If you have ever looked for a way to leave a message for someone after you die, you will have met the phrase "dead man's switch". The idea is simple enough to explain in one line: keep checking in, and nothing happens. Stop checking in, and your messages are sent.
It is simple because it makes one assumption. That silence means death.
For most of what a switch like that is used for, the assumption is harmless. If it releases a password file a week late, or a fortnight early, nobody is hurt. But the things people actually want to leave behind are rarely passwords. They are letters to a child. An explanation. An apology. The practical instructions only you know. And for those, being early is not a small error. It is the whole failure.
What silence actually means
People stop replying for reasons that have nothing to do with dying. A stay in hospital. A phone left in a taxi. A week somewhere with no signal. A stretch of depression where opening an app is more than you can manage. A change of number that never reached the service.
Any system built on silence has to pick a number of days and hope. Too short and it fires on a holiday. Too long and it is not much of a safeguard. There is no number that is right, because the system is measuring the wrong thing.
The question Y.O.D.O. asks instead
Y.O.D.O. treats a missed Check-in as the beginning of a conversation, not the end of one.
You confirm you are well on your own rhythm. Miss one, and you have a Response Window of eight hours before anything else happens, with reminders inside it. After that, people you chose yourself are asked. Not told. Your Delegates are people who know you, and the first thing they can do is say the thing a machine cannot: that you are fine, you are in hospital, you are away.
You decide when they are contacted. Eight, sixteen, twenty-four or forty-eight hours after your check-in time, set by you in advance. If someone raises a concern, everyone else involved has seventy-two hours to respond before anything is settled, so one person's worry is never the whole story.
And if there is a reason you will be out of reach, a Delegate can request a Care Pause and stop check-ins for fifteen or thirty days without anything escalating at all.
Before anything is released
Reporting a passing is a deliberate act, not a timer running out. It requires identity verification through Persona, a death certificate, and a review by a person at Y.O.D.O.
That last part is worth being precise about, because it is easy to claim and hard to build. Even when Delegates agree, and even when every window has expired, a passing report cannot reach a verified state without a human reviewer. We do not make automated decisions with legal or similarly significant effects, and that is built into the system rather than written on a policy page.
Once a passing is verified, Recipients are notified and have twelve months to read what was left for them. If a Recipient is under eighteen, they do not simply receive it: a guardian has to provide evidence and be approved before access is given.
The honest part
Y.O.D.O. is new. We were incorporated in the United Kingdom as company 15736034 and the service went live this year. If you are choosing something to hold a letter for twenty years, that is a fair thing to weigh, and we would rather say it than have you find it.
What we can offer instead of a long history is a short one you can inspect. Our policies are published, including a data protection impact assessment. Our verification process is written down in detail rather than described in a sentence. We keep an Article 27 representative in the EU. The service runs in twenty-five languages, because the people who need it are not all in one country.
And here is advice that costs us something to give: whichever service you choose, including ours, keep a second copy of anything that truly matters somewhere offline. A company can have good intentions and still have an outage, or close. Anyone who tells you their service is the only copy you need is selling you something.
How to choose, whoever you choose
If you are comparing services, the useful question is not which has the nicest interface. It is this: what has to be true before my message is sent?
If the answer is "you stopped replying", you know what you are buying, and for some purposes that is genuinely enough. If the answer involves a person you trust being asked, a window in which someone can say wait, and a check that a death actually occurred, you are buying something different.
Y.O.D.O. is built for the second kind. Not because the first is careless, but because some letters should only ever arrive once, and only when they are true.