Peekdown: Markdown Viewer

Quick Look, Edit & Annotate Peekdown is a Markdown viewer and editor for macOS. It renders your files the way GitHub does — tables, code blocks, task lists, footnotes, LaTeX math, and Mermaid diagrams — and because it's native, your files open instantly. Open a file to read it, or press Space in the Finder to view it fully rendered in Quick Look. Copy a code block or the whole document from either one. Keep your files in the sidebar. Create a Space, give it a name, color, and icon, then drag in the files and folders you want grouped together — and create new ones without leaving the app. Everything you open collects in a Recents list shared across windows. Annotate AI Output: select any rendered text and mark it up — strike, comment, highlight, lock, add a document note, or attach block notes to individual sections — then copy your annotations as a structured prompt for any AI assistant. Your doc auto-reloads when the file changes externally, so you're always reviewing the latest version. You can even see what changed in a +/- diff view. The built-in editor gives you side-by-side editing with live preview, synced scrolling, and syntax highlighting for 100+ languages. - Sidebar with Spaces: your own named, color-coded groups of files and folders - Recents list shared across every window - Renders GitHub-Flavored Markdown, MDX, and Obsidian syntax - LaTeX math and Mermaid diagrams, rendered offline with no plugins - Quick Look previews with the same GitHub formatting - Annotations visible in Quick Look previews - Annotate and copy as a structured prompt for any AI assistant - Obsidian vault support: callouts, highlights, wikilinks, tags, embeds - Side-by-side editor with live preview and scroll sync - Interactive checkboxes that save on every tick - Copy any code block or the whole file - Pin on top to keep docs visible while you code - Footnotes with superscript links - Syntax highlighting for 100+ languages with 8 themes - Light and dark modes that follow your system - See what an AI tool or another app changed, in a +/- diff - Auto-reload, window tabs, find & replace, and more