What's the best Android app for reading PDF books offline?

PDF Reader is designed specifically for users who need consistent access to PDF content without internet connectivity. The app's core strength lies in its straightforward approach to document management - once PDFs are downloaded to the device, they remain accessible regardless of network conditions. This makes it particularly useful for commuters, travelers, or anyone in areas with spotty connectivity who want to read books, manuals, or lengthy documents without interruption.

Key features include a clean reading interface with configurable brightness controls, multiple viewing modes including single page and continuous scroll, and basic search functionality to locate specific text passages. The app handles document rendering efficiently, with minimal lag when flipping through pages even in larger files. While it doesn't include advanced annotation tools found in premium PDF editors, the reading experience remains smooth and responsive.

Some users note that the free version displays occasional banner ads, though these don't significantly interfere with reading sessions. The app maintains a small storage footprint and doesn't require excessive permissions, focusing primarily on its core function as a reliable PDF viewer. For basic reading needs where annotation isn't a priority, PDF Reader delivers consistent performance across various Android devices.