Coldcard Review

Updated May 31, 2024

Our Verdict

If you only plan on holding Bitcoin, the ColdCard might be a good option for more technically advanced users.

Buy ColdCard

What is ColdCard?

ColdCard is a Bitcoin-only hardware wallets.

It allows you to send, receive, and store Bitcoin.

It is one of the few hardware wallets that only supports Bitcoin.

Because of this, ColdCard comes with a very unique set of features.

And ColdCard’s latest version - the Mk 4 - offers even more, which we will cover in detail below!

CardCard Mk 4 features

Before we cover those features in more detail, let’s briefly discuss all of the benefits that cold storage wallets offer.

Benefits of a Cold Storage Wallet

Hardware wallets are designed to be unhackable. They keep your cryptocurrency safe because every transaction must be approved by physically pushing a button on the device. You should be able to plug your hardware wallet into a virus-infested computer without much risk to your funds.

Hardware wallets are also convenient in that they make it much simpler to back up your crypto holdings. Instead of having to write down and copy seed phrases for a bunch of different crypto wallets, it’s possible to write down the seed phrase for just the hardware wallet and then restore all of the other crypto wallets loaded on that device.

As a rule of thumb, if you have crypto that’s worth more than the cost of a hardware wallet you should probably invest in a hardware wallet.

With that in mind, let’s look at the Coldcard and what makes it different from other crypto wallets.

➤ MORE: Bitcoin Cold Wallets Guide

Advantages of the Coldcard Mk 4

Key Takeaways

  • ColdCard is Open Source: anyone can look at the code running on ColdCard and make sure it is safe.
  • ColdCard has an NFC chip: you can simply tap the Coldcard against your phone to complete PSBTs (partially signed Bitcoin transactions).
  • ColdCard comes with a protective plastic case to protect your hardware and coins.

Here are some of the main advantages of using a Coldcard.

Secure Supply Chain

One feature of the ColdCard that makes it stand out from the competition has nothing to do with the actual hardware at all.

The supply chain!

Coinkite, the creator of the ColdCard, really went out of its way to make sure you feel confident the hardware has not been tampered with before you receive it.

To do this, they layer epoxy resin over all the internal components and soldering so it would be obvious if they were changed.

The Mk 4 also comes in a sealed plastic bag that is numbered. This number can also be seen labeled permanently on the actual board of the ColdCard, which you can easily see since the case is transparent. If the numbers on the ColdCard and the bag don’t match, it probably means the bag was opened, tampered with, and replaced. It’s certainly not full-proof, but this attention to detail is appreciated and unique. And measures like these do make it more difficult to tamper with the product.

CardCard Mk 4 supply chain

Easy to Hide

The ColdCard essentially looks like a basic calculator. This means it is easy to carry with you without drawing the attention of the people around you.

Support for Other Wallets

Several Bitcoin wallets have built-in Coldcard support.

CardCard Mk 4 supported wallets

For example, Electrum supports the Coldcard and even allows users to create offline transactions with an air-gapped Coldcard.

Which brings us to the next feature.

Offline Transactions

The Coldcard is specifically designed to allow for transactions without connecting the hardware to any internet-connected device. While it is possible to use other hardware wallets without connecting them to the internet, the process is more difficult given that they don’t have a Micro-SD card slot or NFC chip like the Coldcard Mk 4 does.


All of Coldcard’s code is open-source, meaning that anyone can audit it if they want to make sure it is secure. More eyes on the code means bugs are also found faster and you know there are no back doors put in by the developer.

Disadvantages of the Coldcard Mk 4

The following are the drawbacks associated with using the Coldcard.

It’s Expensive

At $160 USD, The Coldcard Mk 4 costs about twice the cost of other leading hardware wallets.

Bitcoin Only

The Coldcard can only custody Bitcoin whereas most other hardware wallets can custody dozens or hundreds of cryptocurrencies.


If you only plan on holding Bitcoin, this is probably a plus for you. Since only Bitcoin is supported, the total amount of code running on the device is much less than if it supported altcoins. This reduces the amount of ways an attacker can find ways to break into the device.

Difficult to Navigate

The way the Coldcard is designed makes it harder to navigate menus than some other touchscreen hardware wallets such as the Trezor Model T. It’s not too difficult, but there are better wallets in this aspect.

Coldcard Basics

The other major feature of the Coldcard is that it only works with Bitcoin.

