OpenAudible - OpenAudible Project Page
Smart AudioBook Player - Smart AudioBook Player app comes up with features to help you in casting all your audiobooks to Chromecast enabled devices so you can enjoy them with your friends and family members.
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.
Prologue - Audiobook player on iOS for Audiobooks hosted on a Plex media server
AudKit AAX Converter - Full-featured AudKit Audible AAX converter to download and convert Audible audiobooks to MP3, AAC, M4A, M4B, etc. losslessly.
Voice - Convert texts to audio files easily... Write your text, click export.