About

Four days

In September 2024 one of my two Bengal cats did not come home. He was gone for four days. On the fourth afternoon the cat flap rattled, he walked in, went to his bowl, and ate as if nothing had happened. He never told me where he had been, and that is how it works with animals.

What I did during those four days was look for something that would have told me.

What I found while he was gone

What I found were GPS trackers: too big for a cat’s neck, a few days on a charge, and around ten euros a month for a service you hope never to use. I bought two to try. Both disappointed. And the moment a cat sits inside a shed or under a floor, GPS has nothing to work with at all.

That is where the distinction landed. Tracking is following: continuous, and paid for in battery, in money, and in a detailed record of where your animal has been. Finding is something else. Finding happens at the moment you need it, and the rest of the time the device can sleep.

I was not looking for a better tracker. I was looking for a finder.

The design brief

Five things had to be true, or it was not worth building. They still decide every choice we make.

It has to find, not follow. Continuous reporting means a continuous record of where your animal has been. We did not want to hold that, and your cat does not need it.

It has to work where cats actually go. Sheds, crawl spaces, under a car, deep in a hedge. GPS needs a clear view of the sky, so it gives up exactly where a cat is hardest to find. Long-range radio does not.

It has to last weeks, not days. A finder you have to charge every other day is a finder that is off the collar half the time.

It has to cost almost nothing to run. Keeping a cat findable should not need a second phone contract.

It has to be worth leaving on. 36 x 26 x 10 mm, and made to look like something you put on an animal on purpose. A cat wears it day and night, so it should read as an accessory, not as a gadget.

If you want a tracker, buy a tracker

Do you want to see where your cat is every second of the day? That is interesting for about a week. If that is what you are after, buy a tracker. They are good at it, and we are not trying to be.

Onimo does something else. It quietly learns where your cat normally spends her time and shows you that as a territory map, so you know her patterns without watching her live. And when she is genuinely missing, it uses everything it has: the long-range LoRa link to your Finder that reaches through walls and floors, Bluetooth for the last few metres, a passive WiFi scan to place her indoors, and GPS as the backup that only wakes when it is needed.

Bluetooth tags are a category of their own, and for keys or a suitcase they usually work. On a cat they run into three walls. They are not built to survive a life in rain and mud on a collar. Their range is around thirty metres in the open and far less through a wall, and they are only found when someone else’s phone happens to walk past. And they are made for finding something near you, not for an animal that may be three streets away in a shed where nobody goes. That is a different problem, and it needs different radio.

Weeks, not days

The Onimo S sleeps. Every so often it wakes for a fraction of a second, asks your Finder one question, am I being looked for, and goes back to sleep. That is the whole reason a battery this small lasts this long, and you set the rhythm yourself: once a minute, once every two minutes, or once every five. More often and you find faster, less often and the battery lasts longer.

The trade-off is honest in both directions. When you start a search, the Onimo S only hears about it at its next check-in, so the wait is never longer than the interval you chose. From that moment it stops saving power and puts everything it has into being found.

What we built

The Onimo S sits on the collar and stays quiet. The Onimo F, the Finder, sits in your home and does the finding. Cats come first for a practical reason: a cat that goes missing is usually still close to home, well within range of its own Finder.

Where we stand

Most companies treat privacy as a feature, something that can be switched off later. We treat it as infrastructure: part of how the thing is built, not a promise we can withdraw. Where your cat goes is yours. We do not sell it and we do not share it. The full position, including where the promise stops, is at onimo.org.

Onimo is a Dutch company, founded by Paul Marcus after twenty-five years inside large organisations. Someone had to build this one.