Devices and methods for detecting credit card skimmers are provided herein. A device can include a printed circuit board having a pattern of electrical traces on its surface, and a computer readable medium comprising instructions that cause a processor to direct an electrical voltage to a trace and detect an electrical current between two points of the trace. A gap can be disposed between the two points across which a voltage is applied in order to detect a magnetic reader. A count of the detected magnetic readers within a credit card reading device may be indicative of the presence of a credit card skimmer.