SumatraPDF

What is SumatraPDF?

SumatraPDF is a free, open-source document reader for Windows built in C and C++. It supports PDF, EPUB, MOBI, FB2, CHM, XPS, DjVu, and comic-book archive formats (CBZ, CBR) in a single small executable that launches in under a second, even on older hardware. The project is intentionally minimal: it does not bundle a cloud service, an account system, OCR, or a ribbon of upsell features common to the commercial PDF readers it competes with.

Key features

• Multi-format: reads PDF, EPUB, MOBI, FB2, CHM, XPS, DjVu, CBZ, and CBR in one app, with per-format settings such as comic-book page view mode for CBZ/CBR.
• Fast and portable: ships as a single small .exe or a portable folder, no installer required, no admin rights needed, no telemetry, no ads.
• Annotations and highlights stored inside the PDF, with optional secondary sidecar .txt annotations.
• Customisable keyboard shortcuts, command-line interface, and a built-in ebook reader mode.
• Built-in PDF tools: re-flow text for tablet-style reading, favorite files and recent folders, full-screen presentation mode, and PostScript and image printing.

Comparison to paid PDF software

SumatraPDF is a lightweight alternative to Adobe Acrobat Reader, Foxit Reader, and Nitro PDF Reader. Where those products bundle cloud storage, account sign-ins, advertisements, toolbars, and large update installers, SumatraPDF is a single self-contained executable that does not phone home. The viewer supports advanced PDF features (links, forms, outlines, encryption) without any of the commercial readers' bloat. A separate companion utility, SumatraPDF Pro (commercial), adds advanced editing, OCR, and conversion, but the core viewer remains free.