The C# PDF Library

HTML to PDF

using IronPdf;

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

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

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

// Export to a file or Stream
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 a HTML string using C#
var pdf = renderer.RenderHtmlAsPdf("<h1>Hello World</h1>");

// Export to a file or Stream
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");

PM >Install-Package IronPdf

Install-Package IronPdf

MIGRATION GUIDES

How to Migrate from Syncfusion PDF to IronPDF in C#

Curtis Chau

Updated: August 1, 2026

Migrating from Syncfusion PDF Framework to IronPDF transforms your PDF generation workflow from a coordinate-based graphics API bundled within a large suite to a standalone, HTML/CSS-first library with modern Chromium rendering. This guide provides a complete, step-by-step migration path that eliminates suite-only licensing, complex deployment requirements, and coordinate-based positioning.

Why Migrate from Syncfusion PDF to IronPDF

Understanding Syncfusion PDF Framework

The Syncfusion PDF Framework is a comprehensive library that provides a wide range of functionalities for creating, editing, and securing PDF documents using C#. It comes as a part of Syncfusion's Essential Studio, which includes over a thousand components across multiple platforms.

The PDF library cannot be purchased as a single component. Syncfusion now offers a "Document SDK" tier that bundles the PDF, Word, Excel, and PowerPoint libraries without the UI components, alongside the full Essential Studio suite. Teams that need only PDF functionality must take the Document SDK at minimum, which can be cumbersome when the other document libraries go unused.

The Bundle Licensing Problem

Syncfusion's licensing model creates significant challenges for teams that only need PDF functionality:

No Per-Library Purchase: PDF is bundled into the Document SDK (PDF + Word + Excel + PowerPoint) or full Essential Studio - it cannot be licensed on its own
Community License Restrictions: Free tier requires <$1M annual revenue, ≤5 developers, AND ≤10 total employees, plus a $3M lifetime cap on outside capital
Complex Deployment Licensing: Different licenses for web, desktop, server deployments
Annual Renewal Required: Subscription model with yearly costs (minimum 1-year term)
Per-Developer Pricing: Costs scale linearly with team size
Bundle Bloat: Document SDK pulls in Word/Excel/PowerPoint dependencies even if you only need PDF; full Essential Studio adds 1000+ UI components on top

Syncfusion PDF vs IronPDF Comparison

Aspect	Syncfusion PDF	IronPDF
Purchase Model	Document SDK bundle or full Essential Studio (no per-library SKU)	Standalone
Licensing	Complex tiers	Simple per-developer
Community Limit	<$1M revenue, ≤5 devs, ≤10 employees, ≤$3M outside capital	Free trial, then license
Deployment	Multiple license types	One license covers all
API Style	Coordinate-based graphics + HTML converter	HTML/CSS-first
HTML Engine	Blink (separate Windows/Linux/Mac NuGets)	Bundled Chromium
CSS Support	Modern (Blink) - close to Chromium parity	Full CSS3/flexbox/grid
Dependencies	Multiple packages	Single NuGet
Bundle Requirement	Yes (Document SDK or Essential Studio)	No
Focus on PDF	Broad; part of larger bundle	Narrow; PDF-focused

IronPDF provides a more focused approach by offering its PDF capabilities as a standalone product. This difference significantly impacts both cost considerations and ease of integration.

For teams adopting modern .NET, IronPDF's standalone licensing and HTML/CSS-first approach provides flexibility without bundle dependencies.

