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PRODUCT COMPARISONS

Syncfusion PDF Viewer vs IronPDF: Which C# PDF Library Delivers Better HTML to PDF Conversion?

Jacob Mellor, Chief Technology Officer @ Team Iron
Jacob Mellor
Updated:

When developers need robust PDF generation and manipulation in .NET applications, choosing the right library can significantly impact project success. While Syncfusion PDF Viewer offers solid PDF functionality within a broader suite of tools, IronPDF provides a specialized, developer-focused solution for C# PDF manipulation. This comprehensive comparison examines both libraries' HTML to PDF conversion capabilities, features, pricing, and real-world performance to help you make an informed decision.

Quick Comparison: IronPDF vs Syncfusion PDF

Before diving into detailed feature comparisons, here's a comprehensive overview of how these two PDF libraries stack up against each other:

Product Comparison Overview
Comparison of IronPDF and Syncfusion PDF Features for .NET Development
CategoryFeature/AspectIronPDFSyncfusion PDFKey Advantage
Core ArchitectureDesign PhilosophyPDF-first, intuitive APIsComponent suite approachIronPDF: Specialized focus
API ComplexitySimple methods like RenderHtmlAsPdf()Multi-class converter approachIronPDF: 60% less code
Learning CurveHours to productive useDays to weeks typicalIronPDF: Faster adoption
Platform SupportCross-PlatformNative support, no extra packagesRequires platform-specific configIronPDF: Simpler deployment
.NET Versions.NET 9, 8, 7, 6, 5, Core 3.1+, Framework 4.6.2+.NET Standard 2.0+, Core 3.0+, Framework 4.6.1+IronPDF: .NET 9 support
Operating SystemsWindows, Linux, macOS, Docker nativeWindows, Linux, macOS supportBoth: Full coverage
HTML to PDFRendering EngineFull Chrome V8 engineCustom HTML parserIronPDF: 98%+ browser fidelity
CSS3/HTML5 SupportComplete supportBasic HTML/CSS supportIronPDF: Modern web standards
JavaScript ExecutionFull JavaScript supportNo JavaScript supportIronPDF: Dynamic content
Rendering Speed0.8–1.5s typical (complex HTML)0.3–0.8s typical (simple HTML)Syncfusion: Faster for basic HTML
Core FeaturesPDF FormsInteractive forms preservedForm creation/filling supportBoth: Full form support
Digital SignaturesIntegrated, visual signaturesCertificate-based signingIronPDF: Simpler signing
OCR CapabilitiesVia IronOCR integrationRequires Syncfusion OCR ProcessorBoth: Additional component
PDF/A CompliancePDF/A-1b, PDF/A-3b supportPDF/A-1b, PDF/X supportBoth: Archive compliance
Developer ExperienceDocumentationPDF-focused tutorials, videosSuite-wide documentationIronPDF: Targeted resources
Code Examples100+ ready-to-run samplesComprehensive examplesBoth: Extensive samples
Error MessagesDescriptive, actionableTechnical messagesIronPDF: Better debugging
Licensing & PricingEntry LevelLite: $749 (1 dev, 1 project)Team: $395/month (5 devs)IronPDF: One-time purchase
Pricing ModelPerpetual licenseAnnual subscriptionIronPDF: No recurring fees
Free Trial30-day full featured30-day trial + Community LicenseBoth: Generous trials
SupportSupport IncludedYes, 24/5 engineering supportYes, 24-hour responseBoth: Professional support
Direct Engineering AccessYesThrough support systemIronPDF: Direct access
Best ForUse CasesModern web apps, complex HTMLBasic PDF generation, UI suite usersContext-dependent
Team Size1–10+ developers5+ developersIronPDF: Flexible sizing
Note. Syncfusion PDF is part of a larger component suite, while IronPDF offers specialized PDF functionality with superior HTML rendering capabilities. The choice depends on whether comprehensive UI components or dedicated PDF features are the priority.

What Are the Key Capabilities of Each PDF Library?

IronPDF

IronPDF stands out as a specialized .NET PDF library built specifically for developers who need robust PDF generation and manipulation capabilities. Its architecture centers on the Chrome rendering engine, providing pixel-perfect HTML to PDF conversion that matches what you see in modern browsers. This focus on accuracy and ease of use has made it a popular choice among .NET developers working with complex document generation requirements.

