Create Markdown Documents in C#

Creating Markdown programmatically is useful when building report generators, documentation automation tools, and static site generators. Aspose.HTML for .NET allows you to construct Markdown documents using a syntax tree (AST) and serialize them back to .md files.

In this article, you will learn how to:

• Create a Markdown document from scratch.
• Add headings and paragraphs.
• Insert structured content.
• Save Markdown to a file.

How Markdown Generation Works in Aspose.HTML

Markdown documents are built using:

• MarkdownSyntaxTree – represents the Markdown document.
• MarkdownSyntaxFactory – creates syntax nodes.
• AppendChild() – adds nodes to the document.
• Save() – serializes the tree back to .md.

This AST-based approach makes it possible to create complex Markdown documents in .NET applications without manual text manipulation. Instead of writing plain text, you construct a document structurally.

Creating Structured Markdown Content

When generating Markdown programmatically in .NET, each structural element – heading, paragraph, list, block quote, or code block – should be created as an explicit syntax node. This ensures valid Markdown structure, correct block separation, consistent formatting, and easier document maintenance.

The following example demonstrates how to generate a structured Markdown document. It generates a properly formatted document with multiple sections and clean spacing.

Example 1 – Create a Markdown File in C#

// Create Markdown document
var md = new MarkdownSyntaxTree(new Configuration());
var factory = md.SyntaxFactory;

// Create H1
var h1 = factory.AtxHeading("Markdown Generation in C#", 1);
h1.GetTrailingTrivia().Add(factory.NewLineTrivia());
md.AppendChild(h1);

// Create introduction paragraph
var intro = factory.Paragraph();
intro.AppendChild(factory.Text(
    "This document was generated programmatically using Aspose.HTML for .NET."));
intro.AppendChild(factory.NewLineTrivia());
intro.AppendChild(factory.Text(
    "The API allows you to build Markdown documents using a structured syntax tree."));
md.AppendChild(intro);

// Add empty line between sections
md.AppendChild(factory.NewLineTrivia());

// Create H2
var h2 = factory.AtxHeading("Why Use AST-Based Generation?", 2);
h2.GetTrailingTrivia().Add(factory.NewLineTrivia());
md.AppendChild(h2);

// Create another paragraph
var paragraph = factory.Paragraph();
paragraph.AppendChild(factory.Text(
    "Using a syntax tree ensures structural correctness and avoids manual string concatenation."));
md.AppendChild(paragraph);

// Save file
var path = Path.Combine(OutputDir, "generated-document.md");
md.Save(path);

This example demonstrates:

• Initializing a MarkdownSyntaxTree with default Configuration.
• Creating ATX-style headings (#, ##) using AtxHeading(text, level).
• Adding multi-sentence paragraphs with Paragraph() and Text().
• Inserting explicit line breaks via GetTrailingTrivia().Add(NewLineTrivia()) for proper block separation.
• Serializing the complete syntax tree to a .md file with Save().

Use case: Generating static documentation pages with fixed content structure.

Example 2 – Generate Sections in a Loop

The following example demonstrates how multiple Markdown sections (for example, H2 headings with paragraphs) are created using a standard for or foreach iteration in C#.

Inside each iteration:

• A heading node is created using AtxHeading().
• A paragraph node is created.
• Text content is appended.
• Both nodes are added to the Markdown syntax tree.

This approach enables scalable Markdown generation in .NET without duplicating code for each section.

var md = new MarkdownSyntaxTree(new Configuration());
var factory = md.SyntaxFactory;

string[] sections = { "Installation", "Configuration", "Usage" };

foreach (var section in sections)
{
    var heading = factory.AtxHeading(section, 2);
    heading.GetTrailingTrivia().Add(factory.NewLineTrivia());
    md.AppendChild(heading);

    var paragraph = factory.Paragraph();
    paragraph.AppendChild(factory.Text(
        $"This section describes how to handle {section.ToLower()} in your application."));
    md.AppendChild(paragraph);

    md.AppendChild(factory.NewLineTrivia());
}

md.Save(Path.Combine(OutputDir, "loop-generated.md"));

What Happens in the Syntax Tree

Each iteration appends new nodes to the MarkdownSyntaxTree:

• AtxHeadingSyntaxNode
• ParagraphSyntaxNode

The order of AppendChild() calls defines the final Markdown layout. Correct placement of line breaks ensures proper block separation in the output file. As a result, the generated .md document contains multiple structured sections created dynamically from runtime data.

This example demonstrates:

• Dynamically building multiple document sections from a string array.
• Reusing syntax factory methods inside a foreach iteration to avoid code duplication.
• Programmatically setting heading levels and paragraph content based on runtime data.
• Maintaining consistent spacing between generated blocks with NewLineTrivia().
• Scaling Markdown generation for data-driven content (e.g., API docs, release notes).

