Fortress-grade self-custody

Secure your Bitcoin for generations.

COINCUBE is open-source Bitcoin self-custody with built-in inheritance and time-locked recovery.

Your savings, your spending, your legacy.

Keep your Bitcoin safe for the long haul, spend it from anywhere, and leave it to the people who come after you, always in your control.

Your savings and your spending in one app: Vault holds your savings with inheritance built in, and Spark is what you spend day to day.

Turn a phone into a signing device for your Vault. Your keyholders (a partner, an heir, a friend in another city) carry it in their pocket.

The optional backend that glues Tenshu and Keychain together. It sees xpubs and PSBTs, never your keys, and the apps work without it.

Your keys never leave your devices. Hardware wallets keep them offline. Math enforces the rules.

Multiple keys spread across devices and locations. Losing one key doesn't mean losing your Bitcoin.

If a key is lost, a secure backup path activates after a set time. No custodians, no third parties.

Your Bitcoin passes on to the right people, at the right time, without lawyers or intermediaries.

Inspect Tenshu’s public source and review the evidence for each release.

For those who want to see under the hood.

Technical specifications

Network Bitcoin + Spark

Smart Contracts Miniscript (Bitcoin Script)

Transaction Format PSBT (Partially Signed Bitcoin Transactions)

Key Management Multi-signature with configurable quorums

Hardware Support Ledger, Coldcard, Blockstream Jade, BitBox

Platforms macOS, Windows, Linux (desktop-first)

Companion App Keychain (iOS, Android) for mobile signing

Source Open source, auditable on GitHub

Self-sovereign Bitcoin. Be first in line.