How to Convert HTML to PDF in C# Using wkhtmltopdf

This article was first published in March 2023 and was updated in August 2024.

This blog post will go over the steps necessary to convert HTML to PDF using wkhtmltopdf and C#. wkhtmltopdf is an open source command-line tool that uses the WebKit rendering engine to generate high-quality PDFs, offering various options for styling and formatting. Additionally, the post will explore how to integrate PSPDFKit API, a robust tool for PDF generation that supports advanced features like asset management and customization. This tutorial will cover installing wkhtmltopdf, setting up a C# project, and integrating both wkhtmltopdf and PSPDFKit API to convert HTML to PDF.

Development Considerations

Before getting started, it’s important to note that wkhtmltopdf is a command-line tool, and it doesn’t have a built-in graphical user interface (GUI). It’s also an open source tool, created in 2008 by Jakob Truelsen, and it isn’t being consistently maintained at this time.

If you’re considering a commercial solution, PSPDFKit offers some options for you:

• HTML to PDF in C# API — A REST API/hosted solution that gives you 100 free conversions per month and offers additional packages for a per-document fee.

• HTML to PDF in C# — Our self-hosted solution backed by our GdPicture.NET library.

Our solutions are regularly maintained, with releases occurring multiple times throughout the year. We also offer one-on-one support to handle any issues or challenges you may encounter.

Requirements

• Visual Studio Code installed on your machine.

• The C# extension for Visual Studio Code.

Installing wkhtmltopdf

To install wkhtmltopdf, follow the steps for your machine below.

On Windows

1. Download the wkhtmltopdf binary from the official website.

2. Once the download is complete, extract the files to a directory of your choice.

3. Add the directory containing the wkhtmltopdf binary to your system’s PATH environment variable. This will allow you to run the wkhtmltopdf command from anywhere on your system.

4. Verify that wkhtmltopdf is installed correctly by running the following command in your terminal:

where wkhtmltopdf

The wkhtmltopdf executable will be located in the installation directory — by default, it’s C:\Program Files\wkhtmltopdf\bin.

On macOS

1. You can install wkhtmltopdf using Homebrew:

brew install --cask wkhtmltopdf

2. Or, you can download the binary from the official website.

If you choose to download the binary from the official website, you may see an error message that says the following:

“wkhtmltox-0.12.6-2.macos-cocoa.pkg” cannot be opened because it is from an unidentified developer.

This means your Mac’s security settings are preventing you from installing the package.

To install the package, you’ll need to change your security settings to allow installation of packages from unidentified developers. Follow the steps below:

• Right-click the wkhtmltox-0.12.6-2.macos-cocoa.pkg file and select Open.

• A warning message will appear. Click Open.

• The package installer will open. Follow the prompts to complete the installation.

3. Verify that wkhtmltopdf is installed correctly by running the following command in your terminal:

which wkhtmltopdf

The wkhtmltopdf executable will be located in the installation directory — by default, it’s /usr/local/bin.

On Ubuntu

If you’re using Ubuntu, you can install wkhtmltopdf by running the following command:

sudo apt-get install wkhtmltopdf

Setting Up a .NET Console Project in Visual Studio Code

Once it’s installed, follow the steps below to set up a project.

1. Create a new directory for your project and open it in Visual Studio Code.

2. Open the terminal (press Control or Command-backtick `).

3. Run the following command to create a new .NET console project:

dotnet new console --framework net7.0

4. Replace the contents of Program.cs with the following code:

class Program
  {
      static void Main(string[] args)
      {
          Console.WriteLine("Hello, World!");
      }
  }

Integrating wkhtmltopdf with C#

1. Add the following namespace to the top of your Program.cs file:

using System.Diagnostics

The System.Diagnostics namespace provides classes and methods that allow you to interact with system processes, event logs, and performance counters.

2. In your Main method, create a new instance of the ProcessStartInfo class and set the FileName property to the path of the wkhtmltopdf binary:

var processStartInfo = new ProcessStartInfo
        {
            // Pass the path of the wkhtmltopdf executable.
            FileName = "/usr/local/bin/wkhtmltopdf",
        };

You can search for the executable in the file explorer. By default, it’s located in C:\Program Files\wkhtmltopdf\bin on Windows and in /usr/local/bin on Mac.

