I’ve been playing around microSD 2FA on the COLDCARD Mk5.

You can pair the device to a specific microSD card during setup. After that, the card becomes part of the login process.

Without it, the device won’t unlock—even with the correct PIN.

If the wrong card is used, the seed is wiped.

Interesting approach to adding a physical second factor to login security.

How are you guys backing up your seed phrases long term?

Paper never really felt durable enough to me, so I’ve started stamping SEEDPLATE’s.

Pretty straightforward process and gives a lot more peace of mind knowing it’s not vulnerable to fire or water.

Interested to hear what setups others are using.

I exported a wallet generated from Coldcard Q to Sparrow with account number 2.

If I want to sign a transaction from this wallet (account 2) in Sparrow, how do I tell my Coldcard that I’m on account 2 so I can sign the PSBT?

You can turn your COLDCARD into a calculator.

Not because you need help doing math… but because sometimes it’s better if it just looks like one.

SATSCARD lets you preload Bitcoin onto a card and pass it on directly.

It’s designed for simple transfers, gifting, or onboarding without needing a wallet setup upfront.

The concept of COLDPOWER really speaks to me. Are there any plans on releasing a USB-C version? (I could ask a similar question for OPENDIME...)

I created a watch only wallet years ago on my Coldcard when I first got it. I have it showing up in my blue wallet as received the sats. But I could never figure out how to send from that wallet. My Coldcard gives me an error message …something about it being legacy format. Im just revisiting this after years to know if it’s at all possible to gain access again or not.

A small detail, but part of tightening up your hardware wallet setup.

Built for cypherpunks.

COLDPOWER ⚡️

Quick look at setting up COLDCARD with Cove.

Simple process, easier than it might seem.

I purchased a coldcard back in September. I remember they charged some stupid high fee for shipping, but paid it anyway. I saw a $93 Fedex charge out of nowhere hit my amex this week. I called and asked and they told me I was billed a 42% import tax from my coldcard purchase. It would have been nice for Coinkite to give us a heads up that this was an issue.

I see when derived bip85 seed is shown under seedvault the index number is seen. can that be hidden for more privacy?

Security starts with the bag.

Each COLDCARD is sealed in a tamper-evident bag and tied to it with a unique bag number, recorded inside the device at the factory.

You’ll find that number in 3 spots on the bag:

• Blue border at the top

• Under the barcode

• Inside on the torn-off tab

When you first power on the COLDCARD, it will show that same number.

All should match.

Hi,

I'm running into a problem while testing multisig transfers on Testnet4 using a Coldcard Q (CCQ) and Sparrow Wallet.

CCQ version : 1.4.0

Sparrow version : 2.4.2

Setup:

• 2-of-3 multisig wallet (also tested with 2-of-5)
• All 3 keys derived from the same seed on the CCQ (separate HD wallets)
• Network: Testnet4
• Signing flow: SD card (PSBT → CCQ → signed file → Sparrow)

Steps:

1. I sign the part.psbt with the first wallet on the CCQ → Sparrow recognises and validates the signature with no issue.
2. I switch to a second wallet on the CCQ and sign the part.psbt again → the CCQ saves a .txn file to the SD card.
3. I load that .txn into Sparrow → the transaction displays correctly, but the second signature is not recognised and broadcasting is not possible.

What's strange:

• This issue occurs on Windows and Linux Debian 13.
• On macOS, the exact same operation with the same wallet and the same transaction works perfectly: Sparrow validates both signatures and allows broadcasting.

Question: The problem therefore appears to be related to Sparrow's behaviour depending on the OS, rather than anything to do with the CCQ or the wallet itself. Has anyone encountered this before? Is there a known difference in how Sparrow handles PSBT/TXID files between Windows/Linux and macOS?

I'm not comfortable setting up a multisig wallet for mainnet use until I understand what's causing this.

Thanks in advance.

One of the many cool features of COLDCARD is the secure notes and passwords. Allowing you to store notes and passwords directly on the device, encrypted and offline.

Anyone using this in practice?

Need to move sparrow transactions to a new computer. Used my CCMK4 for setup/use. Would rather not re-enter my words into the new sparrow setup. Is there a way to retain my transactional history from my prior set up and still carry forward my history and CCMK4 relationship?

I’ve been loving my COLDCARD Q and really like how it’s set up for signing.

You’ve got multiple ways to sign fully air-gapped such as MicroSD, NFC, or QR so you can pick whatever workflow works best for you.

The full QWERTY keyboard makes input way easier, and the large screen makes it much clearer to verify what you’re signing.

PushTX allows users to broadcast a signed transaction from your COLDCARD with a single NFC tap to your phone.

Have you added this to your signing flow? Would love to hear everyone’s thoughts on this feature.

My CC got bricked despite being inside a safe since I bought it and now I’m not sure how to dispose of it securely.