Sumatra PDF - Sumatra PDF is a slim PDF/DjVu/EPUB/XPS/CHM/CBR/CBZ/MOBI viewer for Windows.
OpenAudible - OpenAudible Project Page
Google Docs Viewer - With Google Docs Viewer, you can quickly view many file types online, including PDFs, Microsoft...
DRmare Audio Converter - DRmare Audio Converter for Windows is a complete audio DRM removal tool designed to convert both protected audios, including Apple Music, Audible audiobooks, iTunes music, and common audios to MP3, WAC, FLAC, M4A, AAC, etc.
DjVuLibre - DjVuLibre: Open Source DjVu library and viewer
TunesKit Audible AA/AAX - Audible AA/AAX Converter by TunesKit is an application that enables you to convert audible AA and AAX files to the formats that are supported by other devices.