ProcessWire is a free PHP open source CMS with a great API built to save you time and make development fun at any scale. Developed by Ryan Cramer Design, LLC
License: Open Source
ProcessWire is a flexible and customizable CMS geared towards developers who want to build tailored solutions, whereas Concrete5 offers a more user-friendly experience with built-in e-commerce and visual editing features, making it ideal for users with less technical knowledge.