Before You Start

Prerequisites

.NET Environment: .NET Framework 4.6.2+ or .NET Core 3.1+ / .NET 5/6/7/8/9+
NuGet Access: Ability to install NuGet packages
IronPDF License: Obtain your license key from ironpdf.com

NuGet Package Changes

# Remove Syncfusion packages
dotnet remove package Syncfusion.Pdf.Net.Core
dotnet remove package Syncfusion.HtmlToPdfConverter.Net.Windows
dotnet remove package Syncfusion.Licensing

# Install IronPDF
dotnet add package IronPdf

# Remove Syncfusion packages
dotnet remove package Syncfusion.Pdf.Net.Core
dotnet remove package Syncfusion.HtmlToPdfConverter.Net.Windows
dotnet remove package Syncfusion.Licensing

# Install IronPDF
dotnet add package IronPdf

SHELL

License Configuration

Syncfusion:

// Must register before any Syncfusion calls
Syncfusion.Licensing.SyncfusionLicenseProvider.RegisterLicense("YOUR-SYNCFUSION-KEY");

// Must register before any Syncfusion calls
Syncfusion.Licensing.SyncfusionLicenseProvider.RegisterLicense("YOUR-SYNCFUSION-KEY");

' Must register before any Syncfusion calls
Syncfusion.Licensing.SyncfusionLicenseProvider.RegisterLicense("YOUR-SYNCFUSION-KEY")

' Must register before any Syncfusion calls
Syncfusion.Licensing.SyncfusionLicenseProvider.RegisterLicense("YOUR-SYNCFUSION-KEY")

IronPDF:

// One-time at startup
IronPdf.License.LicenseKey = "YOUR-LICENSE-KEY";

// One-time at startup
IronPdf.License.LicenseKey = "YOUR-LICENSE-KEY";

' One-time at startup
IronPdf.License.LicenseKey = "YOUR-LICENSE-KEY"

' One-time at startup
IronPdf.License.LicenseKey = "YOUR-LICENSE-KEY"

Complete API Reference

Namespace Changes

// Before: Syncfusion PDF
using Syncfusion.Pdf;
using Syncfusion.Pdf.Graphics;
using Syncfusion.Pdf.Parsing;
using Syncfusion.HtmlConverter;
using Syncfusion.Drawing;

// After: IronPDF
using IronPdf;
using IronPdf.Rendering;

// Before: Syncfusion PDF
using Syncfusion.Pdf;
using Syncfusion.Pdf.Graphics;
using Syncfusion.Pdf.Parsing;
using Syncfusion.HtmlConverter;
using Syncfusion.Drawing;

// After: IronPDF
using IronPdf;
using IronPdf.Rendering;

Imports IronPdf
Imports IronPdf.Rendering

Imports IronPdf
Imports IronPdf.Rendering

Core API Mappings

Syncfusion	IronPDF
`PdfDocument`	`ChromePdfRenderer`
`PdfLoadedDocument`	`PdfDocument.FromFile()`
`HtmlToPdfConverter`	`ChromePdfRenderer`
`graphics.DrawString()`	HTML text elements
`graphics.DrawImage()`	`<img>` tag
`PdfGrid`	HTML `<table>`
`PdfStandardFont`	CSS `font-family`
`PdfBrushes.Black`	CSS `color: black`
`document.Security`	`pdf.SecuritySettings`
`PdfTextExtractor`	`pdf.ExtractAllText()`
`ImportPageRange()`	`PdfDocument.Merge()`
`document.Save(stream)`	`pdf.SaveAs(path)`
`document.Close(true)`	Not needed

Code Migration Examples

Example 1: HTML/URL to PDF Conversion

Before (Syncfusion PDF):

// NuGet: Install-Package Syncfusion.Pdf.Net.Core
using Syncfusion.HtmlConverter;
using Syncfusion.Pdf;
using System.IO;

class Program
{
    static void Main()
    {
        // Initialize HTML to PDF converter
        HtmlToPdfConverter htmlConverter = new HtmlToPdfConverter();
        
        // Convert URL to PDF
        PdfDocument document = htmlConverter.Convert("https://www.example.com");
        
        // Save the document
        FileStream fileStream = new FileStream("Output.pdf", FileMode.Create);
        document.Save(fileStream);
        document.Close(true);
        fileStream.Close();
    }
}

// NuGet: Install-Package Syncfusion.Pdf.Net.Core
using Syncfusion.HtmlConverter;
using Syncfusion.Pdf;
using System.IO;

class Program
{
    static void Main()
    {
        // Initialize HTML to PDF converter
        HtmlToPdfConverter htmlConverter = new HtmlToPdfConverter();
        
