HTML to PDF / .NET Examples

This page contains various examples of using the HTML to PDF API in .NET. The examples are complete and fully functional. Read more about how to convert HTML to PDF in .NET.

Basic examples
Advanced examples
Template rendering examples
ASP.NET Web Forms examples

Basic examples

Webpage to PDF file

using System;
using System.IO;

public class ApiTest
{
    public static void Main()
    {
        try
        {
            // Create an API client instance.
            pdfcrowd.HtmlToPdfClient client =
                new pdfcrowd.HtmlToPdfClient("demo", "ce544b6ea52a5621fb9d55f8b542d14d");

            // Specify the mapping of HTML content width to the PDF page width.
            // To fine-tune the layout, you can specify an exact viewport width, such as '960px'.
            client.setContentViewportWidth("balanced");

            // Run the conversion and save the result to a file.
            client.convertUrlToFile("http://www.example.com", "example.pdf");
        }
        catch(pdfcrowd.Error why)
        {
            System.Console.Error.WriteLine("Pdfcrowd Error: " + why);
            throw;
        }
    }
}

Webpage to in-memory PDF

using System;
using System.IO;

public class ApiTest
{
    public static void Main()
    {
        try
        {
            // Create an API client instance.
            pdfcrowd.HtmlToPdfClient client =
                new pdfcrowd.HtmlToPdfClient("demo", "ce544b6ea52a5621fb9d55f8b542d14d");

            // Run the conversion and store the result in the `pdf` variable.
            byte[] pdf = client.convertUrl("http://www.example.com");

            // at this point the "pdf" variable contains PDF raw data and
            // can be sent in an HTTP response, saved to a file, etc.
        }
        catch(pdfcrowd.Error why)
        {
            System.Console.Error.WriteLine("Pdfcrowd Error: " + why);
            throw;
        }
    }
}

Webpage to PDF stream

using System;
using System.IO;

public class ApiTest
{
    public static void Main()
    {
        try
        {
            // Create an API client instance.
            pdfcrowd.HtmlToPdfClient client =
                new pdfcrowd.HtmlToPdfClient("demo", "ce544b6ea52a5621fb9d55f8b542d14d");

            // Create an output stream for the conversion result
            FileStream outputStream = new FileStream("example.pdf", FileMode.CreateNew);

            // run the conversion and write the result to the output stream.
            client.convertUrlToStream("http://www.example.com", outputStream);

            // Close the output stream.
            outputStream.Close();
        }
        catch(pdfcrowd.Error why)
        {
            System.Console.Error.WriteLine("Pdfcrowd Error: " + why);
            throw;
        }
    }
}

HTML file to PDF file

using System;
using System.IO;

public class ApiTest
{
    public static void Main()
    {
        try
        {
            // Create an API client instance.
            pdfcrowd.HtmlToPdfClient client =
                new pdfcrowd.HtmlToPdfClient("demo", "ce544b6ea52a5621fb9d55f8b542d14d");

            // Specify the mapping of HTML content width to the PDF page width.
            // To fine-tune the layout, you can specify an exact viewport width, such as '960px'.
            client.setContentViewportWidth("balanced");

            // Run the conversion and save the result to a file.
            client.convertFileToFile("/path/to/MyLayout.html", "MyLayout.pdf");
        }
        catch(pdfcrowd.Error why)
        {
            System.Console.Error.WriteLine("Pdfcrowd Error: " + why);
            throw;
        }
    }
}

HTML file to in-memory PDF

using System;
using System.IO;

public class ApiTest
{
    public static void Main()
    {
        try
        {
            // Create an API client instance.
            pdfcrowd.HtmlToPdfClient client =
                new pdfcrowd.HtmlToPdfClient("demo", "ce544b6ea52a5621fb9d55f8b542d14d");

            // Run the conversion and store the result in the `pdf` variable.
            byte[] pdf = client.convertFile("/path/to/MyLayout.html");

