Apps to Low memory usage

PDF-XChange Viewer is a versatile and lightweight PDF reader and editor. It offers a wide array of features for viewing, annotating, and manipulating PDF documents, including OCR capabilities and form filling, all within a user-friendly interface.

Evince is a lightweight and versatile document viewer designed for various formats including PDF, PostScript, DjVu, TIFF, XPS, and DVI. It provides a clean and intuitive interface for easily accessing and navigating your documents.

Apache HTTP Server, widely known as Apache, is a robust, open-source web server software that has been the backbone of the internet for decades. It is highly configurable and extensible through its modular architecture, supporting a vast array of features for hosting websites and web applications.

Sumatra PDF is a free and lightweight PDF reader for Windows, renowned for its speed and minimalist interface. Beyond PDF, it supports a variety of other formats including EPUB, MOBI, CBR, CBZ, XPS, and DjVu, making it a versatile e-reader.

Foxit Reader is a robust and feature-rich PDF reader and editor that provides users with a comprehensive set of tools for viewing, annotating, signing, and creating PDF documents. Known for its blend of performance and functionality, it caters to both casual users and professionals handling complex PDF workflows.

GoodReader is a powerful document reader and file manager for iOS, excelling in handling large PDF files, annotations, and secure cloud integration, ideal for professionals and students needing robust document management on the go.