This pattern is useful for:

• Documentation generators
• Automated README creation
• Report builders

Example 3 – Create an Unordered List

Lists are frequently used in README files, technical documentation, and structured content generation. In Aspose.HTML for .NET, unordered list items are created using UnorderedListItem() with a marker parameter.

// Create a new Markdown document with default configuration
MarkdownSyntaxTree markdownDocument = new MarkdownSyntaxTree(new Configuration());
// Get the syntax factory for creating Markdown nodes
MarkdownSyntaxFactory syntaxFactory = markdownDocument.SyntaxFactory;

// Create an H2 heading: "## Key Features"
AtxHeadingSyntaxNode heading = syntaxFactory.AtxHeading("Key Features", 2);
// Add a newline after the heading for proper formatting
heading.GetTrailingTrivia().Add(syntaxFactory.NewLineTrivia());
markdownDocument.AppendChild(heading);

// Create an unordered (bulleted) list
UnorderedListSyntaxNode unorderedList = syntaxFactory.UnorderedList();

// Define the list items content
string[] features = { "Parse Markdown documents", "Modify document structure", "Create Markdown dynamically" };

// Add each feature as a list item
foreach (string featureText in features)
{
    // Create a list item with "-" marker
    ListItemSyntaxNode listItem = syntaxFactory.UnorderedListItem("-");
    // Create a paragraph and add the feature text
    ParagraphSyntaxNode paragraph = syntaxFactory.Paragraph();
    paragraph.AppendChild(syntaxFactory.Text(featureText));
    // Assemble: paragraph → list item → list
    listItem.AppendChild(paragraph);
    unorderedList.AppendChild(listItem);
}

// Add the completed list to the document
markdownDocument.AppendChild(unorderedList);

// Save the Markdown file to disk
markdownDocument.Save(Path.Combine(OutputDir, "unordered-list.md"));

This method ensures that Markdown lists are created in a structurally valid way using the syntax tree rather than manual string formatting.

This example demonstrates:

• Constructing bulleted lists using UnorderedList() and UnorderedListItem("-").
• Nesting Paragraph nodes inside list items for valid Markdown list syntax.
• Iterating over a collection to populate list content without manual string formatting.
• Assembling complex structures: heading → list container → list items → paragraphs → text.
• Ensuring structural validity by building lists through the syntax tree.

Use case: Generating feature lists, changelogs, or step-by-step instructions in README files.

Common Mistakes and Fixes

Mistake	Symptom	Fix
Missing line breaks between blocks	Headings and paragraphs merge on the same line	Add NewLineTrivia() after headings
Chaining AppendChild() calls	Compilation error: cannot convert from ‘void’ to ‘MarkdownSyntaxNode’	Store nodes in variables first
Creating list items without paragraphs	Invalid Markdown structure or missing content	Wrap text in Paragraph before adding to list item
Replacing text via ToString()	Changes don’t persist in saved file	Work with the syntax tree directly
Assuming FirstChild is always text	Text replacement fails or targets wrong node	Traverse children to find TextSyntaxNode

Quick Recipes

Setup (required for all examples):

var md = new MarkdownSyntaxTree(new Configuration());
var mdf = md.SyntaxFactory;

Create an H3 Heading

var heading = mdf.AtxHeading("Subsection", 3);
heading.GetTrailingTrivia().Add(mdf.NewLineTrivia());
md.AppendChild(heading);

Add a Simple Paragraph

var paragraph = mdf.Paragraph();
paragraph.AppendChild(mdf.Text("Generated paragraph content."));
md.AppendChild(paragraph);

Add Bold Text (strong)

var bold = mdf.Emphasis(Emphasis.Strong);
bold.AppendChild(mdf.Text("Important text"));
md.AppendChild(bold);

Add Italic Text (emphasis)

var italic = mdf.Emphasis(Emphasis.Emphasis);
italic.AppendChild(mdf.Text("Emphasized text"));
md.AppendChild(italic);

Add a Link

var link = mdf.InlineLink("Link text", "https://example.com", "Optional title");
md.AppendChild(link);

Add an Image

string altText = "Aspose.HTML logo";
string label = "Aspose.HTML";
string href = "https://products.aspose.com/html/images/headers/aspose_html.svg";

var image = mdf.InlineImage(altText, href, label);
md.AppendChild(image);

Related Articles

• Markdown Syntax – Basic Tutorial – Overview of Markdown elements and syntax rules.
• Markdown Converter – C# – Convert Markdown to HTML and other formats using Aspose.HTML for .NET.
• Parse and Process Markdown in C# – Build a syntax tree (AST), traverse nodes, extract headings and tables programmatically.
• Edit Markdown Files in C# – Change headings, update paragraphs, remove list items, and manipulate the Markdown AST.