| Title | CMS Category |
|---|---|
| osCommerce | Ecommerce |
| OsClass | Specialized CMS |
| OroCommerce | Traditional CMS CRM Solutions Ecommerce DAM Software |
| OrangeScrum | Groupware Wiki Software |
| OpenWGA | Enterprise Solutions |
| OpenProject | Groupware |
| OpenMRS | Specialized CMS |
| OpenEMR | Specialized CMS |
| OpenEMM | CRM Solutions |
| openCRX | CRM Solutions |
| OpenCMS | Traditional CMS |
| OpenCart | Ecommerce |
| Open-Realty | Specialized CMS |
| Open Web Analytics | CRM Solutions |
| Open Exhibits | Specialized CMS |
| Open eShop | Ecommerce |
| Open eLMS | E-Learning |
| Open edX | E-Learning |
| Onveos | Ecommerce |
| OnSpace | App Builders |