Crypto Key Stack

Crypto Key Stack was a physical seed phrase backup product developed by Chicago-based Crypto Key Stack LLC, co-founded in 2018 by Chris Gonyo and NFL veteran Israel Idonije. The product was designed to address a gap in cryptocurrency security: hardware wallets protect private keys from online threats, but a paper seed phrase backup remains vulnerable to fire, flooding, and physical damage. The founders set out to offer an affordable stainless steel alternative that users could set up entirely offline, without trusting any third party with their recovery data.

The core product was a credit card-sized stack of black anodized stainless steel plates. Each plate held one 24-word BIP39 mnemonic seed phrase, and up to ten plates could be assembled into a single stack, making it possible to back up multiple wallets with one device. An electric engraver was included so users could inscribe their recovery phrases letter by letter directly into the metal. The plates were rated to withstand temperatures up to 2,200 degrees Fahrenheit, well above the heat of a typical house fire, and were also waterproof and rustproof.

Crypto Key Stack was compatible with the recovery seeds generated by mainstream hardware wallets including Ledger, Trezor, and KeepKey, as well as software wallets such as MetaMask and JAXX. Because the product stored seed phrases rather than acting as a wallet itself, it was chain-agnostic: any wallet whose recovery phrase followed the standard BIP39 format could be backed up using the plates.

Independent durability testing found the product performed well under crush and heat stress, though reviewers noted that the small screw hardware and the limited resolution of the included engraver made it possible to produce ambiguous characters, such as B versus 8 or 1 versus l. Expansion plates were sold separately, allowing users to add capacity without replacing the entire stack.

Crypto Key Stack is no longer in operation. The company website went offline in April 2025, and the company is listed as deadpooled. The product continued to appear through third-party retailers after the main site closed.