            // at this point the "pdf" variable contains PDF raw data and
            // can be sent in an HTTP response, saved to a file, etc.
        }
        catch(pdfcrowd.Error why)
        {
            System.Console.Error.WriteLine("Pdfcrowd Error: " + why);
            throw;
        }
    }
}

HTML file to PDF stream

using System;
using System.IO;

public class ApiTest
{
    public static void Main()
    {
        try
        {
            // Create an API client instance.
            pdfcrowd.HtmlToPdfClient client =
                new pdfcrowd.HtmlToPdfClient("demo", "ce544b6ea52a5621fb9d55f8b542d14d");

            // Create an output stream for the conversion result
            FileStream outputStream = new FileStream("MyLayout.pdf", FileMode.CreateNew);

            // run the conversion and write the result to the output stream.
            client.convertFileToStream("/path/to/MyLayout.html", outputStream);

            // Close the output stream.
            outputStream.Close();
        }
        catch(pdfcrowd.Error why)
        {
            System.Console.Error.WriteLine("Pdfcrowd Error: " + why);
            throw;
        }
    }
}

HTML string to PDF file

using System;
using System.IO;

public class ApiTest
{
    public static void Main()
    {
        try
        {
            // Create an API client instance.
            pdfcrowd.HtmlToPdfClient client =
                new pdfcrowd.HtmlToPdfClient("demo", "ce544b6ea52a5621fb9d55f8b542d14d");

            // Specify the mapping of HTML content width to the PDF page width.
            // To fine-tune the layout, you can specify an exact viewport width, such as '960px'.
            client.setContentViewportWidth("balanced");

            // Run the conversion and save the result to a file.
            client.convertStringToFile("<html><body><h1>Hello World!</h1></body></html>", "HelloWorld.pdf");
        }
        catch(pdfcrowd.Error why)
        {
            System.Console.Error.WriteLine("Pdfcrowd Error: " + why);
            throw;
        }
    }
}

HTML string to in-memory PDF

using System;
using System.IO;

public class ApiTest
{
    public static void Main()
    {
        try
        {
            // Create an API client instance.
            pdfcrowd.HtmlToPdfClient client =
                new pdfcrowd.HtmlToPdfClient("demo", "ce544b6ea52a5621fb9d55f8b542d14d");

            // Run the conversion and store the result in the `pdf` variable.
            byte[] pdf = client.convertString("<html><body><h1>Hello World!</h1></body></html>");

            // at this point the "pdf" variable contains PDF raw data and
            // can be sent in an HTTP response, saved to a file, etc.
        }
        catch(pdfcrowd.Error why)
        {
            System.Console.Error.WriteLine("Pdfcrowd Error: " + why);
            throw;
        }
    }
}

HTML string to PDF stream

using System;
using System.IO;

public class ApiTest
{
    public static void Main()
    {
        try
        {
            // Create an API client instance.
            pdfcrowd.HtmlToPdfClient client =
                new pdfcrowd.HtmlToPdfClient("demo", "ce544b6ea52a5621fb9d55f8b542d14d");

            // Create an output stream for the conversion result
            FileStream outputStream = new FileStream("HelloWorld.pdf", FileMode.CreateNew);

            // run the conversion and write the result to the output stream.
            client.convertStringToStream("<html><body><h1>Hello World!</h1></body></html>", outputStream);

            // Close the output stream.
            outputStream.Close();
        }
        catch(pdfcrowd.Error why)
        {
            System.Console.Error.WriteLine("Pdfcrowd Error: " + why);
            throw;
        }
    }
}

Get info about the current conversion

using System;
using System.IO;

public class ApiTest
{
    public static void Main()
    {
        try
        {
            // Create an API client instance.
            pdfcrowd.HtmlToPdfClient client =
                new pdfcrowd.HtmlToPdfClient("demo", "ce544b6ea52a5621fb9d55f8b542d14d");

