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