PRODUCT COMPARISONS

iTextSharp C# HTML to PDF Alternative for .NET Core

Published October 23, 2024

Introduction

A reliable and straightforward tool for manipulating PDFs can streamline many tasks involved in creating and editing PDF documents. In the .NET ecosystem, two popular libraries stand out – IronPDF and iTextSharp – that allow for PDF generation without any Adobe dependencies. Both libraries offer a wide range of features such as creating, editing, and converting PDFs. This article will compare IronPDF and iTextSharp based on three criteria: features, documentation quality, and pricing policies.

Overview of IronPDF and iTextSharp

IronPDF is a prominent .NET PDF library that allows developers to easily create, modify, and interact with PDF documents. It supports various .NET environments, including .NET Core, .NET 8, 7, 6, and Framework, making it highly versatile. Key features of IronPDF include HTML to PDF conversion, merging PDFs, encryption, and digital signatures. The documentation is user-friendly, and technical support is robust.

iTextSharp is a powerful PDF library for the .NET platform, originally derived from iText (which is Java-based). It provides enterprise-level solutions for creating and manipulating PDFs and is available under both open-source (AGPL) and commercial licenses. The iTextSharp core library offers a high degree of flexibility, allowing developers to create PDFs from scratch, manage forms, apply digital signatures, add PDF functionality, and more.

Cross-Platform Compatibility

Both IronPDF and iTextSharp are compatible with multiple platforms. Let’s compare their supported frameworks and environments.

IronPDF:

IronPDF supports a wide range of platforms and environments, ensuring seamless integration and deployment in various systems:

.NET versions:
- (C#, VB.NET, F#)
- .NET Core (8, 7, 6, 5, and 3.1+)
- .NET Standard (2.0+)
- .NET Framework (4.6.2+)
App environments: IronPDF works in app environments including Windows, Linux, Mac, Docker, Azure, and AWS
IDEs: Works with IDEs such as Microsoft Visual Studio and JetBrains Rider & ReSharper
OS and Processors: Supports several different OS & processors including Windows, Mac, Linux, x64, x86, ARM

iTextSharp:

.NET versions: Supports .NET Core (2.x, 3.x), .NET Framework (4.6.1+), .NET 5+.
App environments: Runs on Windows, macOS, Linux, and Docker.
Open Source: Available under AGPL license.

Key Feature Comparison: IronPDF vs. iTextSharp

IronPDF and iTextSharp both offer a range of features and tools that can be used to work with PDF files; the focus of this next section will be to take a closer look at some of these features and how the two libraries compare when it comes to carrying out different PDF-related tasks.

IronPDF

HTML to PDF Conversion: Supports HTML, CSS, JavaScript, and images.
PDF File Manipulation: Split and then merge documents, change the formatting of and edit existing PDF documents
Security: PDF encryption and decryption.
Editing: Add annotations, bookmarks, and outlines.
Templates: Apply headers, footers, and page numbers.
Watermarking: Easily apply text and image watermarks to PDF files; take advantage of its use of HTML/CSS to gain full control over the process.
PDF Stamping: Stamp images and text onto your PDF documents using IronPDF.

For more information on the extensive set of features IronPDF has to offer, visit the IronPDF features page.

iTextSharp:

PDF Creation: Supports creating PDF documents from scratch.
Forms: Create and edit PDF forms.
Digital Signatures: Sign PDF documents.
Compression: Optimize PDF file sizes.
Content Extraction: Extract text and images from PDFs.
Open Source: Available under AGPL license.
Customizability: High level of customization for advanced use cases.

Comparison of PDF Functionality Features Between IronPDF and iTextSharp

HTML to PDF Conversion

Converting HTML content into PDF is a very simple task that is done in many different offices and workspaces. Below are the code examples comparing how IronPDF and iText approach this process.

IronPDF

using IronPdf;

// Disable local disk access or cross-origin requests
Installation.EnableWebSecurity = true;

// Instantiate Renderer
var renderer = new ChromePdfRenderer();

// Create a PDF from an HTML string using C#
var pdf = renderer.RenderHtmlAsPdf("<h1>Hello World</h1>");
pdf.SaveAs("output.pdf");

// Advanced Example with HTML Assets
// Load external html assets: images, CSS and JavaScript.
// An optional BasePath 'C:\site\assets\' is set as the file location to load assets from
var myAdvancedPdf = renderer.RenderHtmlAsPdf("<img src='icons/iron.png'>", @"C:\site\assets\");
myAdvancedPdf.SaveAs("html-with-assets.pdf");

using IronPdf;

// Disable local disk access or cross-origin requests
Installation.EnableWebSecurity = true;

// Instantiate Renderer
var renderer = new ChromePdfRenderer();

// Create a PDF from an HTML string using C#
var pdf = renderer.RenderHtmlAsPdf("<h1>Hello World</h1>");
pdf.SaveAs("output.pdf");

// Advanced Example with HTML Assets
// Load external html assets: images, CSS and JavaScript.
// An optional BasePath 'C:\site\assets\' is set as the file location to load assets from
var myAdvancedPdf = renderer.RenderHtmlAsPdf("<img src='icons/iron.png'>", @"C:\site\assets\");
myAdvancedPdf.SaveAs("html-with-assets.pdf");

Imports IronPdf

' Disable local disk access or cross-origin requests
Installation.EnableWebSecurity = True

' Instantiate Renderer
Dim renderer = New ChromePdfRenderer()

' Create a PDF from an HTML string using C#
Dim pdf = renderer.RenderHtmlAsPdf("<h1>Hello World</h1>")
pdf.SaveAs("output.pdf")

' Advanced Example with HTML Assets
' Load external html assets: images, CSS and JavaScript.
' An optional BasePath 'C:\site\assets\' is set as the file location to load assets from
Dim myAdvancedPdf = renderer.RenderHtmlAsPdf("<img src='icons/iron.png'>", "C:\site\assets\")
myAdvancedPdf.SaveAs("html-with-assets.pdf")

