Extremely popular in Russia; great for specialized e-readers. MOBI/AZW3: Specifically for Amazon Kindle devices.

A subscription-based service for reading and listening. Google Play Books: Available for Android and web reading. Apple Books: Optimized for iPhone, iPad, and Mac. Free & Legal Archives

Avoid sites that require your phone number or "human verification" via SMS. 🎧 Alternative: Audiobooks

Best for mobile phones and most e-readers (Kindle excluded).