Know where everything you own is.

What it is

Syntropium has one idea at its centre: containers hold things. A container is anything that holds something else — a room, a garage, a storage unit, a shelf, a drawer, a tote, a jar. An item is the thing you want to find later — a drill, a passport, the spare charger, a box of canning lids.

Containers can hold items, and they can hold other containers, as deep as your real storage goes. So the answer to “where is it?” is always a path you can follow with your feet:

Garage › Shelf 2 › Blue tote › Organizer A › Wood screws

It works in a web browser on any computer or phone, open to everyone, free. The iPhone app is in beta, by invitation.

Why it exists

Syntropium started with a practical problem: a farm, a workshop and a house, each full of tools, parts, supplies and keepsakes, spread across buildings, shelves and boxes. Things were bought twice because the first one couldn’t be found. Time went into looking instead of doing. Spreadsheets didn’t survive contact with real life, and most inventory apps were built for warehouses, not for the way a household actually keeps things.

What was missing was something simple: write down where a thing went, the moment it goes there, and be able to ask later. Without an account to set up, without a subscription to read your own list, and without handing a complete record of everything you own to someone else’s server.

The name comes from syntropy, the opposite of entropy. Left alone, a house drifts toward disorder; every move, every project, every “I’ll put it here for now” adds a little more. Syntropium doesn’t pretend you will ever be finished. It helps you add order a little at a time — which is what the mantra means: Growing order from chaos…

The core ideas

• One kind of thing

  There are no categories to design up front. A container is just a thing that opens; an item is a thing that doesn’t. Start with one room and grow from there.

• Find it in seconds

  Search by name, description or tag. Every result shows its full path, so you know which shelf, which tote and which box.

• Your catalog lives with you

  Everything you enter is kept on your own device. It works without a connection, and you can export a complete backup — including photos — whenever you like.

• Sync that we can’t read

  Premium keeps your catalog and photos in step across your devices. It is end-to-end encrypted on your devices before it leaves them; our server stores only what it cannot read.

• No passwords

  Syncing uses passkeys — your phone’s or computer’s own Face ID, Touch ID or PIN. There is no password to forget, reuse or leak.

• Honest about the trade-offs

  Because nobody but you holds the key, nobody can recover synced data for you if you lose every device. We say so plainly, and we tell you how to protect yourself. See Privacy & trust.

Try it

The web app is ready to use now. Open it, make your first container, and put an item in it — a short walkthrough shows you the rest. Nothing to install and no account needed; what you enter stays in that browser.

The iPhone app is in beta. Syntropium is in an invited beta. Beta testers get Premium sync free while they help us find what’s confusing. Read about the beta.