DeOlhoNaNota is a free Android application developed by PRODESP - Cia de Proc. de Dados do Estado de SP, belonging to the Utilities & Tools category. The app allows users to scan the QR Code on the Electronic Tax Receipt or Fiscal Electronic Consumer Note issued within the State of São Paulo using the phone's camera. It then verifies whether it was generated from the data of a SAT equipment regularly registered in the Department of Finance. The app also displays the main data of the purchase, making it a useful tool for consumers to check the authenticity of their receipts and prevent fraud. However, it should be noted that the app should not be used for reading other types of QRCode.

The SAT equipment is a new device that generates the Fiscal Electronic Coupon and transmits it via the Internet to the Department of Finance, replacing the Tax Receipt paper and fiscal printers. The app also reads the QR Code DANFE of Fiscal Electronic Consumer Note, in which case it displays all the purchase data. Overall, DeOlhoNaNota is a simple and easy-to-use app that helps consumers in São Paulo verify the authenticity of their receipts and prevent fraud.