v0.2.2 · macOS 12+ · free forever MDHero — free markdown viewer and editor for Mac

The markdown viewer and editor
your Mac deserves.

A free, open source markdown viewer for Mac and a lightweight editor — fast, focused, and built for Apple Silicon.

Under 8MB. The free markdown viewer Mac users keep installing instead of TextEdit. Universal binary for Apple Silicon and Intel. Open any .md file with a double-click, then hit ⌘E to edit and ⌘S to save — no accounts, no uploads.

Download for macOS View source
Requires macOS 12+. Universal binary — runs natively on M1, M2, M3, M4 and Intel Macs.

Why Mac users choose MDHero as their markdown viewer for Mac

A native macOS markdown viewer that feels like a Mac app should

Universal binary for Apple Silicon (M1–M4) and Intel. Under 8MB — lighter than a single Keynote template. The native markdown viewer launches in under a second and barely touches your Activity Monitor.

Retina-sharp rendering

San Francisco-friendly typography, syntax colors for 25+ languages, KaTeX equations, and Mermaid flowcharts. Appearance follows your macOS dark mode setting automatically.

Paste from ChatGPT or Claude

LLM paste mode cleans up the escaped newlines and stray backslashes that break formatting when you copy AI output. Paste, render, read.

Edit in place with ⌘E

Press ⌘E on any local file to flip into a focused editor. ⌘S saves to disk. Scroll position follows you between viewer and editor — line by line.

Navigate like you're in Xcode

⌘T for new tabs, drag to reorder, ⌘F to search. Table of Contents sidebar, pinned project folders, and optional Vim keybindings for terminal-native developers.

Double-click any .md in Finder

Register MDHero as your default markdown handler. Open local files, GitHub URLs, Claude Code plans, or paste raw markdown — one app handles all of it.

No cloud, no telemetry

Everything stays on your Mac. No file uploads, no account creation, no data collection. Works fully offline — open a file in airplane mode and it just works.

How MDHero compares on macOS

There are many great markdown tools for Mac. Here's how MDHero fits in.

MDHero Marked 2 MacMD Viewer Typora QuickMD
Price Free $13.99 $19.99 $14.99 Free
Open source Yes No No No Yes
App size ~8MB ~30MB ~15MB ~90MB ~10MB
Built-in editor Yes No No Yes No
Mermaid diagrams Yes No Yes Yes Yes
KaTeX math Yes Yes Yes Yes Yes
LLM paste mode Yes No No No No
Windows support Yes No No Yes No
Install · macOS

First launch takes one click. After that, it just works.

MDHero is open source and not signed with an Apple Developer ID (Apple charges $99/year for that, which we haven't taken on). On first launch, macOS shows a security dialog. Here's how to get past it once.

Method 1 — System Settings no Terminal

  1. Download MDHero_0.2.2_aarch64.dmg and open it
  2. Drag MDHero to your Applications folder
  3. Double-click MDHero — you'll see "MDHero" Not Opened. Apple could not verify…
  4. Click Done
  5. Open System Settings → Privacy & Security
  6. Scroll to the security section. You'll see a message about MDHero being blocked. Click Open Anyway
  7. Enter your Mac password and confirm
  8. MDHero launches. From now on, double-clicking just works.

Method 2 — Terminal one command

If you're comfortable in Terminal, run:

xattr -cr /Applications/MDHero.app

Then double-click MDHero. It launches with no further prompts.

What's safe about this?
  • MDHero is fully open source — every line of code is on GitHub.
  • The build is automated on GitHub Actions from public source — no manual steps where something could slip in.
  • Releases are downloadable directly from GitHub, not a third-party mirror.
  • The Gatekeeper warning is identical to what you'd see for thousands of legitimate open-source Mac apps that don't pay Apple's developer fee.

More on viewing markdown on Mac

Guides, comparisons, and quick tips from the MDHero blog.

Guide

How to view markdown files on Mac in 2026

Every way to open a .md file on macOS — Finder, Quick Look, Marked, Typora, MDHero — compared.

 Comparison

Quick Look vs MDHero for markdown

When the built-in macOS Quick Look is enough, and when a dedicated markdown viewer for Mac wins.

 Roundup

Best free markdown viewers in 2026

The shortlist of free markdown apps for Mac, Windows, and beyond — with honest pros and cons.

Cross-platform user? See the Windows markdown viewer page, or browse all MDHero articles.

Free, open source, and built for your Mac.

Download MDHero and start viewing markdown files in seconds.

Download for macOS

Also available for Windows.