Update README.md

README.md

@@ -935,6 +935,7 @@ _Games, game servers and control panels._
 - [Canvas LMS](https://www.canvaslms.com/) - Canvas is the trusted, open-source learning management system (LMS) that is revolutionizing the way we educate. ([Demo](https://canvas.instructure.com/register), [Source Code](https://github.com/instructure/canvas-lms)) `AGPL-3.0` `Ruby`
 - [Chamilo LMS](https://chamilo.org/) - Chamilo LMS allows you to create a virtual campus for the provision of online or semi-online training. ([Source Code](https://github.com/chamilo/chamilo-lms)) `GPL-3.0` `PHP`
 - [edX](https://www.edx.org/) - The Open edX platform is open-source code that powers edX.org. ([Source Code](https://github.com/edx/)) `AGPL-3.0` `Python`
+- [Gibbon](https://www.gibbonedu.org/) - The flexible, open source school management platform designed to make life better for teachers, students, parents and leaders. ([Source Code](https://github.com/GibbonEdu/core)) `GPL-3.0` `PHP`
 - [ILIAS](http://www.ilias.de) - ILIAS is the Learning Management System that can cope with anything you throw at it. ([Demo](http://demo.ilias.de), [Source Code](https://github.com/ILIAS-eLearning/ILIAS)) `GPL-3.0` `PHP`
 - [Mahara](https://mahara.org/) - Open Source fully featured web application to build students electronic portfolio. ([Source Code](https://github.com/MaharaProject/mahara)) `GPL-3.0` `PHP`
 - [Moodle](https://moodle.org/) - Moodle is a learning and courses platform with one of the largest open source communities worldwide. ([Demo](https://moodle.org/demo/), [Source Code](https://git.moodle.org/gw)) `GPL-3.0` `PHP`