CobaultOwned together. Signed together.
Group-owned bitcoin often starts in one person's wallet because that is the easiest way to begin. A shared vault keeps the convenience of one place to hold it, but gives the group an actual signing rule.
The compromise groups often start with
Two co-founders bought bitcoin before the business had proper controls. A family put money in together. A club or syndicate holds bitcoin for the group.
In each case, one person usually set up the wallet. One person has the seed phrase. Everyone else has trust, messages, or a spreadsheet.
That is a normal starting point. The weakness shows up later: a dispute, a mistake, a missed message, or a basic question about who can move the bitcoin.
The group usually wants three things: nobody moves it alone, everyone can see what is proposed, and the signing rule matches the ownership.
Why copied seeds do not solve it
The usual answer is one person's wallet plus trust. Sometimes a second person holds a copy of the seed.
A copied seed does not create shared control. It gives another person full access. That is the familiar compromise: another person can now move the bitcoin, but the group still has not agreed a signing rule.
For a group that mostly wants to hold bitcoin, heavier arrangements can also feel like too much: expensive custody on one side, or a self-managed multisig setup that someone in the group has to operate correctly.
How a shared ownership vault helps
A shared vault is a standard bitcoin multisignature address. Each owner can hold a key, and the group chooses how many signatures are required before bitcoin moves.
For two partners, a 2-of-2 vault is easy to understand: both must sign, so neither can spend alone. It also has no lost-key tolerance. If either key is lost, the vault is frozen.
A 2-of-3 vault keeps the "neither alone" rule and adds tolerance for one lost key. The third key can be held by one of you on another device, or by someone both of you choose. For a larger group, a 3-of-5 vault can do the same job.
In a 2-of-3 vault, one owner cannot move the bitcoin alone. If one key is lost, the other two keys can move the bitcoin to a new vault. Every spend starts as a proposal that keyholders can see: destination, amount, proposer, and signatures so far. Nothing moves until the quorum signs.
One owner cannot move it alone.
Two keys, both required, have no lost-key tolerance.
For a larger group, the same idea can be a 3-of-5.
Cobault tells you when you choose a quorum with no lost-key tolerance. The group still makes the choice, but it chooses the signing rule up front instead of inheriting it from the person who first set up the wallet.
During launch, shared vaults are free to set up. Vaults created during the launch window stay free.
A common partner setup
For two owners, a practical 2-of-3 setup is:
- One key held by the first owner.
- One key held by the second owner.
- A third key held offline, on another device, or by someone both owners choose.
Any two can sign. One owner cannot move the bitcoin alone. If one key is lost, the other two can move the bitcoin to a new vault.
For a larger group, the same idea can be a 3-of-5: enough people to avoid one-person control, with tolerance for one lost key.
How it works
- Agree how many keys there will be and how many must sign.
- Create the shared vault and add the keyholders.
- Send each claim link privately to the right person.
Each keyholder accepts, creates or connects their own key, and keeps their own backup. When all keyholders have accepted, each participant checks the final roster, quorum, and address. Once everyone acknowledges the same vault, it becomes active and its address is fixed. Then move the bitcoin into it.
Verify it yourself
In a standard shared vault, Cobault holds no key. A single owner cannot spend if the vault requires more than one signature. Cobault cannot spend because it is not a keyholder. We coordinate proposals and signatures, but we cannot sign or move your bitcoin.
How keys are generatedThe vault is a bitcoin address. Any keyholder can check its balance and transactions in a block explorer. The explorer-verification guide should show how to match that address to the vault details and how to read the transaction record.
Explorer-verification guide — publishing soonYour vault is recoverable without Cobault if enough keyholders have their seed phrases and recovery kits. Each keyholder should download their own recovery kit at activation. The kit contains the vault details needed to reconstruct the vault address and signing path, including the quorum, participant roster, network, and derivation information. It does not contain anyone's seed phrase and cannot sign by itself.
The shared-vault recovery guideCobault implements Craton.
Limits to understand
- It does not stop a quorum acting together. In a 2-of-3 vault, any two keyholders can spend without the third. That is the arrangement working as designed.
- It does not protect a 2-of-2 vault from a lost key. If either key is lost, the vault is frozen. The lost-key tolerance described above belongs to the 2-of-3 configuration.
- It does not wait for conditions. A standard shared vault moves bitcoin when enough keys sign. If you need movement only after an agreed event, that is not Tier 1. Policy vaults are provided for by the standard Cobault implements but are not yet available.
- It does not recover a lost seed. Each keyholder must back up their own seed phrase and recovery kit. Cobault and the other owners cannot recreate a lost key.
- It does not keep the arrangement private. The address, balance, deposits, and spends are visible on the public bitcoin network. Keyholders also see each other's display names, account email addresses, and public keys inside Cobault.
- It is not custody. Cobault is coordination software, not a custodian, bank, or deposit-taker. Bitcoin in a vault is not covered by a government guarantee or compensation scheme. It is not a partnership agreement or a substitute for one.
Next step
Or read the walkthrough first: a 2-of-3 vault for partners. Publishing soon.