        // Convert URL to PDF
        PdfDocument document = htmlConverter.Convert("https://www.example.com");
        
        // Save the document
        FileStream fileStream = new FileStream("Output.pdf", FileMode.Create);
        document.Save(fileStream);
        document.Close(true);
        fileStream.Close();
    }
}

' NuGet: Install-Package Syncfusion.Pdf.Net.Core
Imports Syncfusion.HtmlConverter
Imports Syncfusion.Pdf
Imports System.IO

Module Program
    Sub Main()
        ' Initialize HTML to PDF converter
        Dim htmlConverter As New HtmlToPdfConverter()
        
        ' Convert URL to PDF
        Dim document As PdfDocument = htmlConverter.Convert("https://www.example.com")
        
        ' Save the document
        Dim fileStream As New FileStream("Output.pdf", FileMode.Create)
        document.Save(fileStream)
        document.Close(True)
        fileStream.Close()
    End Sub
End Module

' NuGet: Install-Package Syncfusion.Pdf.Net.Core
Imports Syncfusion.HtmlConverter
Imports Syncfusion.Pdf
Imports System.IO

Module Program
    Sub Main()
        ' Initialize HTML to PDF converter
        Dim htmlConverter As New HtmlToPdfConverter()
        
        ' Convert URL to PDF
        Dim document As PdfDocument = htmlConverter.Convert("https://www.example.com")
        
        ' Save the document
        Dim fileStream As New FileStream("Output.pdf", FileMode.Create)
        document.Save(fileStream)
        document.Close(True)
        fileStream.Close()
    End Sub
End Module

After (IronPDF):

// NuGet: Install-Package IronPdf
using IronPdf;

class Program
{
    static void Main()
    {
        // Create a PDF from a URL
        var renderer = new ChromePdfRenderer();
        var pdf = renderer.RenderUrlAsPdf("https://www.example.com");
        
        // Save the PDF
        pdf.SaveAs("Output.pdf");
    }
}

// NuGet: Install-Package IronPdf
using IronPdf;

class Program
{
    static void Main()
    {
        // Create a PDF from a URL
        var renderer = new ChromePdfRenderer();
        var pdf = renderer.RenderUrlAsPdf("https://www.example.com");
        
        // Save the PDF
        pdf.SaveAs("Output.pdf");
    }
}

' NuGet: Install-Package IronPdf
Imports IronPdf

Module Program
    Sub Main()
        ' Create a PDF from a URL
        Dim renderer As New ChromePdfRenderer()
        Dim pdf = renderer.RenderUrlAsPdf("https://www.example.com")
        
        ' Save the PDF
        pdf.SaveAs("Output.pdf")
    End Sub
End Module

' NuGet: Install-Package IronPdf
Imports IronPdf

Module Program
    Sub Main()
        ' Create a PDF from a URL
        Dim renderer As New ChromePdfRenderer()
        Dim pdf = renderer.RenderUrlAsPdf("https://www.example.com")
        
        ' Save the PDF
        pdf.SaveAs("Output.pdf")
    End Sub
End Module

This example demonstrates the fundamental API differences. Syncfusion PDF requires an HtmlToPdfConverter instance, calling Convert() which returns a PdfDocument, then manually creating a FileStream, saving, and closing both the document and stream.

IronPDF uses a ChromePdfRenderer with RenderUrlAsPdf() in just three lines of code. No FileStream management, no Close() calls - IronPDF handles cleanup automatically. See the HTML to PDF documentation for comprehensive examples.