VB C#

iTextSharp

using iText.Html2pdf;

static void Main(string[] args)
  {
    using (FileStream htmlSource = File.Open("input.html", FileMode.Open))
    using (FileStream pdfDest = File.Open("output.pdf", FileMode.Create))
    {
        ConverterProperties converterProperties = new ConverterProperties();
        HtmlConverter.ConvertToPdf(htmlSource, pdfDest, converterProperties);
    }
  }

using iText.Html2pdf;

static void Main(string[] args)
  {
    using (FileStream htmlSource = File.Open("input.html", FileMode.Open))
    using (FileStream pdfDest = File.Open("output.pdf", FileMode.Create))
    {
        ConverterProperties converterProperties = new ConverterProperties();
        HtmlConverter.ConvertToPdf(htmlSource, pdfDest, converterProperties);
    }
  }

Imports iText.Html2pdf

Shared Sub Main(ByVal args() As String)
	Using htmlSource As FileStream = File.Open("input.html", FileMode.Open)
	Using pdfDest As FileStream = File.Open("output.pdf", FileMode.Create)
		Dim converterProperties As New ConverterProperties()
		HtmlConverter.ConvertToPdf(htmlSource, pdfDest, converterProperties)
	End Using
	End Using
End Sub

VB C#

When converting HTML to PDF, IronPDF offers a concise and convenient tool for carrying out this task. Utilizing the ChromePdfRenderer to convert HTML content into PDFs, IronPDF excels in providing users with pixel-perfect PDF documents. Users can create PDFs directly from HTML strings, as shown in the first example, or include external assets like images with an optional base path, as demonstrated in the advanced example. iTextSharp, on the other hand, uses HtmlConverter to convert HTML files, but the process requires more setup.

Encrypting PDF Files

Encryption and decryption of PDF documents are vital at many workplaces. To handle this task easily it's necessary to have a tool that can do it conveniently. In the code below, we will see how iTextSharp and IronPDF tackle the encryption of PDFs.

IronPDF

using IronPdf;
using System;

// Open an Encrypted File, alternatively create a new PDF from Html
var pdf = PdfDocument.FromFile("encrypted.pdf", "password");

// Edit file metadata
pdf.MetaData.Author = "Satoshi Nakamoto";
pdf.MetaData.Keywords = "SEO, Friendly";
pdf.MetaData.ModifiedDate = DateTime.Now;

// Edit file security settings
// The following code makes a PDF read only and will disallow copy & paste and printing
pdf.SecuritySettings.RemovePasswordsAndEncryption();
pdf.SecuritySettings.MakePdfDocumentReadOnly("secret-key");
pdf.SecuritySettings.AllowUserAnnotations = false;
pdf.SecuritySettings.AllowUserCopyPasteContent = false;
pdf.SecuritySettings.AllowUserFormData = false;
pdf.SecuritySettings.AllowUserPrinting = IronPdf.Security.PdfPrintSecurity.FullPrintRights;

// change or set the document encryption password
pdf.Password = "my-password";
pdf.SaveAs("secured.pdf");

using IronPdf;
using System;

// Open an Encrypted File, alternatively create a new PDF from Html
var pdf = PdfDocument.FromFile("encrypted.pdf", "password");

// Edit file metadata
pdf.MetaData.Author = "Satoshi Nakamoto";
pdf.MetaData.Keywords = "SEO, Friendly";
pdf.MetaData.ModifiedDate = DateTime.Now;

// Edit file security settings
// The following code makes a PDF read only and will disallow copy & paste and printing
pdf.SecuritySettings.RemovePasswordsAndEncryption();
pdf.SecuritySettings.MakePdfDocumentReadOnly("secret-key");
pdf.SecuritySettings.AllowUserAnnotations = false;
pdf.SecuritySettings.AllowUserCopyPasteContent = false;
pdf.SecuritySettings.AllowUserFormData = false;
pdf.SecuritySettings.AllowUserPrinting = IronPdf.Security.PdfPrintSecurity.FullPrintRights;

// change or set the document encryption password
pdf.Password = "my-password";
pdf.SaveAs("secured.pdf");

Imports IronPdf
Imports System

' Open an Encrypted File, alternatively create a new PDF from Html
Private pdf = PdfDocument.FromFile("encrypted.pdf", "password")

' Edit file metadata
pdf.MetaData.Author = "Satoshi Nakamoto"
pdf.MetaData.Keywords = "SEO, Friendly"
pdf.MetaData.ModifiedDate = DateTime.Now

' Edit file security settings
' The following code makes a PDF read only and will disallow copy & paste and printing
pdf.SecuritySettings.RemovePasswordsAndEncryption()
pdf.SecuritySettings.MakePdfDocumentReadOnly("secret-key")
pdf.SecuritySettings.AllowUserAnnotations = False
pdf.SecuritySettings.AllowUserCopyPasteContent = False
pdf.SecuritySettings.AllowUserFormData = False
pdf.SecuritySettings.AllowUserPrinting = IronPdf.Security.PdfPrintSecurity.FullPrintRights

' change or set the document encryption password
pdf.Password = "my-password"
pdf.SaveAs("secured.pdf")

VB C#

iTextSharp

using System;
using System.IO;
using System.Text;
using iText.Kernel.Pdf;

public class EncryptPdf
    {
        public static readonly String DEST = "results/sandbox/security/encrypt_pdf.pdf";
        public static readonly String SRC = "../../../resources/pdfs/hello.pdf";

        public static readonly String OWNER_PASSWORD = "World";
        public static readonly String USER_PASSWORD = "Hello";

        public static void Main(String[] args)
        {
            FileInfo file = new FileInfo(DEST);
            file.Directory.Create();

            new EncryptPdf().ManipulatePdf(DEST);
        }

        protected void ManipulatePdf(String dest)
        {
            PdfDocument document = new PdfDocument(new PdfReader(SRC), new PdfWriter(dest,
                new WriterProperties().SetStandardEncryption(
                    Encoding.UTF8.GetBytes(USER_PASSWORD),
                    Encoding.UTF8.GetBytes(OWNER_PASSWORD),
                    EncryptionConstants.ALLOW_PRINTING,
                    EncryptionConstants.ENCRYPTION_AES_128 | EncryptionConstants.DO_NOT_ENCRYPT_METADATA
                )));
            document.Close();
        }
    }

using System;
using System.IO;
using System.Text;
using iText.Kernel.Pdf;

public class EncryptPdf
    {
        public static readonly String DEST = "results/sandbox/security/encrypt_pdf.pdf";
        public static readonly String SRC = "../../../resources/pdfs/hello.pdf";

        public static readonly String OWNER_PASSWORD = "World";
        public static readonly String USER_PASSWORD = "Hello";

        public static void Main(String[] args)
        {
            FileInfo file = new FileInfo(DEST);
            file.Directory.Create();

            new EncryptPdf().ManipulatePdf(DEST);
        }

        protected void ManipulatePdf(String dest)
        {
            PdfDocument document = new PdfDocument(new PdfReader(SRC), new PdfWriter(dest,
                new WriterProperties().SetStandardEncryption(
                    Encoding.UTF8.GetBytes(USER_PASSWORD),
                    Encoding.UTF8.GetBytes(OWNER_PASSWORD),
                    EncryptionConstants.ALLOW_PRINTING,
                    EncryptionConstants.ENCRYPTION_AES_128 | EncryptionConstants.DO_NOT_ENCRYPT_METADATA
                )));
            document.Close();
        }
    }