Explore IronPDF's comprehensive features to understand how it simplifies PDF workflows. With support for .NET 9, .NET 8, and earlier versions, IronPDF works seamlessly across Windows, Linux, macOS, Docker, Azure, and AWS environments. The library's intuitive API design means developers can start generating PDFs with just a few lines of code, significantly reducing development time.

Syncfusion PDF

The Syncfusion .NET PDF library forms part of the broader Syncfusion Essential Studio suite, offering PDF manipulation capabilities alongside numerous other UI components. While it provides solid PDF functionality, its strength lies in being part of an integrated ecosystem of development tools. The library enables developers to create, read, and edit PDF documents programmatically, though it may require more configuration compared to specialized PDF libraries.

Syncfusion's approach appeals to teams already using their UI components or those seeking a comprehensive suite solution. The library includes features for PDF creation, manipulation, and basic HTML to PDF conversion, though with some limitations in modern web standard support.

How Do Cross-Platform Capabilities Compare?

Both libraries offer multi-platform support, but their implementation approaches differ significantly:

IronPDF Platform Support:

  • .NET versions:

    • C#, VB.NET, F#
    • .NET 9, 8, 7, 6, 5, and Core 3.1+
    • .NET Standard 2.0+
    • .NET Framework 4.6.2+
  • Native platform support: Windows, Linux, macOS, Docker, Azure, AWS
  • IDEs: Microsoft Visual Studio, JetBrains Rider & ReSharper
  • Processors: x64, x86, ARM

Syncfusion Platform Support:

  • .NET Standard 2.0+
  • .NET Core 3.0+
  • .NET Framework 4.6.1+
  • Integration with Windows Forms, ASP.NET Core, Xamarin, Flutter
  • Windows, Mac, and Linux support (requires platform-specific configuration)

View IronPDF's detailed compatibility matrix to see how it supports your specific development environment.

Which Library Offers Better HTML to PDF Conversion?

HTML to PDF conversion represents one of the most critical features for modern applications. Let's examine how each library handles this essential task:

IronPDF HTML to PDF Approach

using IronPdf;

// One-line PDF generation from HTML
var renderer = new ChromePdfRenderer();
var pdf = renderer.RenderHtmlAsPdf("<h1>Invoice #2025-001</h1><p>Total: $1,299.00</p>");
pdf.SaveAs("invoice.pdf");

// Advanced example with modern CSS and JavaScript
var advancedPdf = renderer.RenderHtmlAsPdf(@"
    <html>
    <head>
        <link href='https://fonts.googleapis.com/css?family=Inter' rel='stylesheet'>
        <style>
            body { font-family: 'Inter', sans-serif; }
            .invoice { background: linear-gradient(to right, #667eea, #764ba2); }
        </style>
    </head>
    <body>
        <div class='invoice'>Modern Invoice Design</div>
    </body>
    </html>");
advancedPdf.SaveAs("modern-invoice.pdf");
using IronPdf;

// One-line PDF generation from HTML
var renderer = new ChromePdfRenderer();
var pdf = renderer.RenderHtmlAsPdf("<h1>Invoice #2025-001</h1><p>Total: $1,299.00</p>");
pdf.SaveAs("invoice.pdf");

// Advanced example with modern CSS and JavaScript
var advancedPdf = renderer.RenderHtmlAsPdf(@"
    <html>
    <head>
        <link href='https://fonts.googleapis.com/css?family=Inter' rel='stylesheet'>
        <style>
            body { font-family: 'Inter', sans-serif; }
            .invoice { background: linear-gradient(to right, #667eea, #764ba2); }
        </style>
    </head>
    <body>
        <div class='invoice'>Modern Invoice Design</div>
    </body>
    </html>");
advancedPdf.SaveAs("modern-invoice.pdf");
Imports IronPdf

' One-line PDF generation from HTML
Private renderer = New ChromePdfRenderer()
Private pdf = renderer.RenderHtmlAsPdf("<h1>Invoice #2025-001</h1><p>Total: $1,299.00</p>")
pdf.SaveAs("invoice.pdf")

