Authentication to zkRollups: building a crypto app


The Numio app looks simple because it is, on the outside at least. On the inside is a huge amount of innovation designed to address some of the major problems stifling widespread cryptocurrency adoption.

Hello Numio

It’s taken a while to get there, but the Numio app is now on the verge of public release, complete with zkRollups. We have designed and built it from the ground up with a fantastic group of developers. We have had multiple audits. We have tested internally, we have tested with a small group of community testers, and we have load tested with a third-party to ensure we will be able to meet demand, and allow our product to scale.

The app we have now is nothing like its original form. Almost everything has been built from scratch or is a custom implementation of the integrated tech. The scale of innovation in this app is huge.

The A-Z of Numio tech


Two-factor authentication (2FA) was a must for all our products. Current third-party authentication systems are too clunky and not particularly user friendly so we designed and built a better version.

The following example shows how it works on a cryptocurrency exchange;

  1. Authentication starts as soon as you request access to an exchange. The website requests an access code from Numio and then displays it as a QR code.
  2. You open up the Numio app and scan the QR code.
  3. Then you are shown the relevant information on the app and are asked “do you want to share your information with ‘ExchangeName’ so that you can login? — confirm this with fingerprint/face-id or PIN”.
  4. If you give permission to share your data with the exchange, then this information is encrypted, in-app, with public/private key cryptography into a neat little package.
  5. Your app sends the package to the exchange, who then forwards it to the account holders registered Numio ID.
  6. At this point your app will process the encrypted return message and verify that it is an authentic login attempt.
  7. If the request is authentic, the app sends a success response to the exchange and you are granted access. If it’s not, then the response of a failed attempt is communicated and you are denied access.


Our app uses biometric login and authentication so you can interact with logins and confirm payments at the touch of a finger.

Crypto Purchasing

You can add debit cards and use them to make in-app crypto purchases (US only at first), and load up your wallets in just a couple taps.


The app has been designed with simplicity in mind. We have removed unnecessary buttons, text and input fields.


When it comes to identity management, private data is constantly getting stolen from online databases to be sold by criminals. It’s a constant game of cat and mouse between the database holder and hackers. Just one breach can be devastating. Of course, companies can make databases and firewalls more secure but the weak point, a single point of entry for the entire database, remains.

This is why our newly designed cloud software utilises zero-knowledge proofs (zkProofs) to secure and protect virtually any type of data. NumioCloud can store all kinds of information, from backups of private-keys and credit/debit card data, to personal identity documents for KYC/AML. Locked up and secured with on-device biometrics (and no backdoors), you have full control over what happens to your data and who you share it with

What about KYC at exchanges and other third parties? Well, with Numio the documents themselves never leave your device, so you can be safe in the knowledge that no nefarious party has a copy of your passport.

Names not account numbers

Instead of long complicated account numbers, we have made it so you can choose your own username and use that for sending payments.

Numio API

The Numio API has been opened up to not only allow the Numio app and Vault to communicate seamlessly, but 3rd parties as well. We have plans in place to add more endpoints as well.


It is confirmed that the app is being launched with ETH, USDC and PHNX.

Watch our social media channels to find out what other tokens will get the power of Layer 2 mobile payments.



You will have two wallet options when using Numio.

  1. Our Standard Wallet 🐢, Layer 1 (Ethereum).

    Top-up and withdraw to external addresses and make transactions in the traditional manner (Ethereum Layer 1).

  2. Our Numio Wallet ⚡️, Layer 2 (zkRollups).
    This wallet allows you to make extremely cheap, instant transfers, and you can choose to withdraw to any Standard Ethereum address.


Fees are a deal-breaker in crypto transactions. Who would want to pay a $3 fee on a $5 transaction as was the case with our smart wallets app build?

The fees on our Smart Wallet app were a problem

After much research and testing of the different scaling solutions, the team at Numio decided to go with zkRollups.

It’s a scaling solution that helps the Ethereum Network process transactions and compute data more effectively. It is able to bundle hundreds of transfers into one single transaction, and shares the fees across them all, so each user pays a fraction for their transaction.

The big question… when can you get your hands on it?

The app will hit the Google Play Store on the 14th December 2020 (iOS to follow soon after).


Want to learn more?

If you are interested in integrating Numio tech into your platform, having a demo, or simply want a chat with our devs, then please contact us at or via one of our social channels.

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