Playing cards for nerds.

A pack of 54 playing cards where each card is written as a short block of JSON, the text format computers use to store and share data, instead of the usual pips and pictures. Each card just says what it is: its rank, its suit and its type. They're designed in London by Dan Berg.

Yes. It's a standard pack of 52 cards plus two jokers, and every card still tells you its number and suit. Snap, rummy, poker, patience - anything you'd play with a normal pack.

No. Each card spells out its rank and suit in plain words, so anyone can read it and play. The jokers are written as a hacking attempt, which is an extra joke for anyone who works with computers.

It's a free web app that runs in your phone's browser, so there's nothing to download. Point your camera at a card and it shows you the traditional card that the data describes.

Try the card reader

Yes. The deck started on Kickstarter as Pure Code Playing Cards and was funded in March 2026, when 287 backers took it to 719% of its target. It was renamed after people pointed out that JSON is data, not code.

For anyone who works with computers, or anyone who likes cards, yes. It comes in a silver-foiled tuck box, so it's ready to give.

Yes. This is the first edition, printed as a limited run.

A real calibration label, the kind you'd find on electronic equipment, filled in by hand. Dan signs it, dates it on dispatch and sets the next calibration for ten years later, and it goes on the tuck box. It's a limited edition: only 50 will ever exist, and you can add one when you buy.

Delivery is free in the UK. Everywhere else it's free when you buy 2 or more packs; for a single pack there's a flat delivery charge for your country, shown under the buy button and added at checkout.

Yes. You have 14 days from receiving your pack to ask for a return, as long as it's in the condition you received it.