ШирМа is an Android app designed to detect counterfeit banknotes of 500, 1000, 2000, and 5000 Russian rubles by comparing their serial numbers. Users can scan the banknotes using their mobile device's camera or manually enter the serial number. If a scanned banknote's serial number matches the data stored in the app's memory, the app displays a warning message stating that the probability of the banknote being counterfeit is high. In such cases, users should manually check the banknote by entering the serial number themselves. The app's functionality includes entering the letters in the same format as on the banknote, taking into account uppercase and lowercase letters. It is essential to note that the app only recognizes the serial number and does not scan the paper or watermark. Therefore, do not use the app to check copies of genuine banknotes or souvenir products that are not payment instruments. The app works best in well-lit environments, and the database updates as of December 20, 2021.