Imports System
Imports System.IO
Imports System.Text
Imports iText.Kernel.Pdf

Public Class EncryptPdf
		Public Shared ReadOnly DEST As String = "results/sandbox/security/encrypt_pdf.pdf"
		Public Shared ReadOnly SRC As String = "../../../resources/pdfs/hello.pdf"

		Public Shared ReadOnly OWNER_PASSWORD As String = "World"
		Public Shared ReadOnly USER_PASSWORD As String = "Hello"

		Public Shared Sub Main(ByVal args() As String)
			Dim file As New FileInfo(DEST)
			file.Directory.Create()

			Call (New EncryptPdf()).ManipulatePdf(DEST)
		End Sub

		Protected Sub ManipulatePdf(ByVal dest As String)
			Dim document As New PdfDocument(New PdfReader(SRC), New PdfWriter(dest, (New WriterProperties()).SetStandardEncryption(Encoding.UTF8.GetBytes(USER_PASSWORD), Encoding.UTF8.GetBytes(OWNER_PASSWORD), EncryptionConstants.ALLOW_PRINTING, EncryptionConstants.ENCRYPTION_AES_128 Or EncryptionConstants.DO_NOT_ENCRYPT_METADATA)))
			document.Close()
		End Sub
End Class

VB C#

IronPDF offers users a straightforward way to encrypt PDF files while also giving users plenty of control of the process, including editing metadata and adjusting security settings such as making documents read-only or restricting user actions like copy and paste. On the other hand, iTextSharp provides more granular control but requires additional configuration, such as specifying encryption standards and permissions.

Redact PDF Content

Occasionally, while handling confidential or private information, it may be necessary to redact portions of a PDF file. The following examples demonstrate how you can redact text using IronPDF in comparison with iTextSharp.

IronPDF

using IronPdf;

PdfDocument pdf = PdfDocument.FromFile("novel.pdf");

// Redact 'are' phrase from all pages
pdf.RedactTextOnAllPages("are");

pdf.SaveAs("redacted.pdf");

using IronPdf;

PdfDocument pdf = PdfDocument.FromFile("novel.pdf");

// Redact 'are' phrase from all pages
pdf.RedactTextOnAllPages("are");

pdf.SaveAs("redacted.pdf");

Imports IronPdf

Private pdf As PdfDocument = PdfDocument.FromFile("novel.pdf")

' Redact 'are' phrase from all pages
pdf.RedactTextOnAllPages("are")

pdf.SaveAs("redacted.pdf")

VB C#

iTextSharp

using System;
using System.IO;
using iText.Kernel.Pdf;
using iText.Layout;
using iText.Layout.Element;
using iText.Layout.Properties;
using iText.Kernel.Colors;

string src = "input.pdf";
string dest = "output_redacted.pdf";

using (PdfReader reader = new PdfReader(src))
            {
                using (PdfWriter writer = new PdfWriter(dest))
                {
                    using (PdfDocument pdfDoc = new PdfDocument(reader, writer))
                    {
                        // Iterate through each page
                        for (int pageNum = 1; pageNum <= pdfDoc.GetNumberOfPages(); pageNum++)
                        {
                            PdfPage page = pdfDoc.GetPage(pageNum);
                            PdfCanvas canvas = new PdfCanvas(page);
                            Rectangle[] rectanglesToRedact = { new Rectangle(100, 100, 200, 50) }; // Example: Define rectangles to redact

                            // Overlay black rectangles to simulate redaction
                            foreach (Rectangle rect in rectanglesToRedact)
                            {
                                canvas.SetFillColor(ColorConstants.BLACK)
                                    .Rectangle(rect.GetX(), rect.GetY(), rect.GetWidth(), rect.GetHeight())
                                    .Fill();
                            }
                        }
                    }
                }

using System;
using System.IO;
using iText.Kernel.Pdf;
using iText.Layout;
using iText.Layout.Element;
using iText.Layout.Properties;
using iText.Kernel.Colors;

string src = "input.pdf";
string dest = "output_redacted.pdf";

using (PdfReader reader = new PdfReader(src))
            {
                using (PdfWriter writer = new PdfWriter(dest))
                {
                    using (PdfDocument pdfDoc = new PdfDocument(reader, writer))
                    {
                        // Iterate through each page
                        for (int pageNum = 1; pageNum <= pdfDoc.GetNumberOfPages(); pageNum++)
                        {
                            PdfPage page = pdfDoc.GetPage(pageNum);
                            PdfCanvas canvas = new PdfCanvas(page);
                            Rectangle[] rectanglesToRedact = { new Rectangle(100, 100, 200, 50) }; // Example: Define rectangles to redact

                            // Overlay black rectangles to simulate redaction
                            foreach (Rectangle rect in rectanglesToRedact)
                            {
                                canvas.SetFillColor(ColorConstants.BLACK)
                                    .Rectangle(rect.GetX(), rect.GetY(), rect.GetWidth(), rect.GetHeight())
                                    .Fill();
                            }
                        }
                    }
                }

Imports System
Imports System.IO
Imports iText.Kernel.Pdf
Imports iText.Layout
Imports iText.Layout.Element
Imports iText.Layout.Properties
Imports iText.Kernel.Colors

Private src As String = "input.pdf"
Private dest As String = "output_redacted.pdf"

Using reader As New PdfReader(src)
				Using writer As New PdfWriter(dest)
					Using pdfDoc As New PdfDocument(reader, writer)
						' Iterate through each page
						Dim pageNum As Integer = 1
						Do While pageNum <= pdfDoc.GetNumberOfPages()
							Dim page As PdfPage = pdfDoc.GetPage(pageNum)
							Dim canvas As New PdfCanvas(page)
							Dim rectanglesToRedact() As Rectangle = { New Rectangle(100, 100, 200, 50) } ' Example: Define rectangles to redact

							' Overlay black rectangles to simulate redaction
							For Each rect As Rectangle In rectanglesToRedact
								canvas.SetFillColor(ColorConstants.BLACK).Rectangle(rect.GetX(), rect.GetY(), rect.GetWidth(), rect.GetHeight()).Fill()
							Next rect
							pageNum += 1
						Loop
					End Using
				End Using

VB C#

IronPDF's redaction tool is concise and easy to use, needing only a few lines of code to streamline the redaction process. This helps raise efficiency around PDF redaction tasks and gives users an easy way to keep their sensitive and private data safe.

