HelpViewer is a lightweight and simple reader for ZIP archives or directories - whether stored locally or on a network - containing Markdown and HTML files. It’s designed as a modern and portable help file viewer that runs directly in your web browser.

It supports offline use without requiring any backend or server, offering a clean and responsive interface inspired by the classic desktop help viewers from the Windows era.

⚖ HelpViewer is MIT licensed.

👉 Open this file in HelpViewer to see it in action.

🌐 Visit our website to learn more.

Interested?

📦 Download the latest HelpViewer release package.

💬 Join our Discord user group.

Don’t want to just read other people’s help files?

📗 Start to write your own help files.

Want to be involved even more?

📘 Read our Contribution guidelines.

📜 Check out other important project policies.

📙 Explore Documentation for developers to start custom development.

• No installation required - just unzip and run locally
• Multiplatform - works on all major operating systems via web browsers
• Ready to work in offline mode without any backend or local server
  • A browser with CORS policies disabled is recommended. Otherwise, functionality is partially limited and you must manually select the data file and help file at startup.
• Responsive (desktop and other devices supported)
• Lightweight - distribution package under 1.38 MiB (💾; most part of solution compressed)
• Supports export of a chapter (in 2 clicks) or the complete help file (in 4 clicks) to HTML, Markdown, LaTeX, or ePub formats.
• Accessibility rules WCAG 2.1 implemented (accessibilitychecker.org: 89 %, Lighthouse: 96%, Web Aim)
• Print friendly version (prefers greyscale)
• Personal notes on chapter paragraphs
• Easily switch between different language versions of the viewer interface and help file
• See the full list

• Single platform for rendering Markdown and HTML content (both can be present in one help ZIP file)
• ZIP compression method supported (one single part file only)
• Rendering diagrams by Mermaid library (included in deployment package)
• See the full list

1. Start your browser with CORS restrictions disabled.
2. In this session you will open index.html file in your browser.
3. Set the URL parameter ?d=X, where X is the path to your ZIP file or you can define path ending with / if you want to read a directory.
   If you skip this step, ./hlp/Help-{current language}.zip will be used by default.

The UI is intuitive and easy to use, but if any questions arise, the User Quick Guide is there to help you.

• JSZip library (under MIT)
• Marked (under MIT)
• Mermaid (under MIT)
• Prism (under MIT)

The solution is implemented using pure JavaScript. Please ensure that JavaScript is enabled in your browser to ensure proper functionality.

Do you see the page with “⚠ Do you see this message only?”? Then the browser is not loading the data from the ZIP help file.
This may be caused by your browser blocking local file access (file://) due to CORS policy restrictions.

You have 2 options on how to proceed:

1. In the data.zip and Help-(language).zip fields, select the necessary files and click Submit.
2. You need to run your browser in mode with bypass CORS policy:

• Chrome:

  Run in CLI:
  chrome.exe --disable-site-isolation-trials --disable-web-security --user-data-dir="C:\temp"

• Edge:

  Run in CLI:
  msedge --disable-web-security --user-data-dir="C:\temp"

• More in Future plans list.

Some parts of this project were developed with assistance from:

• ChatGPT,
• Copilot

, an AI-powered advisor. While AI helped generate suggestions, the final code and design decisions were made by the project author.

Please note that any use of third-party code generated or suggested by AI is subject to the original licenses of that code.