CoolWallet S Review – All you need to know about the Hardware Wallet in Credit Card Format


In our CoolWallet Review the wallet stands out mainly because of its good reputation and its somewhat unusual size.

This hardware wallet weighs just 5 grams and is very small with 86 x 54 x 0.8mm. Is the purchase worthwhile according to our CoolWallet Review? For which user behaviour does the hardware wallet make the most sense?

At the beginning of January the hardware wallet manufacturer Ledger announced an upgrade of its well-known Nano S. From March 2019 it will be possible to manage your Bitcoin and other crypto currencies with the successor Nano X via Bluetooth and the mobile app.

The company CoolBitX has been offering the possibility to connect a hardware wallet with the smartphone via Bluetooth with its CoolWallet S since the beginning of 2018. The wallet in credit card format is set up and used exclusively with the smartphone.

How well the CoolWallet S perform in my test and whether I give it a clear purchase recommendation, you can find out in this article.

Who built the CoolWallet S ?

Behind the CoolWallet S is the Taiwanese manufacturer CoolBitX. It was founded in 2014 by Fintech entrepreneur Michael Ou and reinvented the future of cold storage in 2016 with the release of its first-generation CoolWallet, the world’s first-ever mobile hardware wallet for Bitcoin owners.

Driven by this success, several investors joined the company in 2017, which made enough capital available to develop a successor to the first CoolWallet.

With feedback from the First Wallet Generation, an improved version, the CoolWallet S, was released in early 2018. According to the manufacturer, more than 150,000 units have been sold so far.

CoolBitX’s mission is to leverage the best of blockchain technology in order to foster a more secure and empowered future for cryptocurrency investors.

Is the CoolWallet S safe ?

The CoolBitX company has installed a CC EAL5+ certified security chip in its hardware wallet, which is also used for military purposes.

The complete processing of a transaction takes place within this microchip. Therefore, only non-critical data is transmitted via the Bluetooth connection.

Your private key never leaves this chip if used properly!

A Bluetooth connection of the CoolWallet S can only be established when the wallet is switched on and is secured with the AES 256 encryption method.

As an additional security function, the microchip is sealed so that physical access to it is almost impossible. This means that the hardware is irreversibly destroyed during the disassembly attempt.

Secure transactions

To execute a transaction requested by the app, press the button on the hardware wallet. In addition, all necessary information will be shown again on the E-Ink display.

Overall, the CoolWallet S thus offers a very high level of security.

CoolWallet S – What’s in the Box

The CoolWallet S is delivered in a stylish black cardboard box which can be opened upwards. Immediately after opening, the hardware wallet shines at you in the form of a bank or credit card.

Included in delivery:

  • CoolWallet S with E-Ink display
  • Charger with USB cable
  • Recovery Seed Card
  • Stickers

How can I find out if I have an original CoolWallet S ?

The packaging of the CoolWallet S is closed with a seal. However, this type of protection is not the most effective. It is easy to reproduce the adhesive labels.

Unfortunately there is no other way to verify the authenticity of your CoolWallet S. Here the Genuine-function, as with the Ledger Nano S, would be desirable.

If you want to be on the safe side, we would recommend to only order the CoolWallet S directly from the manufacturer. In our case, the delivery was fast and problem-free.

The CoolWallet S set up in 4 easy steps

The hardware wallet can be set up quickly and easily. All you need is a mobile phone with the latest Android or iOS version. During the entire setup procedure, the CoolWallet S should be charged with the supplied charger.

Be sure to insert the card the right way round. The arrow of the charger must be on the front of the card. A red LED next to the display indicates the charging process.

1. Pair the CoolWallet S with your mobile phone via Bluetooth

  • To pair the CoolWallet S, first install the CoolBitX App from the Apple or Google Play Store. Simply scan the QR code on the Recovery-Seed card.
  • Press the button of the CoolWallet S once and turn it on. It will show “Please pair” in the display.
  • Now open the CoolBitX App and press the “Connect” button.
  • A message appears to confirm the connection by entering the Bluetooth password. The required password is shown on the CoolWallet S display.

2. Update the CoolWallet S firmware

Immediately after pairing, the app checks whether there is a firmware update for the CoolWallet S and installs it if necessary. For security reasons, I recommend that you always use the latest firmware.

If you have already set up your CoolWallet S, you will need your recovery seed for recovery. The wallet will be completely deleted during the firmware update!

3. Create a new wallet

After you have confirmed the successful firmware update, the CoolWallet S restarts. To reconnect, press the “Connect” button in the app and the button on the hardware wallet.
Now it is time to create a new wallet account. Press the “Create” button to continue.

4. Create CoolWallet S recovery seed

The CoolWallet S gives you several ways to choose the length and location of your recovery seed. I recommend that you select 24 words, or more precisely, sequences of numbers, to be displayed on the wallet’s E-Ink display.

Once you have made your selection, you can press the button on the CoolWallet S to display the next combination of numbers in the row.

Write all 24 rows of numbers on a piece of paper, or better yet, on a non-destructible stainless steel note, such as a Cryptosteel.

After you have noted down all the sequences of numbers, you must verify your wallet backup to complete the setup.

To verify the recovery seed, you must sum up all the numbers one by one. Then enter the result into the input mask of the app.


Recovery phrase:   11111; 22222; …    
Total numbers:  = 11111+22222    
Result of the verification = 33333

Personally, I had my problems with this verification method and had to add all the numbers several times to get the correct result. After all, it takes 120 characters at a time to enter correctly into the calculator!

I would definitely prefer a query of individual phrases with direct confirmation, which is available with the app set up, but they don’t recommend it for security reasons.

Recovery seed with numbers?

CoolBitX has decided to use a sequence of numbers instead of words in its wallet to make it easier for non-English speaking users.

The technique behind it is the same. If you prefer to work with the known words, you can use a table to convert back the sequence of numbers.

CoolWallet S Review – The Conclusion

The CoolWallet S with its credit card format and mobile operating concept can be described as a revolution in the hardware wallet market. The built-in battery is large enough to use the CoolWallet S for several weeks without having to recharge it.

The app UX is tidy and while it could be enhanced, it comes with all the features you need. The integration of Changelly makes it possible to switch between individual assets quickly and easily, anywhere in the world – provided there is an Internet connection.

Setup is largely trouble-free. What I personally didn’t like is the verification of the recovery seed, but you go through this process only once every while. The wallet offers the possibility to work with fewer sequences of numbers or to use the app for creation, but this is at the expense of security.

Unfortunately, CoolBitX comes without an operating system, so that new features can only be imported by a firmware update. There is always the danger that you have to restore your wallet with the Recovery-Seed.

In daily life

The CoolWallet S combines the advantages of a hardware wallet with the advantages of a mobile wallet while eliminating the weaknesses of both.

All in all it is a very cool feeling to have your Bitcoins available at all times and to have them really safely stored.

With its CoolWallet S, the manufacturer CoolBitX certainly makes a contribution to the mass adaptation of crypto currencies. The beginning is made, with a simplified backup of the wallet and more acceptance points I see a lot of potential for the future.

More hardware wallet tests can be found in our big upcoming hardware wallet comparison article.