On the other hand, iTextSharp lacks a built-in redaction feature, requiring you to manually draw black rectangles over the content you wish to redact. However, this approach can leave the text under the rectangle accessible, allowing users to copy-paste the hidden data, so it doesn’t provide true redaction.

Signing PDF documents

Being able to sign digital documents such as PDF files and then making it an automated process could be time saving. The following code snippets compare how IronPDF and iTextSharp handle digital signatures.

IronPDF

using IronPdf;
using IronPdf.Signing;
using System.Security.Cryptography.X509Certificates;

// Create X509Certificate2 object with X509KeyStorageFlags set to Exportable
X509Certificate2 cert = new X509Certificate2("IronSoftware.pfx", "123456", X509KeyStorageFlags.Exportable);

// Create PdfSignature object
var sig = new PdfSignature(cert);

// Sign PDF document
PdfDocument pdf = PdfDocument.FromFile("document.pdf");
pdf.Sign(sig);
pdf.SaveAs("signed.pdf");

using IronPdf;
using IronPdf.Signing;
using System.Security.Cryptography.X509Certificates;

// Create X509Certificate2 object with X509KeyStorageFlags set to Exportable
X509Certificate2 cert = new X509Certificate2("IronSoftware.pfx", "123456", X509KeyStorageFlags.Exportable);

// Create PdfSignature object
var sig = new PdfSignature(cert);

// Sign PDF document
PdfDocument pdf = PdfDocument.FromFile("document.pdf");
pdf.Sign(sig);
pdf.SaveAs("signed.pdf");

Imports IronPdf
Imports IronPdf.Signing
Imports System.Security.Cryptography.X509Certificates

' Create X509Certificate2 object with X509KeyStorageFlags set to Exportable
Private cert As New X509Certificate2("IronSoftware.pfx", "123456", X509KeyStorageFlags.Exportable)

' Create PdfSignature object
Private sig = New PdfSignature(cert)

' Sign PDF document
Private pdf As PdfDocument = PdfDocument.FromFile("document.pdf")
pdf.Sign(sig)
pdf.SaveAs("signed.pdf")

VB C#

iTextSharp

using System;
using System.IO;
using iText.Kernel.Pdf;
using iText.Signatures;
using Org.BouncyCastle.Crypto;
using Org.BouncyCastle.Pkcs;
using Org.BouncyCastle.X509;

class Program
{
    static void Main(string[] args)
    {
        string src = "input.pdf";
        string dest = "output_signed.pdf";
        string pfxFile = "your_certificate.pfx";
        string pfxPassword = "your_password";

        try
        {
            // Load your certificate
            Pkcs12Store ks = new Pkcs12Store(new FileStream(pfxFile, FileMode.Open), pfxPassword.ToCharArray());
            string alias = null;
            foreach (string al in ks.Aliases)
            {
                if (ks.IsKeyEntry(al))
                {
                    alias = al;
                    break;
                }
            }
            ICipherParameters pk = ks.GetKey(alias).Key;
            X509CertificateEntry[] chain = ks.GetCertificateChain(alias);
            X509Certificate2 cert = new X509Certificate2(chain[0].Certificate.GetEncoded());

            // Create output PDF with signed content
            using (PdfReader reader = new PdfReader(src))
            {
                using (PdfWriter writer = new PdfWriter(dest))
                {
                    using (PdfDocument pdfDoc = new PdfDocument(reader, writer))
                    {
                        // Create the signer
                        PdfSigner signer = new PdfSigner(pdfDoc, writer, new StampingProperties().UseAppendMode());

                        // Configure signature appearance
                        PdfSignatureAppearance appearance = signer.GetSignatureAppearance();
                        appearance.SetReason("Digital Signature");
                        appearance.SetLocation("Your Location");
                        appearance.SetContact("Your Contact");

                        // Create signature
                        IExternalSignature pks = new PrivateKeySignature(pk, "SHA-256");
                        signer.SignDetached(pks, chain, null, null, null, 0, PdfSigner.CryptoStandard.CMS);
                    }
                }
            }
            Console.WriteLine($"PDF digitally signed successfully: {dest}");
        }
        catch (Exception ex)
        {
            Console.WriteLine($"Error signing PDF: {ex.Message}");
        }
    }
}

using System;
using System.IO;
using iText.Kernel.Pdf;
using iText.Signatures;
using Org.BouncyCastle.Crypto;
using Org.BouncyCastle.Pkcs;
using Org.BouncyCastle.X509;

class Program
{
    static void Main(string[] args)
    {
        string src = "input.pdf";
        string dest = "output_signed.pdf";
        string pfxFile = "your_certificate.pfx";
        string pfxPassword = "your_password";

        try
        {
            // Load your certificate
            Pkcs12Store ks = new Pkcs12Store(new FileStream(pfxFile, FileMode.Open), pfxPassword.ToCharArray());
            string alias = null;
            foreach (string al in ks.Aliases)
            {
                if (ks.IsKeyEntry(al))
                {
                    alias = al;
                    break;
                }
            }
            ICipherParameters pk = ks.GetKey(alias).Key;
            X509CertificateEntry[] chain = ks.GetCertificateChain(alias);
            X509Certificate2 cert = new X509Certificate2(chain[0].Certificate.GetEncoded());

