FastStone Image Viewer vs SumatraPDF

FastStone Image Viewer is a Windows image browser, converter, and editor for individual images and collections. Editing tools include resizing, rotation, cropping, color adjustment, sharpening, blur, Clone Stamp, and Healing Brush. It supports major graphic formats and popular camera RAW formats, including HEIC, WEBP, PDF, SVG, and JPEG XL. The Compare Images feature displays up to four pictures side by side, while batch tools convert and rename collections. Slideshows offer more than 150 transition effects and music. The program can acquire images from scanners and batch scan to PDF, TIFF, JPEG, or PNG. Users can launch external editors from within Image Viewer, and a portable version can run from removable storage. FastStone lists personal and educational use as free and a commercial lifetime license at $34.95 as a one-time purchase, with upgrades free. Another plan listing gives a price of $34.95 a month, so the commercial license terms should be confirmed before purchase. The product is listed for Windows, and FastStone provides technical support by email.

SumatraPDF is a free, open-source Windows reader for PDFs, ebooks and comics. It opens PDF, EPUB, MOBI, CBZ, CBR, DjVu, XPS, CHM and common image formats. Document tools include annotation editing, form filling, signing, merging, splitting, extraction and conversion. The app supports text-to-speech, Windows UI Automation screen readers and keyboard-only use. Users can customize keyboard shortcuts, themes and toolbar layout. A portable edition runs without installation, including from a USB drive. Windows 7, 8, 10 and 11 are listed, with 32-bit, 64-bit and ARM64 builds. Documents and their names are not uploaded, although recently opened files remain in a local settings file. Update checks contact the maker’s server, and official builds send crash reports that may include document fragments. SumatraPDF has no OCR support and is not available for Mac or Linux.