OneMarkup: File Editor

Open, preview, edit, save, and share Markdown, HTML, SVG, JSON, YAML, XML, SRT subtitle, and other text-based files from Files, Mail, WeChat, and other apps. Everything stays on your device and works offline. Switch among a safe visual preview, the original source, and an editor. Search inside files, adjust text size, follow light or dark appearance, and share your edited copy. JSON and XML appear as structured views, YAML gets readable line numbers, and SRT files become timed cue cards. Your first edit creates a clearly labeled working copy in OneMarkup’s Files-visible Documents/Edits folder, then saves later changes automatically. The original remains untouched, and Recents keeps originals and edited copies separate. Need a quick look? Add “Quick Preview Here” to the iOS share sheet to inspect supported files without leaving the current app. Previewing keeps a deliberate safety boundary: scripts are off by default, remote resources stay blocked, and HTML or SVG cannot navigate unexpectedly. OneMarkup is free and account-free, with no ads, analytics, tracking, or in-app purchases.