            // Create output PDF with signed content
            using (PdfReader reader = new PdfReader(src))
            {
                using (PdfWriter writer = new PdfWriter(dest))
                {
                    using (PdfDocument pdfDoc = new PdfDocument(reader, writer))
                    {
                        // Create the signer
                        PdfSigner signer = new PdfSigner(pdfDoc, writer, new StampingProperties().UseAppendMode());

                        // Configure signature appearance
                        PdfSignatureAppearance appearance = signer.GetSignatureAppearance();
                        appearance.SetReason("Digital Signature");
                        appearance.SetLocation("Your Location");
                        appearance.SetContact("Your Contact");

                        // Create signature
                        IExternalSignature pks = new PrivateKeySignature(pk, "SHA-256");
                        signer.SignDetached(pks, chain, null, null, null, 0, PdfSigner.CryptoStandard.CMS);
                    }
                }
            }
            Console.WriteLine($"PDF digitally signed successfully: {dest}");
        }
        catch (Exception ex)
        {
            Console.WriteLine($"Error signing PDF: {ex.Message}");
        }
    }
}

Imports System
Imports System.IO
Imports iText.Kernel.Pdf
Imports iText.Signatures
Imports Org.BouncyCastle.Crypto
Imports Org.BouncyCastle.Pkcs
Imports Org.BouncyCastle.X509

Friend Class Program
	Shared Sub Main(ByVal args() As String)
		Dim src As String = "input.pdf"
		Dim dest As String = "output_signed.pdf"
		Dim pfxFile As String = "your_certificate.pfx"
		Dim pfxPassword As String = "your_password"

		Try
			' Load your certificate
			Dim ks As New Pkcs12Store(New FileStream(pfxFile, FileMode.Open), pfxPassword.ToCharArray())
			Dim [alias] As String = Nothing
			For Each al As String In ks.Aliases
				If ks.IsKeyEntry(al) Then
					[alias] = al
					Exit For
				End If
			Next al
			Dim pk As ICipherParameters = ks.GetKey([alias]).Key
			Dim chain() As X509CertificateEntry = ks.GetCertificateChain([alias])
			Dim cert As New X509Certificate2(chain(0).Certificate.GetEncoded())

			' Create output PDF with signed content
			Using reader As New PdfReader(src)
				Using writer As New PdfWriter(dest)
					Using pdfDoc As New PdfDocument(reader, writer)
						' Create the signer
						Dim signer As New PdfSigner(pdfDoc, writer, (New StampingProperties()).UseAppendMode())

						' Configure signature appearance
						Dim appearance As PdfSignatureAppearance = signer.GetSignatureAppearance()
						appearance.SetReason("Digital Signature")
						appearance.SetLocation("Your Location")
						appearance.SetContact("Your Contact")

						' Create signature
						Dim pks As IExternalSignature = New PrivateKeySignature(pk, "SHA-256")
						signer.SignDetached(pks, chain, Nothing, Nothing, Nothing, 0, PdfSigner.CryptoStandard.CMS)
					End Using
				End Using
			End Using
			Console.WriteLine($"PDF digitally signed successfully: {dest}")
		Catch ex As Exception
			Console.WriteLine($"Error signing PDF: {ex.Message}")
		End Try
	End Sub
End Class

VB C#

When applying signatures to PDF files digitally, IronPDF presents a condense yet powerful tool for completing this process. Its simplicity allows for the process to be conducted quickly, saving time for any developer who implements it for their signing needs. In contrast, iTextSharp requires more setup and involves additional steps to handle digital signatures, making it more complex, though potentially more flexible for advanced users.

Applying Watermarks to PDF documents

The ability to add and personalize watermarks on PDFs through software can greatly assist with confidentiality, copyright protection, branding or any other tasks involving sensitive information. The following is a comparison of how IronPDF and iTextSharp apply watermarks to PDF files.

IronPDF

using IronPdf;

// Stamps a Watermark onto a new or existing PDF
var renderer = new ChromePdfRenderer();

var pdf = renderer.RenderUrlAsPdf("https://www.nuget.org/packages/IronPdf");
pdf.ApplyWatermark("<h2 style='color:red'>SAMPLE</h2>", 30, IronPdf.Editing.VerticalAlignment.Middle, IronPdf.Editing.HorizontalAlignment.Center);
pdf.SaveAs(@"C:\Path\To\Watermarked.pdf");

using IronPdf;

// Stamps a Watermark onto a new or existing PDF
var renderer = new ChromePdfRenderer();

var pdf = renderer.RenderUrlAsPdf("https://www.nuget.org/packages/IronPdf");
pdf.ApplyWatermark("<h2 style='color:red'>SAMPLE</h2>", 30, IronPdf.Editing.VerticalAlignment.Middle, IronPdf.Editing.HorizontalAlignment.Center);
pdf.SaveAs(@"C:\Path\To\Watermarked.pdf");

Imports IronPdf

' Stamps a Watermark onto a new or existing PDF
Private renderer = New ChromePdfRenderer()

Private pdf = renderer.RenderUrlAsPdf("https://www.nuget.org/packages/IronPdf")
pdf.ApplyWatermark("<h2 style='color:red'>SAMPLE</h2>", 30, IronPdf.Editing.VerticalAlignment.Middle, IronPdf.Editing.HorizontalAlignment.Center)
pdf.SaveAs("C:\Path\To\Watermarked.pdf")

VB C#

iTextSharp

using iText.IO.Font;
using iText.IO.Font.Constants;
using iText.Kernel.Colors;
using iText.Kernel.Font;
using iText.Kernel.Pdf;
using iText.Kernel.Pdf.Canvas;
using iText.Kernel.Pdf.Extgstate;
using iText.Layout;
using iText.Layout.Element;
using iText.Layout.Properties;

public class TransparentWatermark 
    {
        public static readonly String DEST = "results/sandbox/stamper/transparent_watermark.pdf";
        public static readonly String SRC = "../../../resources/pdfs/hero.pdf";

        public static void Main(String[] args) 
        {
            FileInfo file = new FileInfo(DEST);
            file.Directory.Create();

            new TransparentWatermark().ManipulatePdf(DEST);
        }

        protected void ManipulatePdf(String dest) 
        {
            PdfDocument pdfDoc = new PdfDocument(new PdfReader(SRC), new PdfWriter(dest));
            PdfCanvas under = new PdfCanvas(pdfDoc.GetFirstPage().NewContentStreamBefore(), new PdfResources(), pdfDoc);
            PdfFont font = PdfFontFactory.CreateFont(FontProgramFactory.CreateFont(StandardFonts.HELVETICA));
            Paragraph paragraph = new Paragraph("This watermark is added UNDER the existing content")
                    .SetFont(font)
                    .SetFontSize(15);

