If you work as a cash handler, you may want to try out the U.S. Currency Education Program's Cash Assist Mobile app. This app gives helpful guidance on authenticating Federal Reserve notes*
Now available on the Apple App store for iOs devices, and the Google Play Store for Android devices, the Cash Assist app features interactive tools to assist in identifying counterfeit U.S. currency. Best of all, the app is free to download!
*Please note: Cash Assist does not identify counterfeits or authenticate bills for you.