Example 2: Creating PDF from Text

Before (Syncfusion PDF):

// NuGet: Install-Package Syncfusion.Pdf.Net.Core
using Syncfusion.Pdf;
using Syncfusion.Pdf.Graphics;
using Syncfusion.Drawing;
using System.IO;

class Program
{
    static void Main()
    {
        // Create a new PDF document
        PdfDocument document = new PdfDocument();
        
        // Add a page
        PdfPage page = document.Pages.Add();
        
        // Create a font
        PdfFont font = new PdfStandardFont(PdfFontFamily.Helvetica, 12);
        
        // Draw text
        page.Graphics.DrawString("Hello, World!", font, PdfBrushes.Black, new PointF(10, 10));
        
        // Save the document
        FileStream fileStream = new FileStream("Output.pdf", FileMode.Create);
        document.Save(fileStream);
        document.Close(true);
        fileStream.Close();
    }
}

// NuGet: Install-Package Syncfusion.Pdf.Net.Core
using Syncfusion.Pdf;
using Syncfusion.Pdf.Graphics;
using Syncfusion.Drawing;
using System.IO;

class Program
{
    static void Main()
    {
        // Create a new PDF document
        PdfDocument document = new PdfDocument();
        
        // Add a page
        PdfPage page = document.Pages.Add();
        
        // Create a font
        PdfFont font = new PdfStandardFont(PdfFontFamily.Helvetica, 12);
        
        // Draw text
        page.Graphics.DrawString("Hello, World!", font, PdfBrushes.Black, new PointF(10, 10));
        
        // Save the document
        FileStream fileStream = new FileStream("Output.pdf", FileMode.Create);
        document.Save(fileStream);
        document.Close(true);
        fileStream.Close();
    }
}

' NuGet: Install-Package Syncfusion.Pdf.Net.Core
Imports Syncfusion.Pdf
Imports Syncfusion.Pdf.Graphics
Imports Syncfusion.Drawing
Imports System.IO

Module Program
    Sub Main()
        ' Create a new PDF document
        Dim document As New PdfDocument()
        
        ' Add a page
        Dim page As PdfPage = document.Pages.Add()
        
        ' Create a font
        Dim font As PdfFont = New PdfStandardFont(PdfFontFamily.Helvetica, 12)
        
        ' Draw text
        page.Graphics.DrawString("Hello, World!", font, PdfBrushes.Black, New PointF(10, 10))
        
        ' Save the document
        Dim fileStream As New FileStream("Output.pdf", FileMode.Create)
        document.Save(fileStream)
        document.Close(True)
        fileStream.Close()
    End Sub
End Module

' NuGet: Install-Package Syncfusion.Pdf.Net.Core
Imports Syncfusion.Pdf
Imports Syncfusion.Pdf.Graphics
Imports Syncfusion.Drawing
Imports System.IO

Module Program
    Sub Main()
        ' Create a new PDF document
        Dim document As New PdfDocument()
        
        ' Add a page
        Dim page As PdfPage = document.Pages.Add()
        
        ' Create a font
        Dim font As PdfFont = New PdfStandardFont(PdfFontFamily.Helvetica, 12)
        
        ' Draw text
        page.Graphics.DrawString("Hello, World!", font, PdfBrushes.Black, New PointF(10, 10))
        
        ' Save the document
        Dim fileStream As New FileStream("Output.pdf", FileMode.Create)
        document.Save(fileStream)
        document.Close(True)
        fileStream.Close()
    End Sub
End Module

After (IronPDF):

// NuGet: Install-Package IronPdf
using IronPdf;
using IronPdf.Rendering;

class Program
{
    static void Main()
    {
        // Create a PDF from HTML string
        var renderer = new ChromePdfRenderer();
        var pdf = renderer.RenderHtmlAsPdf("<h1>Hello, World!</h1>");
        
        // Save the document
        pdf.SaveAs("Output.pdf");
    }
}

// NuGet: Install-Package IronPdf
using IronPdf;
using IronPdf.Rendering;

class Program
{
    static void Main()
    {
        // Create a PDF from HTML string
        var renderer = new ChromePdfRenderer();
        var pdf = renderer.RenderHtmlAsPdf("<h1>Hello, World!</h1>");
        
