Dollar Blacklist | Check whether a USD bill is genuine or counterfeit.

Many people don't really know how to spot fake bills by inspecting their security features. The official website of the US currency does list them in several PDF files, but that's not the most practical way to learn all the security features from all the denominations from all the series years. This app is basically a tool that lists the security features of USD notes, but it's also a reputation system that warns when a given banknote was marked as counterfeit by a previous user. ...But counterfeit bill detectors already exist and they don't fail, so what's the problem it solves? Those machines are actually unnecesary; counterfeiting every security feature in high quality is very expensive and usually not worth the face value of the counterfeited bill. So most of the times it's enough to look carefully at the security features, but there are so many, and they vary from denominations and series year, and the governments includes new features every few years. I'm not sure if countefeit bill detectors can be updated like mobile applications in order to analyse the newly included features. That's one problem of those machines. I'm also not sure if counterfeit bill detectors are able to work with other currencies like the australian dollar or the british pound. Probably not, and if some do, they'll be more expensive. That's another issue. The last problem has to do with the portability and accessibility: most counterfeit bill detectors don't fit in the pocket and they may be expensive. So those are the main issues this app aims to solve.