            // Specify the mapping of HTML content width to the PDF page width.
            // To fine-tune the layout, you can specify an exact viewport width, such as '960px'.
            client.setDebugLog(true);

            // Run the conversion and save the result to a file.
            client.convertFileToFile("/path/to/MyLayout.html", "MyLayout.pdf");
            
            // print URL of the debug log
            System.Console.WriteLine("Debug log url: " + client.getDebugLogUrl());
            
            // print the number of conversion credits remaining in your account
            System.Console.WriteLine("Remaining credit count: " + client.getRemainingCreditCount());
            
            // print the number of credits used for the conversion
            System.Console.WriteLine("Consumed credit count: " + client.getConsumedCreditCount());
            
            // print the unique identifier for the conversion
            System.Console.WriteLine("Job id: " + client.getJobId());
            
            // print total number of pages in the output document
            System.Console.WriteLine("Page count: " + client.getPageCount());
            
            // print size of the output data in bytes
            System.Console.WriteLine("Output size: " + client.getOutputSize());
        }
        catch(pdfcrowd.Error why)
        {
            System.Console.Error.WriteLine("Pdfcrowd Error: " + why);
            throw;
        }
    }
}

Advanced examples

Customize the page size and the orientation

using System;
using System.IO;

public class ApiTest
{
    public static void Main()
    {
        try
        {
            // Create an API client instance.
            pdfcrowd.HtmlToPdfClient client =
                new pdfcrowd.HtmlToPdfClient("demo", "ce544b6ea52a5621fb9d55f8b542d14d");

            // Configure the conversion.
            client.setPageSize("Letter");
            client.setOrientation("landscape");
            client.setNoMargins(true);

            // Run the conversion and save the result to a file.
            client.convertUrlToFile("http://www.example.com", "letter_landscape.pdf");
        }
        catch(pdfcrowd.Error why)
        {
            System.Console.Error.WriteLine("Pdfcrowd Error: " + why);
            throw;
        }
    }
}

Put the source URL in the header and the page number in the footer

using System;
using System.IO;

public class ApiTest
{
    public static void Main()
    {
        try
        {
            // Create an API client instance.
            pdfcrowd.HtmlToPdfClient client =
                new pdfcrowd.HtmlToPdfClient("demo", "ce544b6ea52a5621fb9d55f8b542d14d");

            // Configure the conversion.
            client.setHeaderHeight("15mm");
            client.setFooterHeight("10mm");
            client.setHeaderHtml("<a class='pdfcrowd-source-url' data-pdfcrowd-placement='href-and-content'></a>");
            client.setFooterHtml("<center><span class='pdfcrowd-page-number'></span></center>");
            client.setMarginTop("0");
            client.setMarginBottom("0");

            // Run the conversion and save the result to a file.
            client.convertUrlToFile("http://www.example.com", "header_footer.pdf");
        }
        catch(pdfcrowd.Error why)
        {
            System.Console.Error.WriteLine("Pdfcrowd Error: " + why);
            throw;
        }
    }
}

Create fillable PDF form

using System;
using System.IO;

public class ApiTest
{
    public static void Main()
    {
        try
        {
            // Create an API client instance.
            pdfcrowd.HtmlToPdfClient client =
                new pdfcrowd.HtmlToPdfClient("demo", "ce544b6ea52a5621fb9d55f8b542d14d");

            // Configure the conversion.
            client.setEnablePdfForms(true);

            // Run the conversion and save the result to a file.
            client.convertStringToFile("<html><body>Enter name:<input type=text></body></html>", "form.pdf");
        }
        catch(pdfcrowd.Error why)
        {
            System.Console.Error.WriteLine("Pdfcrowd Error: " + why);
            throw;
        }
    }
}

Zoom the HTML document

using System;
using System.IO;

public class ApiTest
{
    public static void Main()
    {
        try
        {
            // Create an API client instance.
            pdfcrowd.HtmlToPdfClient client =
                new pdfcrowd.HtmlToPdfClient("demo", "ce544b6ea52a5621fb9d55f8b542d14d");

