Open-source hardware tools, like the Bus Pirate and similar devices, are designed for probing, testing, and interacting with hardware systems at a low cost. These tools allow users to interface with various communication protocols, such as UART, SPI, or I2C. Open-source hardware tools are typically much cheaper than commercial devices. This affordability makes them accessible to a wider range of users, from beginners to professional security testers, without sacrificing functionality.