The MPLAB XC8, XC16 and XC32 compilers offer three cost-effective optimization levels; free, standard and pro; the Pro editions can be evaluated for free for sixty days. The software is available for download free of charge at www.microchip.com/mplabxc. The edition customization is applied by using an activation key. Without a key, the installation defaults to the free edition. The standard (STD) edition offers about 25% improvement in code size compared to the free edition, and the pro edition offers the greatest optimization. Evaluation is an option that users can activate only one time at their own discretion. Eval offers pro functionalities for sixty days from the time user activates it; after sixty days, the compiler will default back to the free edition. Since users can activate the eval option at any time, but only once, it is suggested that they develop and debug code first using the free edition, and activate the eval option only when the code is nearly complete.