The Ledger and Trezor both support hundreds of cryptocurrencies (when you include ERC20 tokens). Thus the Coldcard’s functionality is severely limited as compared to other wallets. It’s designed for Bitcoin investors and Bitcoin investors only.

The Mk 4 has a bright 128x64 pixel OLED screen that can be read in the dark as well as an indicator light to prove that the device has not been tampered with. The Coldcard is made in Canada which inspires more confidence in the device than were it to be made in China.

Maximum Security

The Coldcard Mk 4’s primary selling point is security. It places heavy emphasis on being able to do everything on the device without the need for any external hardware.

It supports several features that other hardware wallet manufacturers have decided not to include with their devices. We’ll look at these Coldcard security features now…and there are a lot of them.

Air gap support

An air-gapped device is one that never touches the internet so it is fully impervious to hacking. The Coldcard Mk 4 claims to be the only hardware wallet that supports air-gapped operation without jumping through a bunch of hoops.

Set up a wallet, send funds to it, and even send outbound transactions all without ever connecting the Coldcard to an internet-connected computer at all! Using an air-gapped device is time-consuming but it does represent the ultimate in security.

It achieves this through full native support of BIP174.

bitcoin improvement proposal 174
Learn more about the Bitcoin Improvement Proposal #174 here.

Micro-SD Support

The Coldcard is the only hardware wallet that supports a Micro-SD card. That card allows an investor to easily back up the Coldcard’s seed phrase without having to write it down. Also, the Micro-SD card is what allows the Coldcard to sign Bitcoin transactions without being connected to the internet.

microsd card

The Duress Pin

The Coldcard allows a user to enter a different pin which will open up a Bitcoin wallet completely separate from the main wallet.

So for instance, if you have $10,000 worth of Bitcoin in the main wallet, you could put $200 in the duress wallet and if anyone forced you to open the Coldcard you could load the duress wallet without ever giving any indication that there are significantly more funds located in the main wallet. This is a great feature to mitigate the effects of the $5 wrench attack.

5 dollar wrench attack comic

The Brick Pin

When you set up your Coldcard, you can specify a PIN that will render the device unusable.

Why would you want to do this?

Well maybe you don’t, but some people may live in countries like Venezuela where using alternative currencies is illegal and so may need a way to destroy any proof they own them.


Unlike the duress pin, the brick pin does destroy the Coldcard so that it can never be used again. Anyone who uses the brick pin will need to buy another Coldcard if they want to keep using the hardware device.

Easy Device Destruction

Of course, if you forget your brick pin and need to destroy the device in a hurry, you can always just drill a hole right into the secure element, and ColdCard Mk 4 makes it very easy to find it. Since the case of the ColdCard is transparent, you just need to look for the words “Shoot This” and drill into it.

CardCard Mk 4 shoot these chips

Two Word Protection

Every time you open your Coldcard, it will show you two words. Each time you open the Coldcard you should check for these words as they prove that the Coldcard is yours and that it has not been tampered with.

two word coldcard phrase
This is what the two-word screen will look like.

ColdCard Mk 4 vs ColdCard Mk 3

You can see all of the improvements made over the previous version of ColdCard (the Mk 3) below:

Mk 4 Mk 3
Connection Type USB-C Micro USB
# of Secure Elements 2 1
Protective Cover Included Not included
USB-In-Use LED Yes No
Additional Secure Storage 216 bytes None
Settings Memory 512 kB 4 kB
Flash Memory (Firmware) 1.5 MB 700 kB
Memory 840 kB + 1 MB RAM 360 kB
CPU Speed 120 MHz 80 MHz
Debug Serial Port Physical Pins Virtual Pins
BTC Transaction Size Limit 2 MB 384 kB
Firmware Upgrade Time 15 sec 2 min
USB Virtual Disk Mode Yes No
Trick PINs Supported Not Supported
PSBT Location PSRAM Flash Memory
NFC-V Compatible Supported Not Supported

Coldcard Mk 4 vs Ledger Nano X

The main difference between Coldcard and Ledger is that Coldcard is Bitcoin-only.

There are two things to know about this:

  • Bitcoin-only can be better security
  • If you want to store coins besides Bitcoin, don’t get a Coldcard

The Coldcard and Ledger Nano X are both $157.

Coldcard Mk 4 vs TREZOR Model T

The main difference between Coldcard and TREZOR is that Coldcard is Bitcoin-only.