            Canvas canvasWatermark1 = new Canvas(under, pdfDoc.GetDefaultPageSize())
                    .ShowTextAligned(paragraph, 297, 550, 1, TextAlignment.CENTER, VerticalAlignment.TOP, 0);
            canvasWatermark1.Close();
            PdfCanvas over = new PdfCanvas(pdfDoc.GetFirstPage());
            over.SetFillColor(ColorConstants.BLACK);
            paragraph = new Paragraph("This watermark is added ON TOP OF the existing content")
                    .SetFont(font)
                    .SetFontSize(15);

            Canvas canvasWatermark2 = new Canvas(over, pdfDoc.GetDefaultPageSize())
                    .ShowTextAligned(paragraph, 297, 500, 1, TextAlignment.CENTER, VerticalAlignment.TOP, 0);
            canvasWatermark2.Close();
            paragraph = new Paragraph("This TRANSPARENT watermark is added ON TOP OF the existing content")
                    .SetFont(font)
                    .SetFontSize(15);
            over.SaveState();

            // Creating a dictionary that maps resource names to graphics state parameter dictionaries
            PdfExtGState gs1 = new PdfExtGState();
            gs1.SetFillOpacity(0.5f);
            over.SetExtGState(gs1);
            Canvas canvasWatermark3 = new Canvas(over, pdfDoc.GetDefaultPageSize())
                    .ShowTextAligned(paragraph, 297, 450, 1, TextAlignment.CENTER, VerticalAlignment.TOP, 0);
            canvasWatermark3.Close();
            over.RestoreState();

            pdfDoc.Close();
        }
    }

using iText.IO.Font;
using iText.IO.Font.Constants;
using iText.Kernel.Colors;
using iText.Kernel.Font;
using iText.Kernel.Pdf;
using iText.Kernel.Pdf.Canvas;
using iText.Kernel.Pdf.Extgstate;
using iText.Layout;
using iText.Layout.Element;
using iText.Layout.Properties;

public class TransparentWatermark 
    {
        public static readonly String DEST = "results/sandbox/stamper/transparent_watermark.pdf";
        public static readonly String SRC = "../../../resources/pdfs/hero.pdf";

        public static void Main(String[] args) 
        {
            FileInfo file = new FileInfo(DEST);
            file.Directory.Create();

            new TransparentWatermark().ManipulatePdf(DEST);
        }

        protected void ManipulatePdf(String dest) 
        {
            PdfDocument pdfDoc = new PdfDocument(new PdfReader(SRC), new PdfWriter(dest));
            PdfCanvas under = new PdfCanvas(pdfDoc.GetFirstPage().NewContentStreamBefore(), new PdfResources(), pdfDoc);
            PdfFont font = PdfFontFactory.CreateFont(FontProgramFactory.CreateFont(StandardFonts.HELVETICA));
            Paragraph paragraph = new Paragraph("This watermark is added UNDER the existing content")
                    .SetFont(font)
                    .SetFontSize(15);

            Canvas canvasWatermark1 = new Canvas(under, pdfDoc.GetDefaultPageSize())
                    .ShowTextAligned(paragraph, 297, 550, 1, TextAlignment.CENTER, VerticalAlignment.TOP, 0);
            canvasWatermark1.Close();
            PdfCanvas over = new PdfCanvas(pdfDoc.GetFirstPage());
            over.SetFillColor(ColorConstants.BLACK);
            paragraph = new Paragraph("This watermark is added ON TOP OF the existing content")
                    .SetFont(font)
                    .SetFontSize(15);

            Canvas canvasWatermark2 = new Canvas(over, pdfDoc.GetDefaultPageSize())
                    .ShowTextAligned(paragraph, 297, 500, 1, TextAlignment.CENTER, VerticalAlignment.TOP, 0);
            canvasWatermark2.Close();
            paragraph = new Paragraph("This TRANSPARENT watermark is added ON TOP OF the existing content")
                    .SetFont(font)
                    .SetFontSize(15);
            over.SaveState();

            // Creating a dictionary that maps resource names to graphics state parameter dictionaries
            PdfExtGState gs1 = new PdfExtGState();
            gs1.SetFillOpacity(0.5f);
            over.SetExtGState(gs1);
            Canvas canvasWatermark3 = new Canvas(over, pdfDoc.GetDefaultPageSize())
                    .ShowTextAligned(paragraph, 297, 450, 1, TextAlignment.CENTER, VerticalAlignment.TOP, 0);
            canvasWatermark3.Close();
            over.RestoreState();

            pdfDoc.Close();
        }
    }

Imports iText.IO.Font
Imports iText.IO.Font.Constants
Imports iText.Kernel.Colors
Imports iText.Kernel.Font
Imports iText.Kernel.Pdf
Imports iText.Kernel.Pdf.Canvas
Imports iText.Kernel.Pdf.Extgstate
Imports iText.Layout
Imports iText.Layout.Element
Imports iText.Layout.Properties

Public Class TransparentWatermark
		Public Shared ReadOnly DEST As String = "results/sandbox/stamper/transparent_watermark.pdf"
		Public Shared ReadOnly SRC As String = "../../../resources/pdfs/hero.pdf"

		Public Shared Sub Main(ByVal args() As String)
			Dim file As New FileInfo(DEST)
			file.Directory.Create()

			Call (New TransparentWatermark()).ManipulatePdf(DEST)
		End Sub

		Protected Sub ManipulatePdf(ByVal dest As String)
			Dim pdfDoc As New PdfDocument(New PdfReader(SRC), New PdfWriter(dest))
			Dim under As New PdfCanvas(pdfDoc.GetFirstPage().NewContentStreamBefore(), New PdfResources(), pdfDoc)
			Dim font As PdfFont = PdfFontFactory.CreateFont(FontProgramFactory.CreateFont(StandardFonts.HELVETICA))
			Dim paragraph As Paragraph = (New Paragraph("This watermark is added UNDER the existing content")).SetFont(font).SetFontSize(15)

