v0.2.8 · now with AI lookup · free forever

MDHero.
The Markdown viewer you can edit in.
Free, open source.

A free, open source markdown viewer and lightweight markdown editor. Native, under 8MB.

MDHero is a free, open-source Markdown viewer and lightweight editor — about 8MB, built with Tauri and Rust, fully offline with no accounts or telemetry. Open any .md file instantly, then press ⌘E to edit and ⌘S to save.

Download for macOS Download for Windows

MIT licensed · Apple notarized · No telemetry · Under 8MB Source on GitHub

Requires macOS 12+ (Apple Silicon) or Windows 10+. macOS is Apple-notarized; on Windows, bypass SmartScreen once on first run.

Setup guides & platform details: Markdown viewer for Mac Markdown viewer for Windows

The native markdown viewer for your daily workflow

Three reasons you'll leave it on your Dock.

Your files stay local

Everything runs on your machine. No uploads, no cloud, no accounts — total privacy. Open a .md file, read it or edit it, offline or on.

Beautiful by default

Apple-inspired typography with dark mode, syntax highlighting for 25+ languages, KaTeX math, and Mermaid diagrams.

Built for the AI era

Paste ChatGPT or Claude output directly — MDHero auto-detects and cleans up LLM formatting. Also reads Claude Code plans.

Quick answers

Three questions, before you decide.

Is MDHero really free?

Yes — free forever, MIT-licensed, ~8MB, runs entirely offline. No paid tier, no account, no upgrade nag. Source on GitHub.

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What data does MDHero send back?

One update check per 24h with your current version and OS family (darwin or win32). No device IDs, no IPs, no file contents, no telemetry — endpoint source is public.

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How does it compare to Typora, Obsidian, or VS Code?

MDHero is ~8MB versus Typora ~90MB, Obsidian ~180MB, and VS Code ~300MB — built with Tauri and Rust, not Electron. Typora is $14.99 and closed source; MDHero is free and MIT open source.

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See all FAQs

Features

Everything a markdown file needs. Nothing it doesn't.

Small ideas that make a difference every time you open a markdown file — viewing or editing.

01 — Sources

Open anything.

Local files, GitHub URLs, pasted markdown, or Claude Code plans — one app reads them all.

Local files GitHub URLs Paste ~/.claude/plans

Quick actions

Browse files

Open URL

Pin folder

Pinned folders

~/Documents/notes

meeting-2026-04-18.md

product-brief.md

weekly-review.md

~/Code/mdhero/docs

~/.claude/plans

02 — Editor

View, Split, or Edit — one switch.

A real markdown editor built into the viewer. Move between View, Split, and Edit from a single control — Split puts the editor and a live preview side by side. Line numbers in the gutter, ⌘F find that works in every mode, and scroll position that follows you line by line. ⌘S saves, and MDHero warns before you discard unsaved changes.

Split view Line numbers Cmd+S Scroll sync

ViewSplitEdit

notes.md · saved ⌘S

12345678

# Release plan

## v0.2.8

- View / Split / Edit switcher

- Line numbers in the gutter

- Marp presentation mode

03 — Navigation

Tabs, TOC, and your muscle memory.

Multiple tabs with drag-to-reorder. Table of Contents sidebar. Search with ⌘F. Vim keybindings when you want them.

Drag-to-reorder TOC sidebar Vim keys

brief.md

notes.md

api.md

readme.md

Owner: Vaibhav · Status: Draft

A one-page overview of what we're building and why it matters to the people using it every day.

Three outcomes, each measurable within a quarter.

04 — Code

Syntax highlighting that reads like a book.

25+ languages with beautiful code blocks. Copy button on hover. Dark and light themes that agree on what a string should look like.

25+ languages Copy on hover Dark & light themes

 typescript // Count tokens in a markdown document import { tokenize } from './lexer';
export async function countTokens(path: string) { const text = await fs.readFile(path, 'utf8');
const tokens = tokenize(text);
return tokens.filter(t => t.type !== 'whitespace').length;
} 

 python def render(path: str) -> str:
with open(path) as f:
        doc = f.read()
return markdown.to_html(doc, extensions=['tables', 'fenced_code'])

05 — Math & diagrams

Equations and flowcharts, rendered inline.

KaTeX renders LaTeX equations. Mermaid renders flowcharts, sequence diagrams, and more — with no plugins, no extra steps.

KaTeX Mermaid

e^iπ + 1 = 0 · P(A|B) = P(B|A) · P(A)P(B)

06 — LLM paste mode

Paste raw LLM output. Read real markdown.