            // Configure the conversion.
            client.setScaleFactor(300);

            // Run the conversion and save the result to a file.
            client.convertUrlToFile("http://www.example.com", "zoom_300.pdf");
        }
        catch(pdfcrowd.Error why)
        {
            System.Console.Error.WriteLine("Pdfcrowd Error: " + why);
            throw;
        }
    }
}

Set PDF metadata

using System;
using System.IO;

public class ApiTest
{
    public static void Main()
    {
        try
        {
            // Create an API client instance.
            pdfcrowd.HtmlToPdfClient client =
                new pdfcrowd.HtmlToPdfClient("demo", "ce544b6ea52a5621fb9d55f8b542d14d");

            // Configure the conversion.
            client.setAuthor("Pdfcrowd");
            client.setTitle("Hello World");
            client.setSubject("Demo");
            client.setKeywords("Pdfcrowd,demo");

            // Run the conversion and save the result to a file.
            client.convertUrlToFile("http://www.example.com", "with_metadata.pdf");
        }
        catch(pdfcrowd.Error why)
        {
            System.Console.Error.WriteLine("Pdfcrowd Error: " + why);
            throw;
        }
    }
}

Create a Powerpoint like presentation from an HTML document

using System;
using System.IO;

public class ApiTest
{
    public static void Main()
    {
        try
        {
            // Create an API client instance.
            pdfcrowd.HtmlToPdfClient client =
                new pdfcrowd.HtmlToPdfClient("demo", "ce544b6ea52a5621fb9d55f8b542d14d");

            // Configure the conversion.
            client.setPageLayout("single-page");
            client.setPageMode("full-screen");
            client.setInitialZoomType("fit-page");
            client.setOrientation("landscape");
            client.setNoMargins(true);

            // Run the conversion and save the result to a file.
            client.convertUrlToFile("https://pdfcrowd.com/api/", "slide_show.pdf");
        }
        catch(pdfcrowd.Error why)
        {
            System.Console.Error.WriteLine("Pdfcrowd Error: " + why);
            throw;
        }
    }
}

Convert an HTML document section

using System;
using System.IO;

public class ApiTest
{
    public static void Main()
    {
        try
        {
            // Create an API client instance.
            pdfcrowd.HtmlToPdfClient client =
                new pdfcrowd.HtmlToPdfClient("demo", "ce544b6ea52a5621fb9d55f8b542d14d");

            // Configure the conversion.
            client.setElementToConvert("#main");

            // Run the conversion and save the result to a file.
            client.convertUrlToFile("https://pdfcrowd.com/api/", "html_part.pdf");
        }
        catch(pdfcrowd.Error why)
        {
            System.Console.Error.WriteLine("Pdfcrowd Error: " + why);
            throw;
        }
    }
}

Inject an HTML code

using System;
using System.IO;

public class ApiTest
{
    public static void Main()
    {
        try
        {
            // Create an API client instance.
            pdfcrowd.HtmlToPdfClient client =
                new pdfcrowd.HtmlToPdfClient("demo", "ce544b6ea52a5621fb9d55f8b542d14d");

            // Configure the conversion.
            client.setCustomJavascript("el=document.createElement('h2'); el.textContent='Hello from Pdfcrowd API'; el.style.color='red'; el_before=document.getElementsByTagName('h1')[0]; el_before.parentNode.insertBefore(el, el_before.nextSibling)");

            // Run the conversion and save the result to a file.
            client.convertUrlToFile("http://www.example.com", "html_inject.pdf");
        }
        catch(pdfcrowd.Error why)
        {
            System.Console.Error.WriteLine("Pdfcrowd Error: " + why);
            throw;
        }
    }
}

Convert a responsive web page as it appears on a large device

using System;
using System.IO;

public class ApiTest
{
    public static void Main()
    {
        try
        {
            // Create an API client instance.
            pdfcrowd.HtmlToPdfClient client =
                new pdfcrowd.HtmlToPdfClient("demo", "ce544b6ea52a5621fb9d55f8b542d14d");

