OnyX is the main application. The Maintenance and Deeper applications are parts of OnyX. Maintenance is similar to the OnyX Automation pane, and Deeper is similar to the OnyX Parameters pane.
Then if you use OnyX, the Maintenance and the Deeper applications are redundant!
Show all the last modifications, the new features, and the resolved issues for the latest stable version and the version in progress.
OnyX is translated into several languages by volunteer users and some professionals offering services localizations.
Here are links to sites that would be useful to bookmark.
"Thank you" to them for their help during all these years.