Harry Tang

Send BTC from offline wallet

Send BTC Offline
Send BTC Offline

Introduction

On 19 February 2026, I published a tutorial on creating a secure offline BTC wallet. Today, I'll show you how to send BTC from that wallet securely - without ever bringing your offline environment online.

Prerequisites

  1. An offline VM or PC with coinb.in's source code.
  2. Your BTC private key.

Step-by-step

  1. On an ONLINE PC, open Coinb.in’s New Transaction page.

  2. Paste the BTC address(es) that hold the funds you want to spend, then click Load.

  3. Open the Inputs tab to review the unspent outputs (UTXOs) available to spend.

  4. Enter the recipient BTC address(es) in the Outputs tab.

  5. Set the amount(s) and the transaction fee (you can estimate fees with the Bitcoin Fee Calculator).

  6. Click Submit to generate the unsigned transaction.

    BTC Transaction

  7. Copy the unsigned transaction to your offline machine (e.g., via USB).

  8. On the OFFLINE machine, open your local index.html (Coinb.in source) and go to the Sign transaction page.

  9. Paste the unsigned transaction and your BTC private key, then click Submit to sign it.

    Sign Transaction

  10. Go to the Verify page to verify the signed transaction.

    Verify Transaction

  11. Copy the signed transaction back to the online PC.

  12. On the ONLINE PC, go to Coinb.in's Broadcast page and submit the signed transaction to the Bitcoin network.

    Broadcast Transaction

  13. A miner will include your transaction in a block once it’s accepted (timing depends on the fee).

  14. Done! Your BTC should be sent shortly.

Conclusion

You've now sent BTC securely from a fully offline cold/paper wallet. Your private key never leaves the offline machine, so it remains completely offline during the signing process - eliminating the risk of it being exposed or stolen online.

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