Hi HN, I built an Android file viewer that opens PDF, Word, Excel, PowerPoint, images, video, audio, Markdown and code, and asks for no permissions at all. I have always been uneas…

Take a gander at any file. A tiny, open source, fully offline file viewer for Android that opens PDF, Word, Excel, PowerPoint, photos, videos, audio, Markdown, text and code in one app, with zero permissions, no ads, no tracking and no internet access at all. Every phone ships with a dozen half-viewers that bounce your documents to cloud services. Gander is the opposite: one small APK (about 15 MB) that renders everything on the device. It cannot phone home because it does not even hold the INTERNET permission. Legacy binary .doc and .ppt are not supported (no faithful offline renderer exists); the app explains this and suggests re-saving as .docx / .pptx. Binary .xls works. Updating: install the new APK over the old one; recents and folder grants survive. Automatic updates without a store: install Obtainium and add https://github.com/mokshablr/gander as an app source. It follows the tagged GitHub releases here and updates Gander like a store would. Verify before installing: every release is signed with the same key, so you can confirm an APK really came from this repo. Obtainium can pin the fingerprint below, and for a file you have already downloaded: Gander receives files through the Storage Access Framework and "Open with" intents, so the OS hands it exactly the documents you chose and nothing else. Office formats render inside a locked-down WebView whose every request is intercepted by WebViewAssetLoader: bundled JS libraries load from app assets and the document streams from the content URI. No network stack is ever touched, and the app does not declare the INTERNET permission, so there is nothing to audit or trust. Folder browsing uses ACTION_OPEN_DOCUMENT_TREE grants. Note that Android itself refuses to grant the Downloads root to any app; grant Documents, DCIM or a subfolder of Downloads instead.