to discuss products and purchases in real-time. However, the transmission of digital receipts is still a problem, since often Internet connectivity is not available at the point of sale which hampers a real-time interaction. To overcome this problem with current technology, this paper presents a way to efficiently transmit a complete receipt in a QR-code, a certain kind of 2D matrix code (often also called “2D barcode”). Thereby, only a smartphone equipped with a camera is needed and Internet connectivity is not a problem anymore. However, due to size constraints, the encoding of a full receipt needs to be as efficient as possible. We present a custom, domain-specific encoding that was developed exactly for this purpose and show that our prototype implementation performs better than sophisticated, general purpose compression algorithms on this kind of data.