. If you need nothing to leave the device, do not use the AI-dependent features.

Can AI output replace therapy?

No. AI-generated content is language the model produces from your own text — a way of surfacing patterns for self-reflection. It is not diagnosis, therapeutic advice or crisis intervention, and the in-app insights carry that disclaimer.

Platforms and using it

Which platforms are supported?

The web app runs in any browser with nothing to install, and there is an Android client with a smoother voice-recording experience. An iOS app is in development and has not been released, so no iOS version is available at this time.

Are voice recordings uploaded?

No. Voice notes recorded by holding the button stay on your device and are never uploaded. The current version has no speech-to-text service connected, so no audio is sent anywhere for processing.

Does it cost anything?

Core journaling and archiving are free. Deeper capabilities — AI deep insight and fuller mood analysis — unlock through in-app purchase. There is no advertising and no sale of data.

Which languages are available?

Simplified Chinese and English.

How do I get started?

Open citta.fyi and choose to start — the journal opens directly in your browser. A three-screen introduction covers recording, settling a thought and privacy, after which you can write your first entry.

Limits and where to get help

Is NianTou a medical service?

No. It does not provide diagnosis, therapy or crisis intervention. The self-assessment scales (PHQ-9, GAD-7 and a short personality exploration) are self-reflection references only; they are not a medical assessment and cannot replace professional evaluation.

What if I am in crisis right now?

Please do not rely on any journaling app to handle a crisis. If you are having thoughts of harming yourself, or you are in danger, contact your local emergency services or a crisis helpline, or go to the nearest emergency department. The support page lists available services.

What is it not?

Not a social platform — no follows, likes or feed; you will not see anyone else's entries and they will not see yours. Not a task manager — no to-dos, reminders or collaboration. And not a promise of absolute security: no software can promise that nothing will ever go wrong, so protect your device and your account as well.

Still have a question?

Read encryption and data boundaries for the technical detail, or the full privacy policy. If that does not settle it, write to support@citta.fyi or see the support page.