MarkCraft
A free, open-source Markdown viewer, editor and reviewer for Chrome. Open any .md file — local or remote — and get a polished reading view with diagrams, math, outline, annotations, live reload, WYSIWYG editing, presentation mode, mind maps and Word/HTML/PDF export. Everything runs locally; nothing is collected.
Website · 简体中文说明 · Issues
Features
Reading
- Takes over raw
.md / .markdown / .mdx / … files on file:// and http(s) (e.g. raw.githubusercontent.com); .txt optional
- GitHub Flavored Markdown, highlight.js (12 syntax themes), KaTeX, footnotes, GitHub alerts, front-matter metadata card
- Diagrams: Mermaid, Graphviz, WaveDrom (local), PlantUML (opt-in server with explicit consent) — fullscreen zoom/pan and SVG/PNG/JPEG download
- Plugins: emoji,
==mark==, ++ins++, ~sub~, ^sup^, definition lists, abbreviations, ::: containers, typographer, advanced tables, Mintlify components (Card, Tabs, Steps, Accordion, CodeGroup, callouts…)
- Outline with scroll-spy, search, expand/collapse; find in page (case / word / regex); image lightbox; reading progress, word count, sticky table headers, RTL auto-direction; light/dark/sepia themes, centered or full-width layout
Files
- Folder browser with sort, group, filter, bookmarks and full-text search in folder
- Live auto-refresh with a +/− diff banner (accept / dismiss) when files change on disk
- Drag & drop, recent documents in the popup
Editing
- Read / WYSIWYG (Milkdown) / Source modes, Markdown paste, save (⌘S) back to the file
- Saves straight back to the file with Chrome's File System Access API: files opened from a folder or the file picker save directly; a local
file:// page asks once for the file and remembers it
Review & AI
- Highlight (4 colors), underline and comment; annotations persist and appear in print and exports
- Hand off review comments as a prompt, or ask the built-in agent to edit the document and review the diff before applying
- The built-in agent uses the AI provider you configure in Settings → AI Provider (OpenAI-compatible or Anthropic API format, your own API key, stored only on this device); it is unavailable until one is set up
Present & export
- Presentation mode (themes, colors, background image, speaker notes, auto-play, touch)
- Interactive mind map (SVG/PNG/JPEG)
- Export to Word (.docx), HTML, print/PDF; copy as rich text
Settings — General, Appearance, Plugins, Presentation, PlantUML, customizable Shortcuts, Import/Export. Interface in English and 简体中文.
Install (from source)
git clone https://github.com/zhangweiii/markcraft.git
cd markcraft
npm install
npm run build # outputs dist/
- Open
chrome://extensions, enable Developer mode, click Load unpacked and pick dist/.
- In MarkCraft's Details, enable Allow access to file URLs for local files.
npm run package builds markcraft.zip for the Chrome Web Store and refuses to package private keys, source maps or local config files.
Development
npm run watch # incremental build
npx playwright install chromium # once
npm test # end-to-end tests (Playwright, test/fixtures)
| Path | What |
|---|
src/detect.js | content script: detects raw Markdown and opens the viewer |
src/viewer/ | the viewer app (rendering, editor, panels, exports, presentation, mind map) |
src/shared/ | settings + schema-driven settings UI, IndexedDB, i18n, icons, design tokens |
src/popup.js, src/options.js | toolbar popup and options page |
scripts/test.mjs | end-to-end test suite |
site/ | website (markcraft.cc), deployed to GitHub Pages; npm run screenshots refreshes its images |
Privacy
No analytics, no telemetry, no accounts. Files never leave your machine. The only optional network features are PlantUML rendering (off until you consent) and loading images/links referenced by your documents.
Credits
Built on marked, highlight.js, KaTeX, Mermaid, Viz.js, WaveDrom, Milkdown, markmap, docx, DOMPurify, jsdiff and Lucide icons.
License
MIT