If you’ve installed wkhtmltopdf using a package manager like apt-get, yum, or brew, you can check the path using these commands:

• On Linux, type whereis wkhtmltopdf.

• On macOS, type brew info wkhtmltopdf.

Another solution is to use the full path of the executable. You can find the full path of the wkhtmltopdf executable by running the following command in your terminal:

find / -name wkhtmltopdf 2>/dev/null

This will search for the executable in the entire file system and print its location.

Once you’ve found the path to the wkhtmltopdf executable, you can use it in the ProcessStartInfo class to run the process.

3. Set the Arguments property to include the input HTML file and the output PDF file, in that order:

var inputHtml = "/Users/<username>/Desktop/<your-project-name>/bin/Debug/net7.0/input.html";
var outputPdf = "output.pdf";

var processStartInfo = new ProcessStartInfo
   {
      FileName = "/usr/local/bin/wkhtmltopdf",
      Arguments = $"{inputHtml} {outputPdf}",
   };

The input.html file must be located in the same directory as the wkhtmltopdf executable. Make sure to use an absolute path to specify the location of the input HTML file and the output PDF file.

For example, you created the input.html file in the /Users/<username>/Desktop/<your-project-name>/bin/Debug/net7.0/input.html directory.

4. Set the UseShellExecute property to false and RedirectStandardOutput to true:

var processStartInfo = new ProcessStartInfo
        {
            // Pass the path of the wkhtmltopdf executable.
            FileName = "/usr/local/bin/wkhtmltopdf",
            Arguments = $"{inputHtml} {outputPdf}",
            UseShellExecute = false,
            RedirectStandardOutput = true,
            WorkingDirectory = AppDomain.CurrentDomain.BaseDirectory
        };

UseShellExecute = false allows the process to be started without creating a new window, and RedirectStandardOutput = true enables the output of the process to be read.

The WorkingDirectory property is used to set the current directory of the process.

AppDomain.CurrentDomain.BaseDirectory is used to set the current directory as the base directory of the application’s domain. This is necessary to ensure that the input and output files are located in the correct directory within the project.

5. Start the process using the Process.Start method, and wait for it to complete using the WaitForExit method:

using (var process = Process.Start(processStartInfo))
        {
            process?.WaitForExit();
            if (process?.ExitCode == 0)
            {
                Console.WriteLine("HTML to PDF conversion successful!");
            }
            else
            {
                Console.WriteLine("HTML to PDF conversion failed!");
                Console.WriteLine(process?.StandardOutput.ReadToEnd());
            }
        }

Once the process exits, check the ExitCode property to see if the conversion was successful. If the ExitCode is 0, it means the conversion was successful, and a success message is printed. If the ExitCode isn’t 0, it means the conversion failed and a failure message is printed, along with the standard output of the process, using the StandardOutput.ReadToEnd() method.

Find the complete code below:

// Program.cs

// See https://aka.ms/new-console-template for more information.
using System.Diagnostics;

class Program
{
    static void Main(string[] args)
    {
        var inputHtml = "/Users/<username>/Desktop/<your-project-name>/bin/Debug/net7.0/input.html";
        var outputPdf = "output.pdf";

        if (!System.IO.File.Exists(inputHtml))
        {
            Console.WriteLine($"{inputHtml} file not found!");
            return;
        }

        var processStartInfo = new ProcessStartInfo
        {
            // Pass the path of the wkhtmltopdf executable.
            FileName = "/usr/local/bin/wkhtmltopdf",
            Arguments = $"{inputHtml} {outputPdf}",
            UseShellExecute = false,
            RedirectStandardOutput = true,
            WorkingDirectory = AppDomain.CurrentDomain.BaseDirectory
        };

        Console.WriteLine($"Starting process with FileName: {processStartInfo.FileName} and Arguments: {processStartInfo.Arguments}");

       using (var process = Process.Start(processStartInfo))
        {
            process?.WaitForExit();
            if (process?.ExitCode == 0)
            {
                Console.WriteLine("HTML to PDF conversion successful!");
            }
            else
            {
                Console.WriteLine("HTML to PDF conversion failed!");
                Console.WriteLine(process?.StandardOutput.ReadToEnd());
            }
        }
    }
}

Running the Project

Run the project using the dotnet run command in the terminal.

