It is written in Java and built on the Eclipse Rich Client Platform which uses SWT as a widget toolkit to allow it to fit in with the look and feel of different operating systems while remaining cross-platform.

[9] Version 1.2 improved toolbar customization and added support for Atom 1.0 News feeds.

[10] Versions 1.2.1 and 1.2.2 added universal binary support for the Mac as well as drag and drop for tabs and a built-in feed validator.

[14] Version 2.0 was rebuilt on the Eclipse Rich Client Platform and used db4o for database storage and Lucene for text searching.

RSSOwl has been translated into many languages, including Bengali, Bulgarian, Czech, Chinese (Simplified), Chinese (Traditional), Danish, Dutch, English, Finnish, French, Galician, German, Greek, Hungarian, Italian, Japanese, Korean, Norwegian, Polish, Portuguese, Russian, Serbian (Cyrillic), Serbian (Latin), Slovenian, Spanish, Swedish, Thai, Turkish, and Ukrainian.