How it works
Syntropium is built from a small number of ideas. Once you have these, you have the whole app.
Containers and items
Everything in Syntropium is a thing, and a thing either opens or it doesn’t.
- A container is a thing that opens: it can hold other things. A room, the garage, a storage unit, a cabinet, a shelf, a drawer, a toolbox, a tote, a jar.
- An item is a thing that doesn’t open: the object you want to find later. It has a name, and can have a description, a quantity, tags, a photo, and an estimate of what it is worth.
Containers can hold items and other containers, nested as deeply as your storage really is. There are no fixed levels and no categories to set up first. If you start with “Garage” and later realise the garage has three shelving units, add them inside it and move things onto them.
Every thing has exactly one place: the container it sits in, or the top level. That gives every item a path, such as House › Hall closet › Top shelf › Shoebox › Spare keys. The path is the answer to “where is it?”.
Counts are counts of things, not quantities. A box holding “Screws ×200” and a drill holds two items, not 201.
The map
The app is a single screen arranged like a cutaway drawing of your storage. On a computer you see three parts side by side; on a phone you see one at a time and move between them.
- The tree lists your containers from the top level down, so you can see the shape of everything at a glance and open any branch.
- The bench shows what is inside the container you have open, as cards, with how much each container holds.
- The inspector shows the details of the one thing you have selected: its name, description, quantity, tags, photo and path, where you can edit them.
Each level inward is drawn a little warmer, so you can feel how deep you are without reading the path.
Search
Search looks through names, descriptions and tags, ignoring capitals. Each result shows its full path, so a match tells you not only what but where. Tags are free-form words you choose — “winter”, “camping”, “borrowed” — and can be put on any thing, including containers.
Moving things by carrying them
To move something, you pick it up and carry it, the way you would in real life. Select one thing or several, choose Carry, then open the container where they should go and put them down. On a computer you can also drag and drop.
Syntropium won’t let you put a container inside itself, or inside something it contains. When you delete a container that still holds things, it asks where its contents should go first, so nothing disappears by accident.
Undo
Every change — adding, editing, moving, deleting — goes into one history. Undo steps back through it, one change at a time. A short message after each change tells you what happened and offers Undo right there.
Photos stay on your device
You can add a photo to any thing, on the free version or with Premium. Photos are kept on the device you took them on, alongside your catalog. They are not uploaded anywhere unless you turn on Premium sync, and then only encrypted.
Using the web app on iPhone or iPad? Safari may clear a website’s stored data if you don’t visit it for a while. To keep your catalog and photos safe, add Syntropium to your Home Screen, and export a backup from time to time. The iPhone app is not affected.
Backups you can take with you
From Settings you can export a complete backup at any time. When your catalog has photos, the backup is a single .zip file holding the catalog and every photo; otherwise it is a small .json file. You can import a backup on any device to restore it.
Without Premium, a backup is the only copy of your catalog that isn’t on your device — so it is worth making one now and then, and keeping it somewhere safe.
Free and Premium
| Free | Premium | |
|---|---|---|
| Containers, items, search, carry, undo | Yes | Yes |
| Photos | Yes, on this device | Yes, on all your devices |
| Works offline | Yes | Yes; changes sync when you’re back online |
| Export and import backups | Yes | Yes |
| Account needed | No | Yes, signed in with a passkey |
| Sync between devices | No | Yes, end-to-end encrypted |
| Price | Free | not yet set (free for beta testers) |
How sync works: passkeys and pairing
Premium keeps your catalog and its photos in step across your iPhone, your computer and any other browser you use. Change something on one, and the others catch up the next time they connect. Each device keeps its own full copy, so everything still works without a connection.
Encrypted before it leaves
Before anything is sent, your device encrypts it with a key that only your devices hold. Our server stores and relays the encrypted result. It cannot read your catalog or see how it is organised. The details are on Privacy & trust.
Passkeys, not passwords
You sign in with a passkey: the same Face ID, Touch ID, fingerprint or device PIN you already use to unlock your phone or computer. There is no password and no email address to type. The same passkey also unlocks your encryption key, so one prompt does both.
Adding a device by pairing
To add another device, start from one that is already syncing. It shows a QR code; scan it with the new device (or open the link it gives you). The two devices agree on the new device’s access between themselves, and the new device creates its own passkey. No password is typed and our server never sees your key. If your passkey is already shared between your devices through iCloud Keychain or Google Password Manager, a new browser can simply turn on syncing with it.
Seeing and removing devices
Settings lists the devices on your account. Removing one cuts it off: it can no longer sync or fetch anything from your account. Whatever is already stored on that device stays there, as it would with any app — so if a device is lost, remove it from another one.