Integrating PSPDFKit API with C# for HTML-to-PDF Conversion

In addition to using wkhtmltopdf, you can also leverage the PSPDFKit API to convert HTML to PDF. The PSPDFKit API offers a robust and flexible solution for generating high-quality PDFs with various customization options. Below is a step-by-step guide on how to integrate PSPDFKit API into your C# project.

Setting Up PSPDFKit API

1. First, ensure you have an API key from PSPDFKit API. You’ll use this key to authenticate your requests.

2. Open VS Code.

3. Open a terminal in VS Code (`Control-``).

4. Create a new directory for your project and navigate into it:

mkdir PspdfkitApiDemo
cd PspdfkitApiDemo

5. Initialize a new C# project:

dotnet new console

6. Install the RestSharp package:

dotnet add package RestSharp

6. Replace the contents of Program.cs with the provided code:

using System;
using System.IO;
using System.Net;
using RestSharp;

namespace PspdfkitApiDemo
{
    class Program
    {
        static void Main(string[] args)
        {
            var client = new RestClient("https://api.pspdfkit.com/build");

            var request = new RestRequest(Method.POST)
                .AddHeader("Authorization", "Bearer your_api_key_here")
                .AddFile("index.html", "index.html")
                .AddParameter("instructions", new JsonObject
                {
                    ["parts"] = new JsonArray
                    {
                        new JsonObject
                        {
                            ["html"] = "index.html"
                        }
                    }
                }.ToString());

            request.AdvancedResponseWriter = (responseStream, response) =>
            {
                if (response.StatusCode == HttpStatusCode.OK)
                {
                    using (responseStream)
                    {
                        using var outputFileWriter = File.OpenWrite("result.pdf");
                        responseStream.CopyTo(outputFileWriter);
                    }
                }
                else
                {
                    var responseStreamReader = new StreamReader(responseStream);
                    Console.Write(responseStreamReader.ReadToEnd());
                }
            };

            client.Execute(request);
        }
    }
}

Replace “your_api_key_here” with your actual PSPDFKit API key.

7. Make sure you have index.html in the same directory as your Program.cs file.

8. Run the project using the terminal:

dotnet run

9. Check the output directory for result.pdf to see your newly generated PDF.

Why Use PSPDFKit API?

• SOC 2 Compliant — Build secure workflows with encrypted API endpoints.

• Easy Integration — Well-documented APIs and code samples make integration straightforward.

• Robust and Flexible — Access more than 30 tools to process documents in multiple ways.

• Simple and Transparent Pricing — Choose a package based on your needs, with clear credit costs for each API tool and action.

Conclusion

In this tutorial, you learned how to convert HTML to PDF using wkhtmltopdf and C#. With this tool, you can easily convert HTML files to high-quality PDFs with various options for styling and formatting.

wkhtmltopdf is an open source command-line tool that offers a straightforward method for converting HTML to high-quality PDFs, though it may lack active maintenance.

PSPDFKit API, on the other hand, provides a commercial solution with advanced features and customization options, suitable for more complex PDF needs.

Get started with our API product for free, or integrate a free trial of our .NET PDF library.

FAQ

Here are a few frequently asked questions about converting HTML to PDF using wkhtmltopdf.

What Is wkhtmltopdf?

wkhtmltopdf is an open source command-line tool that converts HTML to PDF using the WebKit rendering engine.

How Can I Convert HTML to PDF in C#?

You can convert HTML to PDF in C# using wkhtmltopdf by calling it from your application or by integrating PSPDFKit API for more advanced features.

What Tools Can Be Used for C# HTML-to-PDF Conversion?

For C# HTML-to-PDF conversion, you can use wkhtmltopdf for a free, open source option or PSPDFKit for a feature-rich, commercial solution.

Can I Use wkhtmltopdf on macOS?

Yes, you can install wkhtmltopdf via Homebrew or by downloading the binary from the official website. If you encounter a security warning, adjust your Mac’s security settings to allow the installation.

What Should I Do If wkhtmltopdf Doesn’t Convert HTML to PDF Successfully?

Ensure the path to wkhtmltopdf and the input/output file paths are correct, and check the process exit code and standard output for error messages.