There are two things to know about this:

  • Bitcoin-only can be better security
  • If you want to store coins besides Bitcoin, don’t get a Coldcard and instead get a TREZOR

The Coldcard is $157 USD, while TREZOR is $320 USD.

Coldcard Wallet vs Other Wallets

The biggest difference between the Coldcard and other cryptocurrency hardware wallets is that most other hardware wallets can custody hundreds of coins while Coldcard is only good for Bitcoin.

There are plenty of investors who are only holding Bitcoin so this will be fine for them. However, if you’re invested in other cryptocurrencies, a different hardware wallet might be a better choice.

As far as price goes, the ColdCard sits at about the same price point as Ledger the Ledger Nano X, while the Trezor T costs $320.

So far, the Coldcard has not been shown to have any serious security vulnerabilities and based on the amount of emphasis that the Coldcard team places on security, a Coldcard may always remain one step ahead of hackers.

Where to Buy a Coldcard

If you’d like to purchase a Coldcard, the best option is to buy it directly from the Coldcard website.

CardCard Mk 4 info page

This will ensure that you receive an authentic product. Also, Coldcard ships all of their hardware wallets in tamper-proof bags to ensure that no postal carrier or other shipping agent tampers with the product.

While it may be possible to find an inexpensive Coldcard for sale on eBay or Amazon we highly recommend that you don’t purchase the wallet from one of these websites. A retailer could potentially tamper with the Coldcard so that it’s no longer secure and once you put your Bitcoin on the device they could steal it.

While the odds of this happening are probably fairly low, the risk is simply not worth saving $20 or $30. Buy the device directly from Coldcard and have the peace of mind that you’ll receive a trustworthy device.

How to Backup Coldcard

Let’s get back to the main purpose of a hardware wallet.

It stores your keys in a secure element.

Cryptocurrency stored on a computer connected to the internet is an easy target for hackers, especially for Windows users.

When you use a hardware wallet, your coins are stored offline, making it difficult for hackers to steal them.

The ColdCard uses a standard 24-word seed backup system. Using this system, the device spits out 24 words. If you ever lose your Coldcard, or it is destroyed or stolen, you use these 24 words on another wallet to get your coins back.

coldcard recovery seed
This is what the backup setup looks like on Coldcard.

While you can write these down on paper, it is not recommended. This is your backup, after all. The best way to back up your seed is using something like the Billfodl.

The PrivacyPros Billfodl is stainless steel. It allows you to recreate your seed using metal tiles, allowing your backup to be more resistant to fire, water, and other environmental dangers.


For example, one user had $1 million worth of cryptocurrency backed up on a piece of paper in a ‘fireproof’ safe. His house was flooded, and the water destroyed his paper backup seed. This would not have happened had the user been storing his backup seed on stainless steel like the Billfodl.

billfodl information

The Billfodl protects your seed from both fire and potential floods. For $80, this can be worth it depending on the amount of cryptocurrency you’re storing on your device.

Learn More About Billfodl

Is the ColdCard different than the OpenDime?

Yes. While both devices are made by CoinKite, the OpenDime is a kind of Bitcoin piggy bank where funds should only be spent from the device one time. The ColdCard is meant to be used as many times as you want. You can spend and receive forever on it.

The OpenDime is a great method of cold storage when paired with a backup.

Does Coldcard work with Unchained?

Unchained works with

  • Coldcard Mk2
  • Coldcard Mk3
  • Coldcard Mk4
  • Coldcard Q
Article Sources

BuyBitcoinWorldWide writers are subject-matter experts and base their articles on firsthand information, like interviews with experts, white papers or original studies and experience. We also use trusted research and studies from other well-known sources. You can learn more about our editorial guidelines.

  1. Arkad - How to make offline transactions,
  2. - Ledger Nano X Review,
  3. Bitcoin Github - BIP 147,
  4. - Hardware Wallets Explained,
  5. Wikipedia - Secure Elements,
  6. - Billfodl Review,

Rating: 4

About the Author

jordan tuwiner

Jordan Tuwiner is the founder of He studied computer science at Towson University and holds an online degree in trading & cryptocurrency. Jordan has been writing about Bitcoin since 2015. His work has been featured in The Guardian, International Business Times, Forbes, VentureBeat, CoinDesk and many other top Bitcoin media outlets.

: 4

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