OES is a standardized open-source platform for the creation and publication of online reference works in open access. The software is web-based.

OES is developed as a WordPress plugin and is built on the WordPress system architecture. This includes a WordPress installation with a relational database (MySQL) and support for PHP and HTTPS (e.g., via Apache). The software is divided into an editorial management system (provided via the WordPress interface) and a publicly accessible website (implemented as a WordPress theme).

For operating OES, the non-proprietary plugin Advanced Custom Fields (ACF) is required, which enables flexible configuration and structured data entry within the system.

The source code of OES is fully open and available on GitHub. More information about OES on GitHub.