'Open Hardware Wallets Could Drive Self-Custody Adoption,' Says Keycard’s Guy-Louis Grau

Key Takeaways

Keycard says self-custody still needs better hardware because many current options keep users in closed ecosystems.
Its solution is an open, modular smart card system that keeps keys on the card while working with multiple wallets.
Grau says user experience is still the biggest barrier, especially when people cannot clearly see what they are signing.
Keycard’s bigger goal is to grow an open self-custody ecosystem that could also support crypto-native payments.

As crypto continues to grow mainstream, hardware wallets are set to become more than niche devices for security enthusiasts.

At EthCC in Cannes, CCN’s Giuseppe Fabio Ciccomascolo spoke with Guy-Louis Grau, project lead of the open-source, self-custodial hardware wallet Keycard, who argued that the crypto industry still relies too much on closed hardware, closed software, and companion apps that keep users trapped inside one controlled environment.

That is the problem Keycard is trying to solve. Rather than building another locked-down hardware wallet, Grau said his goal is to create a more open and modular system, one where your keys stay protected in the hardware while providing you with complete control on how to use them.

Modernizing Hardware Wallets

Grau emphasizes Keycard’s mission around a basic belief: that self-custody wallets need a dedicated hardware layer to combat the “insecure environment” provided by mobile or desktop wallets.

But the tradeoff is that many hardware wallets are too closed by design:

“We think that hardware wallets are too closed-source, and they try to lock-in users within one environment. You’ve got the companion app, where their behavior can be monitored and where things can be sold to them. The goal of hardware wallet companies is to make money.”

Grau, on the other hand, hopes Keycard can make hardware wallets “as open as possible and as modern as possible” as, in the end, open hardware puts control in the hands of the user.

That open approach emanates throughout Keycard. Grau said Keycard publishes its software, hardware, and even its mechanical development openly, treating the product as infrastructure that others, even its competitors, can build on too.

The Security Model is Simple: Keys Stay on the Card

Keycard keeps your keys on its slim, card-shaped hardware wallet, and they never leave it. This approach, Grau suggested, creates a cleaner security model than systems where a card acts more like a backup, or where keys can move between devices:

“With a Ledger, you have a card, you tap it, and the keys go from the card to the Ledger. With Keycard, your keys always remain on the card. Then, it’s all about control. When you have that, you decide how you use it.”

He described Keycard as a smart card built around Java Card technology, the same general class of technology used in widely deployed secure cards.

One Card, Multiple Wallets

Garu noted that Keycard already works with more than 15 wallets across different ecosystems, and he emphasized that none of them are Keycard’s own wallet:

“MetaMask, Rabby, for Bitcoin it’s Sparrow or Specter, there are more than 15 compatible with this ecosystem. So you choose.”

He described a setup where you can tap your card against a mobile wallet to sign transactions, or use it with a desktop wallet through a smart-card reader. That interoperability is also part of how Grau tries to distinguish Keycard from its rivals:

When asked about what makes Keycard stand out from its competitors, Grau said “We’re fully open source and modular. Anyone can audit the product to make sure we’re doing what we claim. More generally, our cards are doing the same thing as our competitor, but it can evolve into more things because lots of other projects can build around it.”

Shell Pushes The Idea Further With Clearer Transaction Review

Grau also used the interview to highlight Shell, a product that turns the card into a more traditional hardware wallet experience without changing the underlying security model.

His point?

That while a card like Keycard is useful by itself, it does not show users what they are signing. This creates a trust gap, because the user still has to rely on the phone or a desktop interface.

Shell is the solution:

“If you want to check your transaction in a secure environment, you put the card in, enter your PIN, and use Shell’s camera to scan transactions through a QR code. So it turns your card into a hardware wallet.”

In his telling, the process remains air-gapped because there is no Bluetooth or Wi-Fi involved in the signing flow. He continues:

“You scan the QR code, you get a transaction to review. If you’re happy with it, you sign it, and send it back to MetaMask where it gets sent to the blockchain.”

This matters most once users move beyond simple crypto transfers and start interacting with more complex on-chain actions. In those moments, Grau suggested, there’s a difference between “I signed a transaction” and “I understood exactly what I signed,” which can become a real security problem:

“It’s not really acceptable to sign something without being sure of what it is you’re doing. Are you signing your transfer of ten BTC to someone or are you accepting a transaction that will drain you of everything?”

The Main Barrier is Still User Experience

Grau was direct about what still holds self-custody back, and that’s complexity. He said the real setup experience for hardware-based self-custody is still too painful for many users, and it remains one of the biggest limits in terms of adoption.

Such complexity is part of why Keycard’s user base is largely crypto-native users who already understand the pain points of existing hardware wallets, Garu admitted, but also those who want something more flexible or more open.

At the same time, Garu argued that Keycard’s simplified backup options and the ability to hold multiple cards could remove the friction users face when managing multiple wallets or seed phrases across different devices. Still, he was clear that this isn’t a mass market solution just yet, instead presenting self-custody as a spectrum that will keep evolving as decentralized systems grow.

“All these decentralized systems, they need to shift how you think about access, you know? No more logins and passwords. Since it’s decentralized, users need to own their keys and hold custody. So as decentralized systems grow, so will the need for self-custody. So we think we are just in the early days of self-custody, and there will be a need for every type of self-custody over time.”

What Comes Next for Keycard

Looking ahead, Grau said Keycard’s near-term focus is straightforward: grow awareness, add more partners, and expand the ecosystem around open standards. He said the company wants more wallets to support the system, and stressed that even competitors are welcome if they help grow that wider open environment.

Beyond this, he pointed to what he sees as a natural next step for Keycard in crypto-native payments:

“There are tons of crypto cards, but actually they all rely on Visa/MasterCard networks. But once you have your private keys inside Keycard, it makes sense to use these keys for native payments.”

This ambition fits Grau’s broader argument in not just building a safer hardware wallet, but a more open system for self-custody that gives users direct control over how they store, sign, back-up, and even spend their crypto.