Learn how to use ColdCard MK4

Master one of the most secure hardware wallets in Bitcoin with The Mastering Bitcoin Self Custody and Security Course. In this section, we take a deep dive into the ColdCard MK4 and show you how to use it in a fully air-gapped setup for maximum security. From hardware setup and firmware verification to advanced passphrase and multi-account configurations, this section gives you everything you need to confidently secure your Bitcoin using ColdCard.

Why Learn ColdCard MK4?

The ColdCard MK4 is considered one of the most secure Bitcoin wallets available. It’s built by Bitcoiners, for Bitcoiners—with a focus on advanced features and uncompromising security. ColdCard is a Bitcoin-only device, meaning it has a smaller attack surface and its developers can focus entirely on improving Bitcoin security. Its fully air-gapped design ensures your private keys never touch an internet-connected device, and it offers advanced options like passphrases, dice-roll entropy, multisig support, and account management.

If you're serious about long-term Bitcoin custody and privacy, ColdCard is the gold standard.

By learning to use ColdCard, you’ll be able to:

  • Use a fully air-gapped setup for maximum security

  • Verify and update your device’s firmware securely

  • Use Sparrow Wallet as your wallet coordinator

  • Apply passphrases for enhanced protection and plausible deniability

  • Create and manage multiple accounts under one seed phrase

Master ColdCard in The Bitcoin Course:

Why ColdCard MK4?

This video introduces the ColdCard MK4 and explains why it’s considered one of the most secure wallets available. You’ll learn what makes ColdCard different: Bitcoin-only firmware, fully air-gapped operation, open-source code, and advanced features for experienced users.

Shopping list: what you need to secure ColdCard

Before setting up your ColdCard, you'll want to gather a few key items to enable a fully air-gapped setup: the most secure way to hold bitcoin. This video outlines the essential gear and explains why each piece is important for using ColdCard securely and effectively.

How to Verify and Update ColdCard Firmware

Learn how to verify and update your ColdCard firmware—a critical part of device security. You’ll learn how to check the current firmware version, download the latest version, and verify it before loading it onto the device.

How to Use ColdCard with Sparrow Wallet (Air-Gapped)

Learn how to use ColdCard with Sparrow Wallet in a fully air-gapped setup. We cover seed generation, exporting your wallet to Sparrow via SD card, receiving funds, and building transactions in Sparrow. You'll then sign those transactions on ColdCard and broadcast in Sparrow. Your private keys never touch the internet.

How to Apply and Use a Passphrase on ColdCard

Learn how to apply a passphrase to your ColdCard to create a hidden wallet. You’ll learn how passphrases work, why they’re powerful, and the critical importance of backing them up correctly. We walk through sending and receiving funds using the passphrased wallet, verifying access, and testing functionality—all while maintaining maximum security.

How to Create Different Accounts in ColdCard

A single ColdCard seed can manage multiple accounts, making it easy to separate personal, business, or no-KYC funds. In this lesson, we show you how to assign different account numbers during wallet export and how to manage those accounts using Sparrow Wallet. Each account has its own addresses and transaction history, allowing for clean separation and easy organization.