ImageGlass vs Mozilla PDF.js

ImageGlass is a desktop image viewer for browsing and viewing image files on Windows, macOS, and Linux. It supports more than 90 formats, including WEBP, GIF, SVG, PNG, JXL, HEIC, and RAW. Viewing tools include slideshows, thumbnails, color picking, hardware-accelerated rendering, and EXIF information through ExifGlass. Built-in edits cover rotation, flipping, cropping, lossless compression, and resizing. Pro adds an HDR Tone Mapper, free and margin panning, File Watcher, custom mouse clicks, and settings and feature locks. The app can associate external editing apps, use custom hotkeys with them, and accept extensions built with its SDK. ImageGlass says it does not scan image libraries for analytics or send images, filenames, or folder paths elsewhere. Classic is free. Pro Individual is $14.90, paid once purchase; Pro Team is $69, paid once purchase. Pro Business is $9,917 a year. The 14-day Business trial requires no account, online activation, or device lock for local license verification.

Mozilla PDF.js is a free, web standards-based platform for parsing and rendering PDF files. Developers can use its display API to render documents and retrieve information, or adapt the viewer layer for a custom interface. That viewer is used in Firefox and project browser extensions. PDF.js renders annotations and supports adding a subset of annotation types, and it supports form filling; OCR is not provided. The project targets HTML5-compliant browsers and includes a legacy build for older browsers, although PDF feature support varies by browser and version. Prebuilt builds are available, with hosted copies listed through jsDelivr, cdnjs, and unpkg. Developers can clone and build it locally, but some browsers require a local web server instead of opening PDFs through file URLs. Cross-origin requests are blocked by default, so CORS or a server proxy may be needed. For large documents, rendering only visible pages can reduce memory use. PDF.js is licensed under Apache 2.0.