Ethereum Foundation launches Universal Ethereum Signer app on Passport Prime

Foundation, the hardware company best known for its Bitcoin wallet functions, is about to get some Ethereum company on its flagship device. CEO Zach Herbert said in an interview on Unchained Premium that the Ethereum Foundation is launching an app called the Universal Ethereum Signer on KeyOS, the operating system behind Foundation’s Passport Prime.

The app was written by Nicolas Bacca, a Ledger co-founder, and the Ethereum Foundation is working with him on the launch, according to Herbert. For Passport Prime owners, it marks the first time the device can act as a dedicated signer for Ethereum transactions through a third-party app.

What the Universal Ethereum Signer actually does

The idea is simple. Users review and sign Ethereum transactions on separate, air-gapped hardware instead of trusting a phone or laptop with their keys.

Bacca, now CEO of ZKnox, built the app with funding from an Ethereum Foundation grant to ZKnox. The app is currently in beta.

There is a catch, and it is a practical one. Right now, users have to sideload the signer manually onto Passport Prime. Sideloading means installing software directly rather than downloading it from an official store.

Herbert said a future app catalog will let trusted groups push updates directly to users. That catalog is expected to launch in winter 2026.

The model resembles F-Droid on GrapheneOS, where independent developers can ship software without waiting on a central gatekeeper.

Passport Prime and the KeyOS bet

Passport Prime retails for $349 and reached general availability in May 2026. The launch followed a $6.4 million funding round for Foundation.

The device packs a 3.5-inch touchscreen and 50 GB of encrypted storage. It combines a Bitcoin hardware wallet with FIDO security keys, two-factor authentication and encrypted file storage.

The engine underneath is KeyOS, an open-source microkernel written in Rust. It runs to roughly 9,000 lines and is designed to isolate apps from one another.

Security is the product, and the stakes just went up

In October 2026, Foundation dealt with a phishing campaign that targeted more than 23,000 customer emails. The company confirmed that devices and private keys were not compromised, and funds stored on Passport devices stayed safe.

Adding Ethereum support expands what users can do with Passport Prime. It also expands the number of transaction types, contracts and approval screens they need to understand before tapping “sign.”

What this means for hardware wallets and Ethereum users

The Ethereum Foundation funding a Ledger co-founder to build signing software for a competing hardware platform is a notable move. It suggests the Ethereum Foundation is interested in making secure signing available across multiple devices rather than leaving users dependent on a handful of vendors.

Sideloading adds friction, and friction tends to keep a product in the hands of enthusiasts rather than mainstream users until the official catalog arrives.

The catalog itself raises a governance question. Herbert described a system where trusted groups can send updates directly, so how Foundation decides who counts as trusted will shape both the security and the openness of the platform.

For Ethereum users, the near-term takeaway is practical. Anyone already holding a Passport Prime can test the beta signer now if they are comfortable sideloading, while everyone else may prefer to wait for the app catalog expected in winter 2026.