            // Configure the conversion.
            client.setContentViewportWidth("large");
            client.setNoMargins(true);

            // Run the conversion and save the result to a file.
            client.convertUrlToFile("https://getbootstrap.com/", "bootstrap.pdf");
        }
        catch(pdfcrowd.Error why)
        {
            System.Console.Error.WriteLine("Pdfcrowd Error: " + why);
            throw;
        }
    }
}

Create an in-memory archive (ZIP) and convert it

using System;
using System.IO;
using System.IO.Compression;

public class ApiTest
{
    private static void addFileToArchive(String fName, String fPath, ZipArchive archive) {
        var entry = archive.CreateEntry(fName);

        using(var entryStream = entry.Open()) {
            using(var readStream = File.OpenRead(fPath)) {
                pdfcrowd.ConnectionHelper.CopyStream(readStream, entryStream);
            }
        }
    }

    public static void Main()
    {
        try
        {
            // Create an API client instance.
            pdfcrowd.HtmlToPdfClient client =
                new pdfcrowd.HtmlToPdfClient("demo", "ce544b6ea52a5621fb9d55f8b542d14d");

            // Create a ZIP archive.
            MemoryStream inStream = new MemoryStream();
            using(ZipArchive archive = new ZipArchive(inStream, ZipArchiveMode.Create, true))
            {
                // Add HTML content to the archive.
                ZipArchiveEntry htmlEntry = archive.CreateEntry("index.html");
                using (StreamWriter writer = new StreamWriter(htmlEntry.Open()))
                {
                    writer.Write(@"<html>
                        <head>
                            <style>
                             @font-face
                             {
                                 font-family: 'OpenSans';
                                 src: url(fonts/OpenSans.ttf) format('truetype');
                             }
                    
                             h1
                             {
                                 font-family: OpenSans;
                             }
                            </style>
                        </head>
                        <body>
                            <h1>Hello World</h1>
                            <img src='images/logo.png'>
                        </body>
                    </html>");
                }

                // Add required local files to the archive.
                addFileToArchive("fonts/OpenSans.ttf", "/your-path-to/fonts/OpenSans.ttf", archive);
                addFileToArchive("images/logo.png", "/your-path-to/images/logo.png", archive);
            }

            inStream.Seek(0, SeekOrigin.Begin);

            // Create an output stream for the conversion result
            FileStream outputStream = new FileStream("HelloFromZip.pdf", FileMode.CreateNew);

            // run the conversion and write the result to the output stream.
            client.convertStreamToStream(inStream, outputStream);

            // Close the output stream.
            outputStream.Close();
        }
        catch(pdfcrowd.Error why)
        {
            System.Console.Error.WriteLine("Pdfcrowd Error: " + why);
            throw;
        }
    }
}

Renderer debugging - highlight HTML elements

using System;
using System.IO;

public class ApiTest
{
    public static void Main()
    {
        try
        {
            // Create an API client instance.
            pdfcrowd.HtmlToPdfClient client =
                new pdfcrowd.HtmlToPdfClient("demo", "ce544b6ea52a5621fb9d55f8b542d14d");

            // Configure the conversion.
            client.setCustomJavascript("libPdfcrowd.highlightHtmlElements({backgroundColor: 'rgba(255, 191, 0, 0.1)', borderColor:null})");

            // Run the conversion and save the result to a file.
            client.convertUrlToFile("http://www.example.com", "highlight_background.pdf");
        }
        catch(pdfcrowd.Error why)
        {
            System.Console.Error.WriteLine("Pdfcrowd Error: " + why);
            throw;
        }
    }
}

Renderer debugging - borders with spacing around HTML elements

using System;
using System.IO;

public class ApiTest
{
    public static void Main()
    {
        try
        {
            // Create an API client instance.
            pdfcrowd.HtmlToPdfClient client =
                new pdfcrowd.HtmlToPdfClient("demo", "ce544b6ea52a5621fb9d55f8b542d14d");

