Affordable electronics for instrumentation play a vital role in academia since research budgets are tight nowadays. In this paper a low-cost open-source high-frequency portable Raspberry Pi-based pulse counter is presented. Although it is designed as a 2 channel counter, it can be easily modified to a 4 channel counter. It provides a relay control interface for experimental-setup integration and counts pulses up to 10 MHz frequency. Presented system is proved to be accurate by an Xray transmission rate measurement experiment.