Need to open a markdown file without launching a heavy editor? MarkViewer is a fast, lightweight markdown viewer built specifically for macOS. Double-click any .md file and start reading instantly.
Free • Offline • macOS 10.13+
You just want to read a markdown file. Maybe it's a README, release notes from GitHub, or local documentation. But to view it properly, you need to:
There should be a simpler way.
MarkViewer is a native macOS app designed specifically for viewing markdown files. No setup, no workspace, no complexity. Just double-click a .md file and it opens instantly.
Opens in under a second. No workspace loading, no extension initialization. Just your markdown file, rendered and ready to read.
Everything is processed locally on your Mac. No internet required. Your files never leave your computer.
Full support for tables, task lists, code blocks with syntax highlighting, and all standard markdown syntax.
Navigate long documents easily with an automatically generated table of contents from your headings.
No telemetry, no analytics, no cloud sync. Your markdown files are only read by you.
No paid tiers, no subscriptions, no hidden costs. Free forever.
Claude and ChatGPT output markdown files. MarkViewer makes reviewing and editing them effortless.
Claude stores project knowledge as markdown files. Download them and open in MarkViewer for offline access with auto table of contents.
Copy ChatGPT's markdown output, save as .md, and view with proper formatting. No more squinting at plain text in your browser.
AI-generated docs often need small tweaks. Make corrections with WYSIWYG editing and save. No IDE, no setup, just edit and go.
Most markdown reviewers are read-only. MarkViewer closes the loop: highlight a passage, leave inline feedback, and one shortcut sends an editable prompt to Claude, ChatGPT, Cursor, Gemini, or GitHub Copilot — no clipboard hijacking, no terminal injection.
WYSIWYG selection works across headings, lists, code blocks, and tables. No plugin setup.
Annotations are stored inline in the markdown as HTML comments, so they survive save/reload and don't affect rendering.
MarkViewer renders a prompt containing the file and every annotation. You can edit it, save it as your default template, or reset it.
Works with Claude, ChatGPT, Cursor, GitHub Copilot Chat, Google Gemini, Codex CLI, and any tool that accepts pasted text. MarkViewer only writes to clipboard on your explicit click.
Why it matters: AI assistants write drafts; humans review them. Until now, reviewing a Claude-generated README meant copy-pasting sections back and forth. The AI Review Loop keeps your annotations attached to the file and makes the handoff one keystroke.
Get the free app from the download section below and install it in your Applications folder.
Find any markdown file (.md or .markdown) on your Mac. Right-click it and select "Get Info" from the menu.
In the Info window, find "Open with" section. Select MarkViewer from the dropdown menu.
Click the "Change All..." button to set MarkViewer as the default app for all markdown files. Done!
Tip: Now double-clicking any .md file will open it in MarkViewer automatically. To open a specific file in another app, right-click and choose "Open With".
MarkViewer is optimized specifically for viewing markdown files. It launches instantly (no workspace setup), works 100% offline, and uses less memory. VS Code is better for editing code, but MarkViewer is ideal for quickly reading README files, documentation, or release notes.
Yes! MarkViewer includes a built-in WYSIWYG editor for quick edits. It's perfect for fixing typos, updating sections, or making small changes. For heavy writing or complex editing, consider using a dedicated markdown editor like Typora or Obsidian.
Absolutely! MarkViewer is perfect for reviewing markdown output from Claude, ChatGPT, or other AI tools. The auto table of contents helps you navigate long AI-generated documents, and WYSIWYG editing lets you make quick corrections.
Preview.app doesn't understand markdown syntax. MarkViewer renders markdown with proper formatting (headings, lists, code blocks, tables) and adds features like auto table of contents and WYSIWYG editing specifically for markdown files.
Your files never leave your Mac. MarkViewer processes everything locally with no internet connection required. There's no cloud sync, no account, and no file uploading. What's on your computer stays on your computer.
Yes! Download any README.md from GitHub and open it in MarkViewer. GitHub Flavored Markdown (tables, task lists, code blocks) is fully supported. Perfect for reviewing project documentation offline.
It's a workflow for reviewing markdown with AI assistants. Highlight any passage, press ⌘⇧R to leave an inline comment, then press ⌘⇧↵ to open an editable prompt panel. Copy the prompt into Claude, ChatGPT, Cursor, Gemini, or any AI tool. MarkViewer never writes to the clipboard without your explicit click.
Any chat or coding assistant that accepts pasted text: Claude, ChatGPT, Cursor, GitHub Copilot Chat, Google Gemini, Codex CLI, and local LLM UIs. The generated prompt is plain text, so you can edit it before sending and save your edits as the default template.
Different tools for different jobs. Here's where MarkViewer fits in.
💡 Our take: Use MarkViewer for quick previews and viewing. Use Typora if you're writing long-form content daily. Use VS Code if you're primarily editing code and need markdown support on the side.
Start viewing markdown files the simple way. Free for macOS 10.13 and later.
Download for Mac (Free)v1.0.34 • Universal Binary (Intel & Apple Silicon)
MarkViewer