MDHero auto-detects escaped \n characters and stray backslashes in LLM output and renders clean markdown — no manual cleanup.

ChatGPT Claude Auto-unescape

Paste markdownesc to close

Paste

Open URL

# Plan\n\n1. Parse tokens\n2. **Render** tree\n\n```ts\nconst x = 1;\n```

LLM mode — unescape \n

07 — AI Lookup

Right-click anything. Ask the model.

Select a word or paragraph and right-click — send it to ChatGPT, Claude, Perplexity, Google, or Wikipedia in one click. URL-based, no API keys, no telemetry. Each provider holds your own saved prompts ("Explain this clearly:", "Summarize:") for reuse, configurable in Settings.

ChatGPT Claude Perplexity Google Wikipedia No API keys

Markdown viewers vary widely in how they handle tokenization for syntax highlighting, which affects rendering speed on large files.

08 — Pins

Pin your folders. Open with one click.

Pin frequently-used directories for instant access to every markdown file inside — no more hunting through Finder.

Folder pins Recent files

Pinned folders

~/Desktop/work

LANDING_PAGE_BRIEF.md

CLAUDE.md

release-notes-0.2.6.md

~/obsidian-vault

~/.claude/plans

Recent files

complete-test.md 2m ago

architecture.md yesterday

roadmap.md 3d ago

09 — Presentations

Turn a markdown file into slides.

Add marp: true to the front matter and MDHero opens the document as a native slideshow — arrow keys, Space, Home and End, with optional page numbers. No Marp CLI, no export step, no browser.

Marp No CLI needed Arrow / Space

Three things we're shipping, and why they matter.

2 / 9

How it compares

MDHero vs Typora, Obsidian, and VS Code.

The short version: ~8MB instead of 90–300MB, free instead of $14.99, and a focused viewer-and-editor instead of a full IDE or knowledge base.

Markdown app	MDHero	Typora	Obsidian	VS Code
Price	Free	$14.99	Free	Free
Open source	Yes (MIT)	No	No	Yes
App size	~8MB	~90MB	~180MB	~300MB
Built with	Tauri + Rust	Native	Electron	Electron
Primary mode	Viewer + editor	Editor	Knowledge base	Code editor
Presentation mode (Marp)	Built in	No	Plugin	Extension
LLM paste mode	Yes	No	No	No
AI Lookup (right-click)	Yes	No	No	No
Mac & Windows	Yes	Yes	Yes	Yes

Sizes are approximate install footprints. Typora is a one-time $14.99 purchase; Obsidian is free for personal use with paid sync/publish add-ons. Full platform breakdowns on the Mac and Windows pages, and an honest 7-app roundup in Best Free Markdown Viewers in 2026.

Keyboard shortcuts

For when your hands don't want to leave the keyboard.

Browse files⌘O

Open Settings⌘,

Toggle edit mode⌘E

Save edits⌘S

Paste markdown⌘⇧V

New tab⌘T

Close tab⌘W

Close tab (quit if last)Esc

Switch tabs⌘1…9

Search⌘F

Raw markdown view⌘U

Zoom in / out / reset⌘=/-/0

Scroll down / upj/k

Top / bottomgg/G

On Windows, ⌘ becomes Ctrl.

Open source, MIT licensed.

A free markdown viewer and lightweight markdown editor — open source under MIT, crafted for people who live in their markdown.

Star on GitHub View source Buy me a coffee

MDHero is free and always will be. If it saved you time, a coffee keeps it maintained.

From the MDHero blog

Built with in open source.

MDHero.The Markdown viewer you can edit in.Free, open source.

Three reasons you'll leave it on your Dock.

Your files stay local

Beautiful by default

Built for the AI era

Three questions, before you decide.

Is MDHero really free?

What data does MDHero send back?

How does it compare to Typora, Obsidian, or VS Code?

Everything a markdown file needs. Nothing it doesn't.

Open anything.

Quick actions

Pinned folders

View, Split, or Edit — one switch.

Tabs, TOC, and your muscle memory.

Syntax highlighting that reads like a book.

Equations and flowcharts, rendered inline.

Paste raw LLM output. Read real markdown.

Right-click anything. Ask the model.

Pin your folders. Open with one click.

Pinned folders

Recent files

Turn a markdown file into slides.

MDHero vs Typora, Obsidian, and VS Code.

For when your hands don't want to leave the keyboard.

Open source, MIT licensed.

From the MDHero blog

MDHero.
The Markdown viewer you can edit in.
Free, open source.