COLDCARD Mk4 v5.3.2 and Q Firmware v1.2.2: NFC Push Tx & More

COLDCARD Mk4 firmware v5.3.2 and Q firmware v1.2.2 have been released. It introduces several new features, along with various enhancements and bug fixes. Notably, the update includes NFC Push Tx, which enables the transmission of signed transactions to the blockchain via NFC and a web service.

COLDCARD Mk4 v5.3.2 and Q Firmware v1.2.2: NFC Push Tx & More
  • "This is a release with a many small bugfixes and little enhancements… plus one major new feature: NFC Push Tx. You can now simply tap your COLDCARD to your phone to broadcast the transaction without a computer or any new apps," announced Coinkite.
  • See NFC Push Tx under Settings to enable and select a service provider, or your own webpage. You can provide your own backend for complete transaction privacy.
    • As of today, there are two public services supporting this feature: and Both of these options are shown in the settings menu in the COLDCARD firmware.
    • Learn more at

What's new

  • PushTX: once enabled with a service provider's URL, you can tap the COLDCARD and your phone will open a webpage that transmits your freshly-signed transaction onto the blockchain. See Settings > NFC Push Tx to enable and select service provider, or your own webpage. More at pushtx org. You can also use this to broadcast any transaction found on the MicroSD card (See Tools > NFC Tools > Push Transaction).
  • Transaction Output Explorer: allows viewing all output details for larger txn (10+ output, 20+ change) before signing. Offered for large transactions only because we are already showing all the details for typical transactions.
  • Setting to enable always showing XFP as first item in home menu.


  • When signing, show sum of outgoing value at top. Always show number of inputs/outputs and total change value.
  • Add Sign PSBT shortcut to NFC Tools menu
  • Stricter p2sh-p2wpkh validation checks.
  • Show master XFP of BIP-85 derived wallet in story before activation. Only words and extended private key cases.
  • Add Theya option to Export Wallet
  • Mention the need to remove old duress wallets before locking down temporary seed.

Bug fixes

  • Decrypting TAPSIGNER backup failed even for correct key.
  • Clear any pending keystrokes before PSBT approval screen.
  • Display max 20 change outputs in when signing, and max 10 of largest outputs, and offer the Transaction Output Explorer if more to be seen.
  • Calculate progress bar correctly in Address Explorer after first page.
  • Search also Wrapped Segwit single sig addresses if P2SH address provided, not just multisig (multisig has precedence for P2SH addresses)
  • Address search would not find addresses for non-zero account numbers that had been exported but not yet seen in a PSBT.

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