        // Save the document
        pdf.SaveAs("Output.pdf");
    }
}

' NuGet: Install-Package IronPdf
Imports IronPdf
Imports IronPdf.Rendering

Module Program
    Sub Main()
        ' Create a PDF from HTML string
        Dim renderer As New ChromePdfRenderer()
        Dim pdf = renderer.RenderHtmlAsPdf("<h1>Hello, World!</h1>")
        
        ' Save the document
        pdf.SaveAs("Output.pdf")
    End Sub
End Module

' NuGet: Install-Package IronPdf
Imports IronPdf
Imports IronPdf.Rendering

Module Program
    Sub Main()
        ' Create a PDF from HTML string
        Dim renderer As New ChromePdfRenderer()
        Dim pdf = renderer.RenderHtmlAsPdf("<h1>Hello, World!</h1>")
        
        ' Save the document
        pdf.SaveAs("Output.pdf")
    End Sub
End Module

Syncfusion PDF uses a coordinate-based graphics model. You create a PdfDocument, add a PdfPage, create a PdfFont with PdfFontFamily.Helvetica, then call page.Graphics.DrawString() with explicit coordinates (new PointF(10, 10)), font, and brush (PdfBrushes.Black). Finally, you manage FileStream creation and disposal.

IronPDF uses an HTML/CSS-first approach. Instead of coordinates, you write <h1>Hello, World!</h1> and let CSS handle positioning, fonts, and colors. This approach is simpler, more maintainable, and leverages skills developers already have. Learn more in our tutorials.

Example 3: Merging PDF Documents

Before (Syncfusion PDF):

// NuGet: Install-Package Syncfusion.Pdf.Net.Core
using Syncfusion.Pdf;
using Syncfusion.Pdf.Parsing;
using System.IO;

class Program
{
    static void Main()
    {
        // Load the first PDF document
        FileStream stream1 = new FileStream("Document1.pdf", FileMode.Open, FileAccess.Read);
        PdfLoadedDocument loadedDocument1 = new PdfLoadedDocument(stream1);
        
        // Load the second PDF document
        FileStream stream2 = new FileStream("Document2.pdf", FileMode.Open, FileAccess.Read);
        PdfLoadedDocument loadedDocument2 = new PdfLoadedDocument(stream2);
        
        // Merge the documents
        PdfDocument finalDocument = new PdfDocument();
        finalDocument.ImportPageRange(loadedDocument1, 0, loadedDocument1.Pages.Count - 1);
        finalDocument.ImportPageRange(loadedDocument2, 0, loadedDocument2.Pages.Count - 1);
        
        // Save the merged document
        FileStream outputStream = new FileStream("Merged.pdf", FileMode.Create);
        finalDocument.Save(outputStream);
        
        // Close all documents
        finalDocument.Close(true);
        loadedDocument1.Close(true);
        loadedDocument2.Close(true);
        stream1.Close();
        stream2.Close();
        outputStream.Close();
    }
}

// NuGet: Install-Package Syncfusion.Pdf.Net.Core
using Syncfusion.Pdf;
using Syncfusion.Pdf.Parsing;
using System.IO;

class Program
{
    static void Main()
    {
        // Load the first PDF document
        FileStream stream1 = new FileStream("Document1.pdf", FileMode.Open, FileAccess.Read);
        PdfLoadedDocument loadedDocument1 = new PdfLoadedDocument(stream1);
        
        // Load the second PDF document
        FileStream stream2 = new FileStream("Document2.pdf", FileMode.Open, FileAccess.Read);
        PdfLoadedDocument loadedDocument2 = new PdfLoadedDocument(stream2);
        
        // Merge the documents
        PdfDocument finalDocument = new PdfDocument();
        finalDocument.ImportPageRange(loadedDocument1, 0, loadedDocument1.Pages.Count - 1);
        finalDocument.ImportPageRange(loadedDocument2, 0, loadedDocument2.Pages.Count - 1);
        
        // Save the merged document
        FileStream outputStream = new FileStream("Merged.pdf", FileMode.Create);
        finalDocument.Save(outputStream);
        
