HtmlToOpenXml 4.0.0

What is HtmlToOpenXml?

HtmlToOpenXml is a mature, high-fidelity converter that translates complex HTML structures into native OpenXML elements, ensuring your content renders exactly as intended across all Microsoft Word users.

Originally created in 2009 to transform user-generated content into templated Word documents, it has evolved into a mature HTML-to-OpenXML converter supporting styles, numbering, images, bookmarks, page layout, tables, document template, and custom resource resolution.

Supports .Net Framework 4.6.2, .NET Standard 2.0, .NET 8 .NET 10 which are all LTS.

Built on top of DocumentFormat.OpenXml and AngleSharp.

→ Official Nuget Package (❗ Update your bookmark, suffix .dll removed)

Quick Start

When creating a blank document:

await using var generatedDocument = new MemoryStream();
using var package = WordprocessingDocument.Create(generatedDocument, WordprocessingDocumentType.Document);

var mainPart = package.AddMainDocumentPart();
new Document(new Body()).Save(mainPart);
HtmlConverter converter = new(mainPart);
await converter.ParseBody(html);

When inserting inside an existing document:

await using var generatedDocument = new MemoryStream();
await templateFileStream.CopyToAsync(generatedDocument);
using var package = WordprocessingDocument.Open(generatedDocument, true);
MainDocumentPart? mainPart = package.MainDocumentPart;
if (mainPart == null)
{
    mainPart = package.AddMainDocumentPart();
    new Document(new Body()).Save(mainPart);
}
HtmlConverter converter = new(mainPart);
await converter.ParseBody(html);

Documentation

Documentation covers from the minimal code to advanced scenarios.

Guides & Tutorials

• Getting Started Guide
• LLM Guidance

API Reference

• API Contract

Technical Deep Dive

• Numbering List
• Advanced Table Structures (Row/ColSpan, ColGroup)
• Image Processing
• Performance notes and memory allocations

How to implement or debug features

My reference bibles cover both OpenXml and HTML:

• MDN
• W3Schools
• OpenXml MSDN

Open MS Word or Apple Pages and design your expected output. Save as a DOCX file, then rename as a ZIP. Extract the content and inspect those files: document.xml, numbering.xml (for list) and styles.xml.

Acknowledgements

Thank you to all contributors that share their bug fixes (in no particular order): scwebgroup, ddforge, daviderapicavoli, worstenbrood, jodybullen, BenBurns, OleK, scarhand, imagremlin, antgraf, mdeclercq, pauldbentley, xjpmauricio, jairoXXX, giorand, bostjanKlemenc, AaronLS, taishmanov, AyUsH18102001. And thanks to David Podhola for the Nuget package.

Logo provided with the permission of Enhanced Labs Design Studio.

Support

This project is open source and I do my best to support it in my spare time. I'm always happy to receive Pull Request and grateful for the time you have taken. Please target branch dev only. If you have questions, don't hesitate to get in touch with me!