Getting Started

Peekdown is a markdown viewer and editor for macOS that renders your files with GitHub-style theming. It works entirely offline — no accounts, no internet connection, no telemetry.

Opening Files

There are several ways to open a markdown file:

  • ⌘O — Open a file from the file picker
  • Drag and drop — Drag a file onto the Peekdown window or Dock icon
  • Finder — Double-click a markdown file (if Peekdown is set as the default app)
  • Open Recent — Use File > Open Recent to reopen a previously viewed file or folder

You can also open files from the terminal:

open -a Peekdown /path/to/file.md

Supported File Types

Peekdown supports the following file extensions:

  • .md
  • .mdx
  • .markdown
  • .mdown
  • .mkd
  • .txt (rendered as plain text in a monospace font)

Peekdown renders GitHub-Flavored Markdown (GFM), which is a superset of CommonMark. This includes tables, task lists, strikethrough, and fenced code blocks with syntax highlighting. Beyond GFM, Peekdown renders ^text^ as superscript, plus LaTeX math and Mermaid diagrams — see the Editing topic.

Setting Peekdown as the Default App

To open all markdown files with Peekdown by default:

  1. Right-click any .md file in Finder
  2. Select Get Info
  3. Expand the Open with section
  4. Choose Peekdown from the dropdown
  5. Click Change All…

Copying a Document

The copy button in the title bar puts the whole document on the clipboard. A normal click copies the markdown exactly as written.

Hold Option and click to copy just the text instead — no # in front of headings, no ** around bold, and links come through as the words you see rather than the URL. That's the one you want when you're pasting into something that doesn't understand markdown.

System Requirements

Peekdown requires macOS 15.0 (Sequoia) or later.