        // Close all documents
        finalDocument.Close(true);
        loadedDocument1.Close(true);
        loadedDocument2.Close(true);
        stream1.Close();
        stream2.Close();
        outputStream.Close();
    }
}

' NuGet: Install-Package Syncfusion.Pdf.Net.Core
Imports Syncfusion.Pdf
Imports Syncfusion.Pdf.Parsing
Imports System.IO

Module Program
    Sub Main()
        ' Load the first PDF document
        Dim stream1 As FileStream = New FileStream("Document1.pdf", FileMode.Open, FileAccess.Read)
        Dim loadedDocument1 As PdfLoadedDocument = New PdfLoadedDocument(stream1)
        
        ' Load the second PDF document
        Dim stream2 As FileStream = New FileStream("Document2.pdf", FileMode.Open, FileAccess.Read)
        Dim loadedDocument2 As PdfLoadedDocument = New PdfLoadedDocument(stream2)
        
        ' Merge the documents
        Dim finalDocument As PdfDocument = New PdfDocument()
        finalDocument.ImportPageRange(loadedDocument1, 0, loadedDocument1.Pages.Count - 1)
        finalDocument.ImportPageRange(loadedDocument2, 0, loadedDocument2.Pages.Count - 1)
        
        ' Save the merged document
        Dim outputStream As FileStream = New FileStream("Merged.pdf", FileMode.Create)
        finalDocument.Save(outputStream)
        
        ' Close all documents
        finalDocument.Close(True)
        loadedDocument1.Close(True)
        loadedDocument2.Close(True)
        stream1.Close()
        stream2.Close()
        outputStream.Close()
    End Sub
End Module

' NuGet: Install-Package Syncfusion.Pdf.Net.Core
Imports Syncfusion.Pdf
Imports Syncfusion.Pdf.Parsing
Imports System.IO

Module Program
    Sub Main()
        ' Load the first PDF document
        Dim stream1 As FileStream = New FileStream("Document1.pdf", FileMode.Open, FileAccess.Read)
        Dim loadedDocument1 As PdfLoadedDocument = New PdfLoadedDocument(stream1)
        
        ' Load the second PDF document
        Dim stream2 As FileStream = New FileStream("Document2.pdf", FileMode.Open, FileAccess.Read)
        Dim loadedDocument2 As PdfLoadedDocument = New PdfLoadedDocument(stream2)
        
        ' Merge the documents
        Dim finalDocument As PdfDocument = New PdfDocument()
        finalDocument.ImportPageRange(loadedDocument1, 0, loadedDocument1.Pages.Count - 1)
        finalDocument.ImportPageRange(loadedDocument2, 0, loadedDocument2.Pages.Count - 1)
        
        ' Save the merged document
        Dim outputStream As FileStream = New FileStream("Merged.pdf", FileMode.Create)
        finalDocument.Save(outputStream)
        
        ' Close all documents
        finalDocument.Close(True)
        loadedDocument1.Close(True)
        loadedDocument2.Close(True)
        stream1.Close()
        stream2.Close()
        outputStream.Close()
    End Sub
End Module

After (IronPDF):

// NuGet: Install-Package IronPdf
using IronPdf;
using System.Collections.Generic;

class Program
{
    static void Main()
    {
        // Load PDF documents
        var pdf1 = PdfDocument.FromFile("Document1.pdf");
        var pdf2 = PdfDocument.FromFile("Document2.pdf");
        
        // Merge PDFs
        var merged = PdfDocument.Merge(new List<PdfDocument> { pdf1, pdf2 });
        
        // Save the merged document
        merged.SaveAs("Merged.pdf");
    }
}

// NuGet: Install-Package IronPdf
using IronPdf;
using System.Collections.Generic;

class Program
{
    static void Main()
    {
        // Load PDF documents
        var pdf1 = PdfDocument.FromFile("Document1.pdf");
        var pdf2 = PdfDocument.FromFile("Document2.pdf");
        
        // Merge PDFs
        var merged = PdfDocument.Merge(new List<PdfDocument> { pdf1, pdf2 });
        
