How Lutum works

Your data can't be read without your key

Neither Lutum nor its servers can read what is in your data. This page explains how.

Locked before it is stored

Your device locks the data before sending it to the server. Only your devices hold the key, so the server cannot read the contents. It works like leaving a locked box at a warehouse.

Your device

Holds the key

Lutum's server

Stores locked boxes

Your other device

Opens boxes if you gave it the key

How syncing works

1. Make a change
You edit your data on a device.
2. Lock and send
Your device locks the change, then sends it to the server.
3. Store in order
The server stores each box in the order it arrives. When several devices write at once, the server picks a single order.
4. Open on another device
Your other device picks up the boxes, opens them with its own key, and applies them in the same order.

Where your data lives

This device

Data kept on this device. It is not sent to the server and not synced. Until you turn on sync, all of your data is here.

Synced data

Data that is locked and shared between your own devices through the server. Syncing is a paid plan feature.

Scratch space for apps

Data an app uses temporarily, such as input fields. Each device has its own copy, and it is not shared with other devices. It can be lost without harm.

Your key

Your key is made on your device and is never given to the server. This has some consequences.

To use a new device, show a QR code on a device you already use and pass the key across.
Save your recovery key in a password manager or another safe place. It lets you get your key back even if you lose every device.
If you lose every device and the recovery key, Lutum cannot restore your key either, and synced data can no longer be opened. Signing in does not bring a lost key back.

Other notes

You can still view data saved on your device while offline. Writing synced data needs an internet connection.
When you ask the AI something, the content needed for that question is sent to the AI service you set up. This page covers the data Lutum stores on its servers.

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