Sign a spend with Sparrow

Sparrow is a mature, open-source Bitcoin wallet for desktop. If you are not using Fountain, this is the usual way to sign a SignBit transaction with your own key.

1. Install and verify Sparrow

Download Sparrow from its official site and verify the signature it publishes before running it. You are about to hand this program your key, so it is worth the extra minute.

2. Build the spend in SignBit

On your vault, choose Send, enter the recipient and amount, and pick a fee. SignBit builds an unsigned transaction and offers it to you as a file, as text, or as a QR code.

3. Open it in Sparrow

In Sparrow, load the transaction. Sparrow reads it independently and shows you what it actually does.

4. Check the recipient and amount in Sparrow

This is the step that matters. Read the recipient address and the amount in the Sparrow window, not in ours. If they do not match what you intended, stop there. Do not sign it, and contact support. Signing off-platform is only worth anything if you use it to check our work.

5. Sign

Sign with your key. Sparrow adds your signature and leaves every other slot untouched. Your private key never leaves your machine.

6. Send it back to SignBit

Export the signed transaction and paste, upload, or scan it back into SignBit. We add our co-signature and broadcast it to the Bitcoin network.