        // Save the merged document
        merged.SaveAs("Merged.pdf");
    }
}

' NuGet: Install-Package IronPdf
Imports IronPdf
Imports System.Collections.Generic

Class Program
    Shared Sub Main()
        ' Load PDF documents
        Dim pdf1 = PdfDocument.FromFile("Document1.pdf")
        Dim pdf2 = PdfDocument.FromFile("Document2.pdf")
        
        ' Merge PDFs
        Dim merged = PdfDocument.Merge(New List(Of PdfDocument) From {pdf1, pdf2})
        
        ' Save the merged document
        merged.SaveAs("Merged.pdf")
    End Sub
End Class

' NuGet: Install-Package IronPdf
Imports IronPdf
Imports System.Collections.Generic

Class Program
    Shared Sub Main()
        ' Load PDF documents
        Dim pdf1 = PdfDocument.FromFile("Document1.pdf")
        Dim pdf2 = PdfDocument.FromFile("Document2.pdf")
        
        ' Merge PDFs
        Dim merged = PdfDocument.Merge(New List(Of PdfDocument) From {pdf1, pdf2})
        
        ' Save the merged document
        merged.SaveAs("Merged.pdf")
    End Sub
End Class

The contrast in merging PDFs is dramatic. Syncfusion PDF requires creating FileStream objects for each input document, loading them as PdfLoadedDocument, creating a new PdfDocument, calling ImportPageRange() with start and end indices for each source, creating an output FileStream, and then closing six separate objects (finalDocument, loadedDocument1, loadedDocument2, stream1, stream2, outputStream).

IronPDF uses PdfDocument.FromFile() to load each PDF and a static PdfDocument.Merge() method that accepts a list of documents. No stream management, no manual page range calculations, no close calls.

Key Differences in API Philosophy

Coordinate-Based vs HTML/CSS-First

Syncfusion PDF uses a coordinate-based graphics model inherited from traditional PDF libraries:

// Syncfusion: Manual positioning
page.Graphics.DrawString("Text", font, PdfBrushes.Black, new PointF(100, 200));
page.Graphics.DrawRectangle(brush, new RectangleF(50, 50, 200, 100));

// Syncfusion: Manual positioning
page.Graphics.DrawString("Text", font, PdfBrushes.Black, new PointF(100, 200));
page.Graphics.DrawRectangle(brush, new RectangleF(50, 50, 200, 100));

' Syncfusion: Manual positioning
page.Graphics.DrawString("Text", font, PdfBrushes.Black, New PointF(100, 200))
page.Graphics.DrawRectangle(brush, New RectangleF(50, 50, 200, 100))

' Syncfusion: Manual positioning
page.Graphics.DrawString("Text", font, PdfBrushes.Black, New PointF(100, 200))
page.Graphics.DrawRectangle(brush, New RectangleF(50, 50, 200, 100))

IronPDF uses HTML/CSS for layout:

// IronPDF: CSS-based positioning
var html = @"
<div style='margin: 50px; padding: 20px; border: 1px solid black;'>
    <p style='color: black;'>Text</p>
</div>";
var pdf = renderer.RenderHtmlAsPdf(html);

// IronPDF: CSS-based positioning
var html = @"
<div style='margin: 50px; padding: 20px; border: 1px solid black;'>
    <p style='color: black;'>Text</p>
</div>";
var pdf = renderer.RenderHtmlAsPdf(html);

' IronPDF: CSS-based positioning
Dim html As String = "
<div style='margin: 50px; padding: 20px; border: 1px solid black;'>
    <p style='color: black;'>Text</p>
</div>"
Dim pdf = renderer.RenderHtmlAsPdf(html)

' IronPDF: CSS-based positioning
Dim html As String = "
<div style='margin: 50px; padding: 20px; border: 1px solid black;'>
    <p style='color: black;'>Text</p>
</div>"
Dim pdf = renderer.RenderHtmlAsPdf(html)

The HTML/CSS approach is more intuitive for web developers, easier to maintain, and produces consistent results across different page sizes.

