The source code of the free version (GPLv2+ license) can be found in a public GitHub repository.

Any help in improving the Plugin is truly appreciated. If you would like to contribute in development you need to be familiar with Git(Hub), WordPress Coding Standards and modern WordPress development (i.e. Gutenberg).

Translations

You can also help translating the Plugin to your language via https://translate.wordpress.org (WordPress.org user account required!)