MDHero

Write anywhere, read here. A beautiful, native Markdown viewer for macOS and Windows. ~11MB. Free. Open source.

Open local .md files, paste AI-generated markdown, or fetch from any public URL — and read it the way it was meant to be read.

Why MDHero

Markdown is where developers, writers, and AI live today — READMEs, Claude Code plans, LLM chat exports, notes, documentation. But opening a .md file in a code editor gives you ugly monospace text. Opening a web-based viewer means uploading your files. GitHub renders it beautifully but only if the file is in a repo.

MDHero is a native viewer for everything in between. Your files stay local. Rendering is instant. Works offline. Looks like it belongs on your machine.

Features

Reading

• Beautiful rendering — Apple-inspired typography, light & dark themes
• Syntax highlighting — 25+ languages via highlight.js
• Math & diagrams — KaTeX for equations, Mermaid for flowcharts
• Reader controls — adjust font, size, line height, width
• Zen mode — distraction-free full-screen reading
• Print/Export to PDF — with clean print styles

Navigation

• Multiple tabs — open many files, drag to reorder, Cmd+1–9 to switch
• Table of Contents — auto-generated sidebar with active heading tracking
• Search (Cmd+F) — with match highlighting
• Vim keys — j/k/gg/G/d/u/[/] for keyboard-first navigation
• Image lightbox — click to zoom, arrow keys for next/prev

Opening Files

• Local files — drag-drop, Cmd+O, "Open With" from Finder
• Pinned folders — quick access to markdown in your favorite directories
• Claude Code Plans — auto-discovers ~/.claude/plans/
• Open URL — fetch from GitHub, Gist, GitLab, Bitbucket, or any public URL
• Paste mode (Cmd+Shift+V) — render LLM output instantly, auto-unescapes \n
• Recent files — pick up where you left off, with reading progress per file

Live

• File watching — edit in VS Code, see updates instantly in MDHero
• Auto-reload — survives atomic saves (VS Code, vim, etc.)

Sharing

• Copy as Rich Text — paste directly into Google Docs, Notion
• Copy as Markdown — raw source
• Export PDF — print-friendly output

Install

macOS: Download .dmg from Releases →

Windows: Download .msi from Releases →

Or build from source (see below).

Keyboard Shortcuts

Cmd → Ctrl on Windows/Linux.

Development

pnpm install
pnpm tauri dev          # Run dev with hot reload
pnpm tauri build        # Production build (outputs DMG/MSI)
pnpm check              # TypeScript check

Requirements: Node 22+, Rust stable, pnpm 10+.

Port 1420 is used for dev. Kill stale processes with lsof -ti:1420 | xargs kill -9.

Stack

• Tauri v2 — Rust backend, ~11MB binary
• SvelteKit — frontend with Svelte 5 runes
• markdown-it — rendering pipeline
• highlight.js — syntax highlighting
• KaTeX — math rendering
• Mermaid — diagram rendering
• Tailwind CSS v4 — styling

Privacy

MDHero runs entirely on your machine.

• No telemetry. No analytics. No tracking.
• No account required. Use it anonymously.
• Your files never leave your computer. Rendering happens locally.
• Network access is limited to: checking for new releases (once per 24h) and fetching URLs you explicitly paste into the Open URL feature.

Roadmap

Coming next:

• Quick Switcher (Cmd+P fuzzy finder)
• Folder watch (auto-refresh pinned folder contents)
• Export to self-contained HTML
• Presentation mode
• Compare / diff view

Contributing

See CONTRIBUTING.md for setup, guidelines, and how to propose changes.

License

MIT © Vaibhav Kakde