GPC is a C-like language used to program Cronus Zen behaviour. You do not need to write it to use a script, but being able to read it changes how you evaluate one.
Ten minutes of reading tells you more about a script's quality than any feature list.
Editorial disclosure
peakgpc does not sell scripts, subscriptions, or hardware. We are an independent reference and analysis site. Rankings are based on published update cadence, configurability, documentation quality, and reproducible setup outcomes — not on vendor relationships. Where a library is purchasable, it is purchased from its own site, never from us.