Markdown Previewer

About

A Chrome (and Chromium derivatives) extension that renders local `.md` files beautifully — right in the browser.

Open any markdown file via `file://` protocol and get GitHub-style rendering with a navigable outline, Mermaid diagrams, syntax highlighting, interactive checkboxes, and dark mode.

MARKDOWN RENDER ENGINE
Full GitHub Flavored Markdown support powered by markdown-it, plus:

- Syntax-highlighted code blocks - 20+ languages with automatic detection, language labels, and one-click copy
- Mermaid diagrams - flowcharts, sequence diagrams, Gantt charts, and more rendered inline as SVG
- Math / LaTeX - KaTeX rendering for inline and block equations
- Task lists - interactive checkboxes you can toggle and save (see below)
- Tables - full GFM tables with colspan, rowspan, and multi-line cell support
- Footnotes - numbered references with back-links
- GitHub-style alerts - `[!NOTE]`, `[!TIP]`, `[!IMPORTANT]`, `[!WARNING]`, `[!CAUTION]`
- Emoji shortcodes - `:rocket:` becomes :rocket:
- Subscript / Superscript - `H~2~O` and `x^2^`
- Highlighted text - `==marked==`
- Definition lists - term/definition pairs

INTERACTIVE CHECKBOXES
Click a checkbox in the rendered preview to toggle it. A floating save bar appears so you can download the updated file with your changes preserved. No editor needed.

SIDEBAR OUTLINE
A collapsible sidebar shows the full heading hierarchy of the document:

- Hierarchical tree with collapsible sections
- Fuzzy search to filter headings instantly
- Scroll spy highlights the current section as you read
- Keyboard navigation through search results

HOW IT WORKS
The extension injects a content script into `file://` URLs matching `.md` and `.markdown` extensions. It reads the raw text content, parses it through markdown-it with all configured plugins, and replaces the page with the rendered output — styled, themed, and ready to read.

Settings and preferences are stored in `chrome.storage.sync`, so they follow you across devices where you're signed into Chrome.

PERMISSIONS
- Storage - persist theme, plugin settings, and UI preferences
- Downloads - save modified files when checkboxes are toggled

BUILT WITH
- WXT (https://wxt.dev/) — Vite-based browser extension framework
- markdown-it (https://github.com/markdown-it/markdown-it) — Markdown parser
- highlight.js (https://highlightjs.org/) — Syntax highlighting
- Mermaid (https://mermaid.js.org/) — Diagram rendering
- KaTeX (https://katex.org/) — Math typesetting