Sign with Fountain

Fountain is the free SignBit signing app for Windows, macOS, Linux, and Android. It holds your keys and signs completely offline; it never makes a network call.

1. Install Fountain

Download it from the SignBit download page and check the SHA-256 checksum shown there against the file you got. From version 0.6.4 the Windows build is signed by SignBit Ltd, and Windows shows that name as the publisher when it runs. On Android you can also install Fountain from Google Play, which keeps it up to date.

2. Create or import a key

Set a passphrase, then create a new key or import an existing 24-word phrase. Fountain generates keys to the exact specification SignBit vaults use.

3. Back up Fountain

Open Settings, choose Export backup and save the file somewhere you trust, away from this device. It holds your keys and vaults, encrypted with your passphrase, and restores on any device. Write your passphrase down or keep it in a password manager, never in the same place as the file, because nobody, SignBit included, can open the backup without it. You can also note the 24 words if you want a second way back to the key, but you do not have to.

4. Export the public key and enroll it

Fountain exports the account public key and fingerprint. That is all SignBit needs and all it ever receives. Enroll it in your vault.

5. Sign a transaction

Move the transaction into Fountain by copy and paste, by file, or by QR code. Fountain shows you the outputs, the amounts, and the fee, worked out from the transaction itself, not from anything we told it. Sign, then carry the result back the same way.