Converting HTML content to PDF is essential for sharing, printing, archiving, or preserving formatting. With the GroupDocs.Conversion Cloud SDK for .NET, you can perform high-fidelity HTML to PDF conversions without relying on browser plugins or external tools.

In this article, you’ll learn how to:

HTML to PDF Conversion API

The GroupDocs.Conversion Cloud SDK for .NET is a high-quality, scalable REST API offering the capabilities to perform HTML to PDF conversion online. It ensures that the formatting of content including design, layout, and embedded media is maintained in the resultant PDF.

Prerequisites

  • A .NET development environment (e.g., Visual Studio)
  • GroupDocs.Conversion Cloud SDK for .NET installed via NuGet
  • Client ID and Client Secret from GroupDocs Cloud

Install the SDK using NuGet:

Install using npm:

PM> NuGet\Install-Package GroupDocs.Conversion-Cloud

Step-by-Step: Convert HTML to PDF in C#

Please follow the steps given below to perform free online HTML to PDF conversion using C# .NET:

📌 Step 1: Initialize API Configuration:

var config = new Configuration
{
    ClientId = "YOUR_CLIENT_ID",
    ClientSecret = "YOUR_CLIENT_SECRET"
};

var convertApi = new ConvertApi(config);
var fileApi = new FileApi(config);

📌 Step 2: Upload HTML File to Cloud Storage:

using (var fileStream = File.OpenRead("input.html"))
{
    var uploadRequest = new UploadFileRequest("input.html", fileStream);
    fileApi.UploadFile(uploadRequest);
}

📌 Step 3: Define Conversion Settings and Convert:

var settings = new ConvertSettings
{
    FilePath = "input.html",
    Format = "pdf",
    OutputPath = "converted/output.pdf"
};

var request = new ConvertDocumentRequest(settings);
convertApi.ConvertDocument(request);
Console.WriteLine("✅ HTML file successfully converted to PDF.");
free html to pdf converter

Image:- A preview of HTML to PDF conversion.

Download the sample PDF file generated in the above example from resultant.pdf.

Optional: Convert HTML to PDF with cURL

If you prefer using command-line tools or automation pipelines, the GroupDocs.Conversion Cloud can also be accessed via cURL.

  • This method is ideal for automation pipelines and script-based conversions.

Step 1: Get JWT Access Token

curl -v "https://api.groupdocs.cloud/connect/token" \
-X POST \
-d "grant_type=client_credentials&client_id=YOUR_CLIENT_ID&client_secret=YOUR_CLIENT_SECRET" \
-H "Content-Type: application/x-www-form-urlencoded"

Step 2: Convert HTML to PDF

curl -v "https://api.groupdocs.cloud/v2.0/conversion" \
-X POST \
-H "accept: application/json" \
-H "authorization: Bearer {accessToken}" \
-H "Content-Type: application/json" \
-d "{  \"StorageName\": \"default\",  \"FilePath\": \"{sourcePDF}\",  \"Format\": \"html\",  \"OutputPath\": \"{finalOutput}\"}"

Replace:

  • sourceFile, resultantFile, and accessToken with actual values.
  • Now in order to save the PDF on local drive, you may consider using the following cURL command:
curl -v "https://api.groupdocs.cloud/v2.0/conversion" \
-X POST \
-H "accept: application/json" \
-H "authorization: Bearer {accessToken}" \
-H "Content-Type: application/json" \
-d "{  \"StorageName\": \"default\",  \"FilePath\": \"{sourceFile}\",  \"Format\": \"html\"}" \
-o "myOutput.html"

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Conclusion

With the help of GroupDocs.Conversion Cloud SDK for .NET, you can seamlessly convert HTML to PDF within your C# applications. Whether it’s for document export, report generation, or archiving styled web content, this API offers full flexibility and control.

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