What is a dead man's switch for crypto?

A mechanism as old as locomotives, rebuilt in smart-contract form: as long as you keep signaling "I'm here," nothing happens. When the signals stop, your crypto goes to the person you chose. Here's exactly how it works — and the hard questions to ask anyone selling you one.

By the Will & Key team · Updated August 2026

The train driver's handle

Early locomotives had a simple safety problem: what if the driver dies at the controls? The answer was a handle the driver had to keep holding. Grip it and the train runs; let go and the brakes apply. The system doesn't need to know the driver is dead — absence of the signal is the signal.

That inversion is what makes the idea perfect for crypto inheritance, because it solves the problem no blockchain can solve directly: a smart contract cannot check a death certificate. It can, however, notice that an address which used to send a heartbeat transaction every month has gone silent for a year.

The mechanism, step by step

1. Lock. You put funds in a vault contract and name your heir's wallet address. You choose an inactivity period — how long the silence must last.
2. Check in. Any time before the period elapses, you send a cheap transaction that resets the timer. Checking in monthly on a 90-day timer means three missed months before anything can happen.
3. Claim. If the timer truly runs out, your heir — and only the wallet you named — can initiate a claim.
4. Challenge window. The claim doesn't settle instantly. A veto period runs (in Will & Key's case, minimum seven days, typically 30) during which any action from your wallet cancels the claim and resets everything. This is the safeguard against the hospital scenario: being unreachable is not being dead.
5. Settle. Window passes with no veto → the transfer finalizes. It cannot be blocked, reversed, or intercepted by anyone at that point — including the people who built the contract.

What it protects against — and what it can't

Honest implementations are explicit about both columns:

The questions to ask any dead man's switch

• "Can the operator touch my funds?" The only acceptable answer is a provable no — in Will & Key's contract, vault balances are arithmetically outside the admin's reach, and that's verifiable in the source, not a policy promise.
• "What happens if the company disappears?" The contract must keep working with the website gone. Claims must be finalizable by anyone, not by the operator's server.
• "Can the fee change under me?" Look for a hard cap in the bytecode and a locked rate per vault. Ours: 0.5% on settlement only, capped at 1% forever, locked at vault creation.
• "Is it upgradeable?" An upgradeable inheritance contract means someone can change the rules after you're gone. Non-upgradeable is the right answer even though it makes the developer's life harder.
• "Has it been audited?" If the answer is no — as it currently is for our own testnet deployment — the product should say so on every page and refuse your real funds. Check that it does.

The trade you are making

A dead man's switch converts the inheritance problem into a liveness problem. You no longer need to trust an institution, share a secret, or teach your family cryptography. In exchange, you take on one recurring obligation: check in, on a schedule you chose, for the rest of your life. Whether that trade is good depends entirely on whether checking in is easy — which is why the mechanism pairs naturally with reminders that escalate long before anything is at stake, and why the timer minimums are measured in weeks, not hours.

Further reading: what happens to your crypto when you die · a complete inheritance plan in one weekend.