QR Code

Beyond making addresses scannable, a QR code is a two-dimensional matrix of black and white squares that can hold roughly a hundred times more data than a traditional linear barcode, and it can be read instantly from almost any angle. The format was created in 1994 by engineer Masahiro Hara at the Japanese company Denso Wave, originally to track automotive parts on a Toyota supplier's factory floor. Denso Wave chose not to enforce its patent, which is a large part of why the format became a free, universal standard rather than a proprietary one.

In crypto, a QR code typically encodes a wallet address, but many apps use a URI scheme such as Bitcoin's BIP21, which bundles the address with a payment amount, a label, or a memo. Scanning the code lets a sending app auto-fill the recipient field, removing the risk of mistyping a long string of characters, since one wrong character sends funds to the wrong address permanently.

QR codes appear throughout crypto: exchanges show them for deposits, point-of-sale terminals use them for merchant payments, and hardware wallets display them to share a public address without exposing the device to malware over USB or Bluetooth. The main risk is that a code only shows a picture, not the destination itself, so a tampered or maliciously generated QR can redirect funds just as easily as a copied and pasted address. A QR code should never encode a private key or seed phrase; doing so would let anyone who scans it take full control of the funds.