CRYPTO GUIDANCE INC.

Kansas City, MO

What Is an Air Gap?

Published 2026-08-15. Last updated 2026-08-15. Written by John Alewine, Crypto Guidance Inc.

An air gap means the machine that can spend your coins does not have a network connection, and you do not plug it into a machine that does. Data crosses the gap as a file or a QR code, not as a live USB conversation with your infected laptop. A Coldcard used with an SD card is the example I can point at. A hardware wallet permanently glued to Ledger Live over USB is convenient, and it is a thinner gap.

Who This Is For

People holding an amount they would not want sitting next to a browser. It is not required for a first $100 of bitcoin. It is the threat model behind "I am done being one malware click away."

How It Actually Works

Computer builds a PSBT. You walk the file to the offline signer. You walk a signed file back. The computer broadcasts.
Creating the seed should happen on the offline device, not in a website, not in a phone app that later "became" watch-only. See the restore test.
QR air gaps (animated QR between phone and device) are still an air gap if the signer has no radio. Verify addresses on the device screen either way.

Risks I See in Sessions

"Air-gapped" firmware updated over the same USB they swore they would never use. Occasional updates happen. Make them intentional, from official files, not a surprise cable.
A signer that has Wi-Fi "just for the price ticker." That is not an air gap. That is a phone with extra steps.
Photographing the seed so the gap is easier to bridge. You just put the private side on a networked camera roll.

When It Matters

Savings, inheritance, and any stack you would not keep in a hot wallet. The Security page is the spine. Coldcard plus Sparrow is one finished implementation, not the only one.