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Baivab Sarkar edited this page Apr 29, 2026 · 1 revision

FAQ

Frequently asked questions about Markdown Viewer.

General

What is Markdown Viewer?

Markdown Viewer is a free, open-source, GitHub-style Markdown editor and live-preview application that runs entirely in the browser. It lets you write Markdown and see the rendered output side by side in real-time, with support for syntax highlighting, LaTeX math, Mermaid diagrams, and more.

Is it free to use?

Yes. Markdown Viewer is completely free and open-source under the Apache 2.0 License.

Do I need to create an account?

No. The application requires no sign-up, registration, or login.

Does Markdown Viewer send my content to a server?

No. All processing is done entirely in your browser. No text you type is ever transmitted to any server. Your content stays on your device.

Do you collect analytics or telemetry?

No. The application does not include analytics scripts, advertising pixels, or tracking beacons.

What data is stored locally?

Markdown Viewer stores editor content, tab state, and preferences (theme, view mode, sync scroll) in your browser’s localStorage for autosave and restore.

How do I clear my local data?

Use your browser’s Site Data or Clear Storage controls for the site. This removes autosaved content and preferences.

What external network requests are made?

By default, the app loads libraries from public CDNs (cdnjs, jsDelivr). GitHub Import uses api.github.com and raw.githubusercontent.com to fetch public files. Self-host the libraries and avoid GitHub import to eliminate these requests.

Which browsers are supported?

Markdown Viewer works in all modern browsers:

  • Chrome / Chromium 90+
  • Firefox 90+
  • Edge 90+
  • Safari 15+

Features

Does it support GitHub Flavored Markdown (GFM)?

Yes. Markdown Viewer implements the full GitHub Flavored Markdown specification, including tables, task lists, strikethrough, and autolinks.

Can I render mathematical equations?

Yes. Markdown Viewer supports LaTeX math via MathJax:

  • Inline math: $E = mc^2$
  • Block/display math: $$\int_0^\infty e^{-x} dx = 1$$

See the Markdown Reference — Math section for more examples.

Can I render diagrams?

Yes. Markdown Viewer supports Mermaid diagrams using fenced code blocks with the mermaid language identifier. Supported diagram types include flowcharts, sequence diagrams, Gantt charts, class diagrams, entity-relationship diagrams, and more.

See the Features — Mermaid Diagrams section for details.

Can I export to PDF?

Yes. Click the Export → PDF button in the toolbar. The PDF is generated client-side using jsPDF and html2canvas.

For higher-quality PDF output (especially for wide code blocks or complex diagrams), use your browser's built-in Print → Save as PDF function (Ctrl+P / Cmd+P).

Does the editor auto-save my content?

Yes. The editor content is automatically saved to the browser's localStorage after each change. Your content is restored the next time you open the application in the same browser.

Can I share my document with someone?

Yes. Click the Share button in the toolbar. Your content is compressed and encoded into the URL. Share the resulting URL — when the recipient opens it, the editor is pre-populated with your content.

Note: Very large documents produce very long URLs, which may not work in all contexts.

Installation & Deployment

How do I run Markdown Viewer locally?

The quickest options are:

# With Docker:
docker run -p 8080:80 ghcr.io/thisis-developer/markdown-viewer:latest

# With Python:
git clone https://github.com/ThisIs-Developer/Markdown-Viewer.git
cd Markdown-Viewer
python3 -m http.server 8080

See the Installation page for all options.

Can I run it without Docker?

Yes. The web app is pure HTML/CSS/JavaScript with no build step. Clone the repository and serve the root directory with any static web server (Python, Node.js serve, VS Code Live Server, Apache, Nginx, etc.).

Can I use it offline?

  • Web app: The application loads libraries from CDNs, so you need an internet connection for the initial load. Once assets are cached, it works offline until the cache is cleared.
  • Desktop app: The desktop application uses the same CDN libraries by default. It can run offline after caching or if you replace CDN links with local copies and rebuild.
  • Self-hosted Docker: Bundling CDN libraries locally makes the web app fully offline. By default, the Docker image still loads CDN libraries.

Is there a desktop version?

Yes. A native cross-platform desktop app is available for Windows, Linux, and macOS, built with Neutralinojs. Download the binary for your platform from the Releases page.

See the Desktop App wiki page for build instructions.

Troubleshooting

The preview is not updating in real-time.

  1. Make sure JavaScript is enabled in your browser.
  2. Try a hard refresh (Ctrl+Shift+R / Cmd+Shift+R).
  3. Check the browser console (F12 → Console) for errors and report them as a GitHub Issue.

Math equations are not rendering.

MathJax loads from a CDN. Ensure you have an active internet connection. If MathJax has already loaded but equations still don't render, check that your LaTeX syntax is correct — see Markdown Reference — Math.

Mermaid diagrams are not rendering.

Check that:

  1. The code block is tagged with mermaid (lowercase).
  2. Your diagram syntax is valid. You can validate it at mermaid.live.
  3. There are no JavaScript errors in the browser console.

The PDF export looks different from the preview.

This is a known limitation of the html2canvas approach. For better-quality PDF output, use Print → Save as PDF in your browser (Ctrl+P / Cmd+P).

The desktop app binary won't open on macOS.

macOS blocks unsigned binaries. Run this command to remove the quarantine flag:

xattr -d com.apple.quarantine markdown-viewer-mac_universal
chmod +x markdown-viewer-mac_universal
./markdown-viewer-mac_universal

Alternatively, right-click the file in Finder, select Open, and confirm the prompt.

The desktop app binary won't open on Linux.

Make sure the binary is executable:

chmod +x markdown-viewer-linux_x64
./markdown-viewer-linux_x64

Contributing

How can I contribute?

See the Contributing page for the full guide. In summary:

  1. Fork the repository.
  2. Create a feature branch (git checkout -b feature/my-feature).
  3. Make and test your changes.
  4. Open a Pull Request against main.

Where do I report bugs or request features?

Open a GitHub Issue with a clear description and (for bugs) steps to reproduce.

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