            // Configure the conversion.
            client.setCustomJavascript("libPdfcrowd.highlightHtmlElements({borderColor: 'orange', backgroundColor: null, padding: '4px', margin: '4px'})");

            // Run the conversion and save the result to a file.
            client.convertUrlToFile("http://www.example.com", "highlight_borders.pdf");
        }
        catch(pdfcrowd.Error why)
        {
            System.Console.Error.WriteLine("Pdfcrowd Error: " + why);
            throw;
        }
    }
}

Template rendering examples

Create PDF from JSON data

using System;
using System.IO;

public class ApiTest
{
    public static void Main()
    {
        try
        {
            // Create an API client instance.
            pdfcrowd.HtmlToPdfClient client =
                new pdfcrowd.HtmlToPdfClient("demo", "ce544b6ea52a5621fb9d55f8b542d14d");

            // Configure the conversion.
            client.setDataString(@"{
            ""name"": ""World"",
            ""product"": ""Pdfcrowd API""
        }");

            // Run the conversion and save the result to a file.
            client.convertStringToFile("Hello {{ name }} from {{ product }}", "output.pdf");
        }
        catch(pdfcrowd.Error why)
        {
            System.Console.Error.WriteLine("Pdfcrowd Error: " + why);
            throw;
        }
    }
}

Create PDF from XML data

using System;
using System.IO;

public class ApiTest
{
    public static void Main()
    {
        try
        {
            // Create an API client instance.
            pdfcrowd.HtmlToPdfClient client =
                new pdfcrowd.HtmlToPdfClient("demo", "ce544b6ea52a5621fb9d55f8b542d14d");

            // Configure the conversion.
            client.setDataString(@"<?xml version=""1.0"" encoding=""UTF-8""?>
        <data>
          <name>World</name>
          <product>Pdfcrowd API</product>
        </data>");

            // Run the conversion and save the result to a file.
            client.convertStringToFile("Hello {{ data.name }} from {{ data.product }}", "output.pdf");
        }
        catch(pdfcrowd.Error why)
        {
            System.Console.Error.WriteLine("Pdfcrowd Error: " + why);
            throw;
        }
    }
}

Create PDF from YAML data

using System;
using System.IO;

public class ApiTest
{
    public static void Main()
    {
        try
        {
            // Create an API client instance.
            pdfcrowd.HtmlToPdfClient client =
                new pdfcrowd.HtmlToPdfClient("demo", "ce544b6ea52a5621fb9d55f8b542d14d");

            // Configure the conversion.
            client.setDataString(@"name: World
product: Pdfcrowd API");

            // Run the conversion and save the result to a file.
            client.convertStringToFile("Hello {{ name }} from {{ product }}", "output.pdf");
        }
        catch(pdfcrowd.Error why)
        {
            System.Console.Error.WriteLine("Pdfcrowd Error: " + why);
            throw;
        }
    }
}

Create PDF from CSV data

using System;
using System.IO;

public class ApiTest
{
    public static void Main()
    {
        try
        {
            // Create an API client instance.
            pdfcrowd.HtmlToPdfClient client =
                new pdfcrowd.HtmlToPdfClient("demo", "ce544b6ea52a5621fb9d55f8b542d14d");

            // Configure the conversion.
            client.setDataString(@"name,product
World,Pdfcrowd API");

            // Run the conversion and save the result to a file.
            client.convertStringToFile("Hello {{ name }} from {{ product }}", "output.pdf");
        }
        catch(pdfcrowd.Error why)
        {
            System.Console.Error.WriteLine("Pdfcrowd Error: " + why);
            throw;
        }
    }
}

