Would you use a Bitcoin multisig vault where the company can't see your data?

I'm building a collaborative-custody 2 of 3 multisig Bitcoin vault and want to test the waters to see if anyone would be interested. Privacy is the whole point. Encryption happens on your device, the keys never leave it, and our servers only ever see ciphertext. We couldn't read your data if we wanted to.

It's a 2-of-3 multisig: you hold two hardware-wallet keys, the service holds one. So:

• We can't move your funds — our key is 1 of 3, never enough alone.
• We can't see your data — all the crypto runs in your browser; our server only stores ciphertext it can't decrypt (xpubs, descriptor, labels, even balances).
• You can always recover without us — it's a standard wsh(sortedmulti) descriptor you can sweep in Sparrow with your two keys, with or without us.
• You set the spending rules when the service key is used — address allowlists, 24h limits, and time-locks on the service key. Changing a rule needs a signature from your hardware wallet, so a stolen login can't loosen your own guardrails. The policy itself is encrypted too — we enforce it without being able to read it.

The difference from most vault/custody services: if a company can show you a total "assets under custody" number or charge you based on the amount you hold, it can read every customer's holdings. We can't produce that number from data we can't decrypt. We genuinely don't know how much you hold.

For those who are already using other multisig Bitcoin vault services would something like this be useful to you? What would it take for you to trust it?

I'm aiming to launch in the next 1-3 weeks and I'm looking for beta testers. If you want early access, let me know.