Canary

Canary is an early warning system for bitcoin you are not actively spending. Cold storage is by design something you rarely check, which means an unauthorized spend could sit unnoticed for months. Canary watches those wallets continuously and tells you the moment anything moves.

It is watch-only and never asks for a private key. You add an output descriptor or extended public key exported from the wallet you already use — Sparrow, Electrum, BlueWallet, or a hardware device such as a Coldcard, Ledger, or Trezor — and Canary tracks the addresses derived from it. Step-by-step export guidance is included for each supported wallet.

Beyond plain send and receive alerts it recognizes patterns worth knowing about: replace-by-fee bumps, child-pays-for-parent acceleration, and consolidations. Balance alerts fire when a wallet crosses a threshold you set, in bitcoin or in fiat, with crossing detection so a balance hovering at the line does not flood you with messages.

Notifications are delivered through ntfy.sh, which can itself be self-hosted, in any of nine languages. A dashboard on your MyNode shows balances, transaction history, and pending activity, with fiat conversion alongside. Because it runs locally using the Bitcoin Development Kit, the addresses you monitor are never handed to an outside service to watch on your behalf.