			Dim canvasWatermark1 As Canvas = (New Canvas(under, pdfDoc.GetDefaultPageSize())).ShowTextAligned(paragraph, 297, 550, 1, TextAlignment.CENTER, VerticalAlignment.TOP, 0)
			canvasWatermark1.Close()
			Dim over As New PdfCanvas(pdfDoc.GetFirstPage())
			over.SetFillColor(ColorConstants.BLACK)
			paragraph = (New Paragraph("This watermark is added ON TOP OF the existing content")).SetFont(font).SetFontSize(15)

			Dim canvasWatermark2 As Canvas = (New Canvas(over, pdfDoc.GetDefaultPageSize())).ShowTextAligned(paragraph, 297, 500, 1, TextAlignment.CENTER, VerticalAlignment.TOP, 0)
			canvasWatermark2.Close()
			paragraph = (New Paragraph("This TRANSPARENT watermark is added ON TOP OF the existing content")).SetFont(font).SetFontSize(15)
			over.SaveState()

			' Creating a dictionary that maps resource names to graphics state parameter dictionaries
			Dim gs1 As New PdfExtGState()
			gs1.SetFillOpacity(0.5F)
			over.SetExtGState(gs1)
			Dim canvasWatermark3 As Canvas = (New Canvas(over, pdfDoc.GetDefaultPageSize())).ShowTextAligned(paragraph, 297, 450, 1, TextAlignment.CENTER, VerticalAlignment.TOP, 0)
			canvasWatermark3.Close()
			over.RestoreState()

			pdfDoc.Close()
		End Sub
End Class

VB C#

IronPDF's easy and intuitive API lets users apply custom watermarks to their PDF files quickly, while giving them full control over the process. Its use of HTML/CSS further simplifies the process without losing any control over the customization. iTextSharp's approach to adding watermarks to PDFs requires more manual work to carry out the task, which can slow the process down.

Stamping Images and Text onto a PDF

There are moments when PDF pages need to be stamped with content, similar to how one might need to apply watermarks to their PDF files. Let's see how IronPDF compares with iTextSharp:

IronPDF

using IronPdf;
using IronPdf.Editing;

ChromePdfRenderer renderer = new ChromePdfRenderer();

PdfDocument pdf = renderer.RenderHtmlAsPdf("<h1>Example HTML Document!</h1>");

// Create text stamper
TextStamper textStamper = new TextStamper()
{
    Text = "Text Stamper!",
    FontFamily = "Bungee Spice",
    UseGoogleFont = true,
    FontSize = 30,
    IsBold = true,
    IsItalic = true,
    VerticalAlignment = VerticalAlignment.Top,
};

// Stamp the text stamper
pdf.ApplyStamp(textStamper);
pdf.SaveAs("stampText.pdf");

// Create image stamper
ImageStamper imageStamper = new ImageStamper(new Uri("https://ironpdf.com/img/svgs/iron-pdf-logo.svg"))
{
    VerticalAlignment = VerticalAlignment.Top,
};

// Stamp the image stamper
pdf.ApplyStamp(imageStamper, 0);
pdf.SaveAs("stampImage.pdf");

using IronPdf;
using IronPdf.Editing;

ChromePdfRenderer renderer = new ChromePdfRenderer();

PdfDocument pdf = renderer.RenderHtmlAsPdf("<h1>Example HTML Document!</h1>");

// Create text stamper
TextStamper textStamper = new TextStamper()
{
    Text = "Text Stamper!",
    FontFamily = "Bungee Spice",
    UseGoogleFont = true,
    FontSize = 30,
    IsBold = true,
    IsItalic = true,
    VerticalAlignment = VerticalAlignment.Top,
};

// Stamp the text stamper
pdf.ApplyStamp(textStamper);
pdf.SaveAs("stampText.pdf");

// Create image stamper
ImageStamper imageStamper = new ImageStamper(new Uri("https://ironpdf.com/img/svgs/iron-pdf-logo.svg"))
{
    VerticalAlignment = VerticalAlignment.Top,
};

// Stamp the image stamper
pdf.ApplyStamp(imageStamper, 0);
pdf.SaveAs("stampImage.pdf");

Imports IronPdf
Imports IronPdf.Editing

Private renderer As New ChromePdfRenderer()

Private pdf As PdfDocument = renderer.RenderHtmlAsPdf("<h1>Example HTML Document!</h1>")

' Create text stamper
Private textStamper As New TextStamper() With {
	.Text = "Text Stamper!",
	.FontFamily = "Bungee Spice",
	.UseGoogleFont = True,
	.FontSize = 30,
	.IsBold = True,
	.IsItalic = True,
	.VerticalAlignment = VerticalAlignment.Top
}

' Stamp the text stamper
pdf.ApplyStamp(textStamper)
pdf.SaveAs("stampText.pdf")

' Create image stamper
Dim imageStamper As New ImageStamper(New Uri("https://ironpdf.com/img/svgs/iron-pdf-logo.svg")) With {.VerticalAlignment = VerticalAlignment.Top}

' Stamp the image stamper
pdf.ApplyStamp(imageStamper, 0)
pdf.SaveAs("stampImage.pdf")

VB C#

iTextSharp

using iText.Kernel.Pdf;
using iText.Layout;
using iText.Layout.Element;

public void StampPDF(string inputPdfPath, string outputPdfPath, string stampText)
{
    PdfDocument pdfDoc = new PdfDocument(new PdfReader(inputPdfPath), new PdfWriter(outputPdfPath));

    var document = new Document(pdfDoc);

    // Add stamp (text) to each page
    int numPages = pdfDoc.GetNumberOfPages();
    for (int i = 1; i <= numPages; i++)
    {
        doc.ShowTextAligned(new Paragraph(stampText),
                            36, 36, i, iText.Layout.Properties.TextAlignment.LEFT,
                            iText.Layout.Properties.VerticalAlignment.TOP, 0);
    }

    doc.Close();
}

using iText.Kernel.Pdf;
using iText.Layout;
using iText.Layout.Element;

public void StampPDF(string inputPdfPath, string outputPdfPath, string stampText)
{
    PdfDocument pdfDoc = new PdfDocument(new PdfReader(inputPdfPath), new PdfWriter(outputPdfPath));

    var document = new Document(pdfDoc);