ASP.NET Web Forms examples

Webpage to PDF in ASP.NET Web Forms

using System;
using System.IO;
using System.Web;
using System.Web.UI;
using System.Web.Mvc;

namespace PdfcrowdDemo
{
    public partial class Default: System.Web.UI.Page
    {
        protected override void Render(HtmlTextWriter writer)
        {
            try
            {
                // Create an API client instance.
                pdfcrowd.HtmlToPdfClient client =
                    new pdfcrowd.HtmlToPdfClient("demo", "ce544b6ea52a5621fb9d55f8b542d14d");

                // Run the conversion and store the result in the `pdf` variable.
                byte[] pdf = client.convertUrl("http://www.example.com");

                // Set HTTP response headers.
                Response.ContentType = "application/pdf";
                Response.Headers.Add("Cache-Control", "max-age=0");
                Response.Headers.Add("Accept-Ranges", "none");
                Response.Headers.Add("Content-Disposition", "attachment; filename*=UTF-8''" + Uri.EscapeUriString("example.pdf"));

                // Send the result in the HTTP response.
                Response.OutputStream.Write(pdf, 0, pdf.Length);
                Response.Flush();
            }
            catch(pdfcrowd.Error why)
            {
                // Send the error in the HTTP response.
                Response.StatusCode = why.getCode();
                Response.StatusDescription = why.getMessage();
            }
        }
    }
}

HTML file to PDF in ASP.NET Web Forms

using System;
using System.IO;
using System.Web;
using System.Web.UI;
using System.Web.Mvc;

namespace PdfcrowdDemo
{
    public partial class Default: System.Web.UI.Page
    {
        protected override void Render(HtmlTextWriter writer)
        {
            try
            {
                // Create an API client instance.
                pdfcrowd.HtmlToPdfClient client =
                    new pdfcrowd.HtmlToPdfClient("demo", "ce544b6ea52a5621fb9d55f8b542d14d");

                // Run the conversion and store the result in the `pdf` variable.
                byte[] pdf = client.convertFile("/path/to/MyLayout.html");

                // Set HTTP response headers.
                Response.ContentType = "application/pdf";
                Response.Headers.Add("Cache-Control", "max-age=0");
                Response.Headers.Add("Accept-Ranges", "none");
                Response.Headers.Add("Content-Disposition", "attachment; filename*=UTF-8''" + Uri.EscapeUriString("MyLayout.pdf"));

                // Send the result in the HTTP response.
                Response.OutputStream.Write(pdf, 0, pdf.Length);
                Response.Flush();
            }
            catch(pdfcrowd.Error why)
            {
                // Send the error in the HTTP response.
                Response.StatusCode = why.getCode();
                Response.StatusDescription = why.getMessage();
            }
        }
    }
}

HTML string to PDF in ASP.NET Web Forms

using System;
using System.IO;
using System.Web;
using System.Web.UI;
using System.Web.Mvc;

namespace PdfcrowdDemo
{
    public partial class Default: System.Web.UI.Page
    {
        protected override void Render(HtmlTextWriter writer)
        {
            try
            {
                // Create an API client instance.
                pdfcrowd.HtmlToPdfClient client =
                    new pdfcrowd.HtmlToPdfClient("demo", "ce544b6ea52a5621fb9d55f8b542d14d");

                // Run the conversion and store the result in the `pdf` variable.
                byte[] pdf = client.convertString("<html><body><h1>Hello World!</h1></body></html>");

                // Set HTTP response headers.
                Response.ContentType = "application/pdf";
                Response.Headers.Add("Cache-Control", "max-age=0");
                Response.Headers.Add("Accept-Ranges", "none");
                Response.Headers.Add("Content-Disposition", "attachment; filename*=UTF-8''" + Uri.EscapeUriString("HelloWorld.pdf"));

                // Send the result in the HTTP response.
                Response.OutputStream.Write(pdf, 0, pdf.Length);
                Response.Flush();
            }
            catch(pdfcrowd.Error why)
            {
                // Send the error in the HTTP response.
                Response.StatusCode = why.getCode();
                Response.StatusDescription = why.getMessage();
            }
        }
    }
}