ProcessWire

ProcessWire is a friendly and powerful open source CMS and CMF with an exceptionally strong foundation. With all custom fields, an easy-to-use jQuery-inspired API, and a powerful page selector engine, ProcessWire will rise to any task. Clients love ProcessWire for its no-fuss simplicity and ease of use when editing their site. Designers and developers love ProcessWire for its thoughtful, easy and powerful API-driven approach that keeps them in control of the markup and makes development fun again. Not to mention, ProcessWire's API can also be booted from other applications or command-line scripts, bringing entire new levels of accessibility to your content. ProcessWire is a modern SEO's dream come true. It uses logical, readable and search-friendly URLs that always reflect the content's home in the tree. Meaning you'll never have to worry about multiple URLs or play duplicate content games. With full markup control, all custom fields, and support for runtime URL segments, ProcessWire lets you take full advantage of all the on-site SEO possibilities without wasting your time on long irrelevant tags and tricks. ProcessWire is designed for the needs of today and not limited by the past. It is equally at home powering small-to-large scale standards-friendly websites, mobile websites, JSON/XML web services, Flash applications, AJAX-driven content, iPhone/Android applications, and more. This output agnosticism drives ProcessWire's simplicity and makes it support, rather than interfere with your work. ProcessWire may be relatively new to the open source world, but it's a mature product that comes from a strong bloodline of CMSs developed over nearly a decade. With many new features and enhancements since version 2.0, ProcessWire is now on version 2.5 (heading for 2.6 rapidly) and runs beautifully on web servers running PHP 5.3.8+ and MySQL 5 (with PDO database support).