gander

Gander is a MIT-licensed Android file viewer intended to open many common file types in one app. It supports PDF, DOCX Word files, XLSX, XLS, XLSM, XLSB, CSV, and ODS spreadsheets, PPTX presentations, JPG, PNG, WebP, BMP, HEIC, GIF, SVG, AVIF, and ICO images, MP4, MKV, WebM, AVI, and other video formats, MP3, FLAC, WAV, Ogg, Opus, and other audio formats, plus Markdown, text, logs, JSON, XML, and source code files. Legacy DOC and PPT are not supported. The app renders locally using bundled components such as pdf.js, docx-preview, SheetJS, PPTXjs, Media3 ExoPlayer, marked, and DOMPurify. Files are received through Android Storage Access Framework grants and Open With intents, so Gander does not request storage or Internet permission. Office and web-style content is displayed in a sandboxed WebView with local asset loading. Viewer features include pinch zoom, smooth scrolling, tiled decoding for large photos, recent files with thumbnails, folder browsing through one-time grants, share-sheet integration, document search with match navigation, PDF text selection and screen-reader support, PDF page-position memory, PDF night mode, file sharing, and jumping to a file's location. Unknown or extensionless files can be inspected as text, with large text files loaded in chunks. The interface uses Material 3 and supports dark mode and edge-to-edge layout. It requires Android 8.0 or newer; PDF viewing requires Android System WebView 125 or newer. The README provides APK installation instructions, release-signature verification with apksigner, Obtainium update guidance, and Gradle build commands using JDK 17 or newer and Android SDK platform 36. It also describes an About screen showing the app's requested permissions and bundled library licenses.