Stream Management vs Automatic Cleanup

Syncfusion PDF requires explicit stream and document disposal:

// Syncfusion: Manual cleanup
FileStream fileStream = new FileStream("Output.pdf", FileMode.Create);
document.Save(fileStream);
document.Close(true);
fileStream.Close();

// Syncfusion: Manual cleanup
FileStream fileStream = new FileStream("Output.pdf", FileMode.Create);
document.Save(fileStream);
document.Close(true);
fileStream.Close();

' Syncfusion: Manual cleanup
Dim fileStream As New FileStream("Output.pdf", FileMode.Create)
document.Save(fileStream)
document.Close(True)
fileStream.Close()

' Syncfusion: Manual cleanup
Dim fileStream As New FileStream("Output.pdf", FileMode.Create)
document.Save(fileStream)
document.Close(True)
fileStream.Close()

IronPDF handles cleanup automatically:

// IronPDF: Automatic cleanup
pdf.SaveAs("Output.pdf");

// IronPDF: Automatic cleanup
pdf.SaveAs("Output.pdf");

' IronPDF: Automatic cleanup
pdf.SaveAs("Output.pdf")

' IronPDF: Automatic cleanup
pdf.SaveAs("Output.pdf")

Feature Comparison

Feature	Syncfusion PDF	IronPDF
Standalone Purchase	No (Document SDK or Essential Studio)	Yes
Licensing	Commercial with community restrictions	Simplified commercial
HTML Engine	Blink (platform-specific NuGets)	Bundled Chromium
CSS3 Support	Modern via Blink	Full (flexbox, grid)
API Style	Coordinate-based graphics + HTML converter	HTML/CSS-first
Stream Management	Manual	Automatic
Dependencies	Multiple packages	Single NuGet
Deployment Complexity	Potentially complex	Straightforward

Migration Checklist

Pre-Migration

Inventory all Syncfusion PDF usages in codebase
Document licensing costs and deployment requirements
Identify PdfGrid, PdfGraphics, and HtmlToPdfConverter usages
Obtain IronPDF license key from ironpdf.com

Code Updates

Remove Syncfusion packages (Syncfusion.Pdf.Net.Core, Syncfusion.HtmlToPdfConverter.Net.Windows, Syncfusion.Licensing)
Install IronPdf NuGet package
Update namespace imports (using Syncfusion.Pdf; → using IronPdf;)
Replace Syncfusion.Licensing.SyncfusionLicenseProvider.RegisterLicense() with IronPdf.License.LicenseKey = "..."
Replace HtmlToPdfConverter.Convert() with ChromePdfRenderer.RenderUrlAsPdf() or RenderHtmlAsPdf()
Replace PdfDocument + Pages.Add() + Graphics.DrawString() with ChromePdfRenderer.RenderHtmlAsPdf()
Replace PdfLoadedDocument with PdfDocument.FromFile()
Replace ImportPageRange() with PdfDocument.Merge()
Replace document.Save(stream) with pdf.SaveAs(path)
Remove all document.Close(true) and stream.Close() calls
Replace PdfGrid with HTML <table> elements
Replace PdfStandardFont with CSS font-family
Replace PdfBrushes with CSS color properties

Testing

Visual comparison of PDF output
Verify CSS rendering improvements (flexbox, grid now work)
Test text extraction
Test merging and splitting
Performance comparison

Please note: Syncfusion is a registered trademark of its respective owner. This site is not affiliated with, endorsed by, or sponsored by Syncfusion. All product names, logos, and brands are property of their respective owners. Comparisons are for informational purposes only and reflect publicly available information at the time of writing.

Curtis Chau

Chat with engineering team now

Technical Writer

Curtis Chau holds a Bachelor’s degree in Computer Science (Carleton University) and specializes in front-end development with expertise in Node.js, TypeScript, JavaScript, and React. Passionate about crafting intuitive and aesthetically pleasing user interfaces, Curtis enjoys working with modern frameworks and creating well-structured, visually appealing manuals.

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