    // Add stamp (text) to each page
    int numPages = pdfDoc.GetNumberOfPages();
    for (int i = 1; i <= numPages; i++)
    {
        doc.ShowTextAligned(new Paragraph(stampText),
                            36, 36, i, iText.Layout.Properties.TextAlignment.LEFT,
                            iText.Layout.Properties.VerticalAlignment.TOP, 0);
    }

    doc.Close();
}

Imports iText.Kernel.Pdf
Imports iText.Layout
Imports iText.Layout.Element

Public Sub StampPDF(ByVal inputPdfPath As String, ByVal outputPdfPath As String, ByVal stampText As String)
	Dim pdfDoc As New PdfDocument(New PdfReader(inputPdfPath), New PdfWriter(outputPdfPath))

	Dim document As New Document(pdfDoc)

	' Add stamp (text) to each page
	Dim numPages As Integer = pdfDoc.GetNumberOfPages()
	For i As Integer = 1 To numPages
		doc.ShowTextAligned(New Paragraph(stampText), 36, 36, i, iText.Layout.Properties.TextAlignment.LEFT, iText.Layout.Properties.VerticalAlignment.TOP, 0)
	Next i

	doc.Close()
End Sub

VB C#

IronPDF can help you add text or images onto PDFs in a way that’s really versatile and customizable; it lets you take complete charge. It is easy to understand and work with the API, especially for developers familiar with HTML/CSS. iTextSharp makes use of its image and text stamping tools to give users more control over the content displayed on their PDF files, although the process can end up being more manual.

Convert DOCX to PDF

Sometimes, you might have to convert PDFs from one format to the other. In this case, we looking at DOCX to PDF conversion and comparing how IronPDF and iTextSharp handle this process differently.

IronPDF

using IronPdf;

// Instantiate Renderer
DocxToPdfRenderer renderer = new DocxToPdfRenderer();

// Render from DOCX file
PdfDocument pdf = renderer.RenderDocxAsPdf("Modern-chronological-resume.docx");

// Save the PDF
pdf.SaveAs("pdfFromDocx.pdf");

using IronPdf;

// Instantiate Renderer
DocxToPdfRenderer renderer = new DocxToPdfRenderer();

// Render from DOCX file
PdfDocument pdf = renderer.RenderDocxAsPdf("Modern-chronological-resume.docx");

// Save the PDF
pdf.SaveAs("pdfFromDocx.pdf");

Imports IronPdf

' Instantiate Renderer
Private renderer As New DocxToPdfRenderer()

' Render from DOCX file
Private pdf As PdfDocument = renderer.RenderDocxAsPdf("Modern-chronological-resume.docx")

' Save the PDF
pdf.SaveAs("pdfFromDocx.pdf")

VB C#

iTextSharp

Unfortunately, iTextSharp does not provide built-in DOCX to PDF conversion functionality, and developers must rely on external libraries like Aspose.Words for this task.

IronPDF provides developers with a straightforward and concise tool for handling DOCX to PDF conversion tasks, making it easy to convert DOCX files to a PDF format with the need for external libraries. iTextSharp, on the other hand, relies on external libraries in order to carry out this task.

Summary of the Code Examples Comparison

For more detailed examples, visit IronPDF Examples.

Pricing and Licensing: IronPDF vs. iTextSharp Library

IronPDF Pricing and Licensing

IronPDF has different levels and additional features for purchasing a license. Developers can also buy IronSuite which, gives you access to all of IronSoftware’s products at the price of two. If you’re not ready to buy a license, IronPDF provides a free trial that lasts 30 days.

Perpetual licenses: Offers a range of perpetual licenses depending on the size of your team, your project needs, and the number of locations. Each license type comes with email support.
Lite License: This license costs $749 and supports one developer, one location, and one project.
Plus License: Supporting three developers, three locations, and three projects, this is the next step up from the lite license and costs $1,499. The Plus license offers chat support and phone support in addition to basic email support.
Professional License: This license is suitable for larger teams, supporting ten developers, ten locations, and ten projects for $2,999. It offers the same contact support channels as the previous tiers but also offers screen-sharing support.
Royalty-free redistribution: IronPDF's licensing also offers royalty-free redistribution coverage for an extra $1,999
Uninterrupted product support: IronPDF offers access to ongoing product updates, security feature upgrades, and support from their engineering team for either $999/year or a one-time purchase of $1,999 for a 5-year coverage.
IronSuite: For $1,498, you get access to all Iron Software products including IronPDF, IronOCR, IronWord, IronXL, IronBarcode, IronQR, IronZIP, IronPrint, and IronWebScraper.

iTextSharp Licensing

AGPL License: iTextSharp is available for free under the AGPL (Affero General Public License). This license requires that any software using iTextSharp be open-source under the same license if it is redistributed.
Commercial License: For projects that don't meet AGPL terms, iTextSharp offers a commercial license to allow its use in proprietary software. Pricing for this license is based on a quote-based model and varies depending on the usage and scope of the project.

Documentation and Support: IronPDF vs. iText

IronPDF

Comprehensive Documentation: Extensive and user-friendly documentation covering all the features it has to offer.
24/5 Support: Active engineer support is available.
Video Tutorials: Step-by-step video guides are available on YouTube.
Community Forum: Engaged community for additional support.
Regular Updates: Monthly product updates to ensure the latest features and security patches.

iTextSharp

Documentation: iTextSharp offers detailed documentation covering its key functionalities.
Examples and Tutorials: A variety of tutorials and code examples are provided to help developers get started.
GitHub: Developers can submit issues or bugs to the iTextSharp GitHub repository and interact with the iTextSharp community for support.
Updates: Regular updates are provided to improve features and address bugs.

For more details on IronPDF documentation and support, visit IronPDF Documentation and the IronSoftware YouTube Channel.

Conclusion

Both IronPDF and iTextSharp are solid options for PDF manipulation in .NET projects. IronPDF distinguishes itself with its intuitive platform integration and features like HTML-to-PDF conversion and advanced security options. iTextSharp, while rooted in the open-source iText library, offers a powerful and flexible toolset under the AGPL and commercial licenses, making it ideal for projects that can benefit from open-source flexibility or require strict licensing compliance.

Choosing the right tool depends on your project’s licensing requirements, technical support needs, and specific feature demands. Whether you favor the simplicity and comprehensive support of IronPDF or the open-source robustness of iTextSharp, both libraries offer developers ample resources to enhance PDF workflows in their applications.

You can try the 30-day free trial to check out their available features.

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