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

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 app for everything in between. Your files stay local. Rendering is instant. Edit in place when you need to. 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

Editing (v0.2.0)

• Lightweight in-app editor — Cmd+E flips any local file into edit mode
• Save with Cmd+S — writes back to disk; the file watcher knows it was you and skips the reload
• Stays where you were — source-line scroll sync keeps your position across viewer ↔ raw ↔ edit
• Dirty indicator — • in the tab title and toolbar when you have unsaved changes
• Per-tab edit state — switch tabs and back; your edits are right where you left them

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

Screenshots

Syntax Highlighting

25+ languages with automatic detection, copy button, and clean typography.

Math Rendering (KaTeX)

Render LaTeX equations instantly — from inline math to full block equations and matrices.

Mermaid Diagrams

Flowcharts, sequence diagrams, class diagrams, and more — rendered natively.

Zen Mode

Distraction-free full-screen reading. Just you and the document.

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