In today’s digital landscape, HTML is one of the most widely used formats for displaying and sharing structured data online. However, when it comes to archiving, distribution, or offline access, PDF remains the format of choice. Developers often need to convert HTML to PDF for creating reports, invoices, or preserving web content in a universally compatible format.

This article is covering following topics:

HTML to PDF Conversion SDKs

The GroupDocs.Conversion Cloud SDK for .NET provides a powerful and scalable solution for file format transformation. While using the capabilities of this API, you can seamlessly convert HTML to PDF, ensuring accuracy, consistency, and superior performance—all without installing additional software.

Getting Started with HTML to PDF Conversion

Before you begin, ensure you have the following prerequisites:

  1. A GroupDocs Cloud account to obtain your Client ID and Client Secret. For more information, please visit short tutorial.
  2. A sample HTML file or webpage for testing.
  3. A configured .NET development environment (such as Visual Studio or Rider).

You can install the SDK from NuGet Package Manager by running the following command:

Install-Package GroupDocs.Conversion-Cloud -Version 25.9.0

Convert HTML to PDF with C#

Let’s explore how to perform HTML to PDF conversion programmatically using C# and the GroupDocs Cloud SDK.

  1. Create an instance of Configuration class where we pass client credentials as arguments.
var configuration = new Configuration
{
    AppSid = "YOUR_CLIENT_ID",
    AppKey = "YOUR_CLIENT_SECRET"
};
  1. Initialize an instance of ConvertApi and FileApi where we pass Configuration object as arguments.
var convertApi = new ConvertApi(configuration);
var fileApi = new FileApi(configuration);
  1. Upload the input HTML to cloud storage.
using (var stream = File.OpenRead("source.html"))
{
    var uploadRequest = new UploadFileRequest("source.html", stream);
    fileApi.UploadFile(uploadRequest);
}
  1. Create an instance of ConvertSettings where we specify the name for input HTML, output format as pdf and resultant PDF name.
var settings = new ConvertSettings
{
    FilePath = "index.html",
    Format = "pdf",
    OutputPath = "converted/html-to-pdf-result.pdf"
};
  1. Call the ConvertDocumentRequest API to convert HTML to PDF format. After successful conversion, the resultant PDF is stored in cloud storage.
var request = new ConvertDocumentRequest(settings);
convertApi.ConvertDocument(request);

Once the request is executed, your HTML file will be converted into a high-quality PDF and stored in the specified output folder within your cloud storage.

HTML to PDF Conversion using cURL

If you prefer to perform conversions through scripting or automation pipelines, cURL is an excellent alternative. It allows you to execute REST API calls directly from the command line, making it ideal for quick testing and batch processing.

Why Use cURL for HTML to PDF Conversion?

  • No SDK installation required.
  • Perfect for shell scripts, CI/CD workflows, or backend services.
  • Lightweight and easy to automate.

Before running the HTML to PDF conversion command, generate your JWT access token, based on client credentials. Once the token has been generated, please execute the following command.

curl -v "https://api.groupdocs.cloud/v2.0/conversion" \
-X POST \
-H "accept: application/json" \
-H "authorization: Bearer {ACCESS_TOKEN}" \
-H "Content-Type: application/json" \
-d "{  \"StorageName\": \"internal\",  \"FilePath\": \"{sourceFile}\",  \"Format\": \"pdf\",  \"LoadOptions\": {    \"Format\": \"html\"  },  \"ConvertOptions\": {    \"FromPage\": 1,    \"PagesCount\": 1,    \"Pages\": [      1    ],    \"WatermarkOptions\": {      \"Text\": \"Confidential\",      \"FontName\": \"Arial\",      \"FontSize\": 12,      \"Bold\": false,      \"Italic\": true,      \"Color\": \"Red\",      \"Width\": 10,      \"Height\": 6,      \"Top\": 100,      \"Left\": 100,      \"RotationAngle\": 10,      \"Transparency\": 0.8,      \"Background\": true,      \"AutoAlign\": true    }  },  \"OutputPath\": \"{converted}\"}"

Replace {ACCESS_TOKEN} with your generated JWT token and index.html with the name of your HTML file.

Try Free HTML to PDF Converter

If you want to explore the conversion process without writing any code, try the free HTML to PDF Converter web app powered by GroupDocs.Conversion Cloud. It lets you upload any HTML file or URL and instantly download the generated PDF.

html to pdf converter

Conclusion

Converting HTML to PDF using .NET REST API provides developers with a reliable way to preserve webpage layouts, styles, and content in a portable format. With GroupDocs.Conversion Cloud SDK for .NET, you can automate this process in just a few lines of code—whether you need to convert single HTML files or entire batches of web pages.

We highly recommend visiting the following links to learn more about:

Frequently Asked Questions (FAQs)

  1. How can I convert HTML to PDF using C# .NET?
  • You can use GroupDocs.Conversion Cloud SDK for .NET to upload an HTML file, configure the output format as PDF, and execute the ConvertDocument() method to generate the converted file.
  1. Does this API support converting HTML with CSS and images?
  • Yes. The SDK maintains all linked resources, ensuring your converted PDF preserves layout, fonts, images, and styling accurately.
  1. Can I convert web pages directly from URLs?
  • Yes. You can specify a webpage URL in the input path, and the API will render the HTML content and convert it into a PDF document.

4. Do I need to install any third-party tools like Adobe Acrobat?

  • No. The entire process is cloud-based—no local installation or additional software is required.