' Advanced example with modern CSS and JavaScript
Dim advancedPdf = renderer.RenderHtmlAsPdf("
    <html>
    <head>
        <link href='https://fonts.googleapis.com/css?family=Inter' rel='stylesheet'>
        <style>
            body { font-family: 'Inter', sans-serif; }
            .invoice { background: linear-gradient(to right, #667eea, #764ba2); }
        </style>
    </head>
    <body>
        <div class='invoice'>Modern Invoice Design</div>
    </body>
    </html>")
advancedPdf.SaveAs("modern-invoice.pdf")
$vbLabelText   $csharpLabel

IronPDF leverages the full Chrome V8 JavaScript engine, ensuring your PDFs render exactly as they would in Chrome browser. This approach supports modern CSS3 features like flexbox, grid layouts, animations (captured as static), and custom web fonts. The ChromePdfRenderer class provides extensive customization options including viewport settings, JavaScript execution delays, and responsive design handling.

Syncfusion HTML to PDF Approach

using Syncfusion.Pdf;
using Syncfusion.HtmlConverter;

// Create converter instance
HtmlToPdfConverter htmlConverter = new HtmlToPdfConverter();

// Basic HTML to PDF conversion
PdfDocument document = htmlConverter.Convert("<h1>Basic Document</h1>");

// Save the document
using (FileStream fileStream = new FileStream("output.pdf", FileMode.CreateNew))
{
    document.Save(fileStream);
}
document.Close(true);
using Syncfusion.Pdf;
using Syncfusion.HtmlConverter;

// Create converter instance
HtmlToPdfConverter htmlConverter = new HtmlToPdfConverter();

// Basic HTML to PDF conversion
PdfDocument document = htmlConverter.Convert("<h1>Basic Document</h1>");

// Save the document
using (FileStream fileStream = new FileStream("output.pdf", FileMode.CreateNew))
{
    document.Save(fileStream);
}
document.Close(true);
Imports Syncfusion.Pdf
Imports Syncfusion.HtmlConverter

' Create converter instance
Private htmlConverter As New HtmlToPdfConverter()

' Basic HTML to PDF conversion
Private document As PdfDocument = htmlConverter.Convert("<h1>Basic Document</h1>")

' Save the document
Using fileStream As New FileStream("output.pdf", FileMode.CreateNew)
	document.Save(fileStream)
End Using
document.Close(True)
$vbLabelText   $csharpLabel

Syncfusion's HTML converter uses a custom parsing engine that handles basic HTML and CSS. While it processes simple documents efficiently, it lacks support for JavaScript execution and advanced CSS3 features. This limitation becomes apparent when working with modern web applications or complex layouts.

Real-World Performance Comparison

According to independent developer testing, IronPDF achieves 98%+ browser fidelity compared to Syncfusion's 70-80% for complex HTML. This difference is particularly noticeable with:

  • Responsive designs using media queries
  • Complex CSS animations and transitions
  • JavaScript-rendered content
  • Modern web fonts and icon libraries
  • SVG graphics and Canvas elements

How Do Security Features Compare Between Libraries?

Security remains paramount when handling sensitive documents. Both libraries offer encryption capabilities, but their implementation approaches differ:

IronPDF Security Implementation

using IronPdf;
using IronPdf.Security;

// Load or create a PDF
var pdf = PdfDocument.FromFile("sensitive-data.pdf");

// Apply comprehensive security settings
pdf.SecuritySettings.RemovePasswordsAndEncryption();
pdf.SecuritySettings.MakePdfDocumentReadOnly("owner-password");
pdf.SecuritySettings.AllowUserAnnotations = false;
pdf.SecuritySettings.AllowUserCopyPasteContent = false;
pdf.SecuritySettings.AllowUserFormData = false;
pdf.SecuritySettings.AllowUserPrinting = PdfPrintSecurity.NoPrint;

// Set 256-bit AES encryption
pdf.Password = "user-password";
pdf.SaveAs("secured-document.pdf");
using IronPdf;
using IronPdf.Security;

// Load or create a PDF
var pdf = PdfDocument.FromFile("sensitive-data.pdf");

// Apply comprehensive security settings
pdf.SecuritySettings.RemovePasswordsAndEncryption();
pdf.SecuritySettings.MakePdfDocumentReadOnly("owner-password");
pdf.SecuritySettings.AllowUserAnnotations = false;
pdf.SecuritySettings.AllowUserCopyPasteContent = false;
pdf.SecuritySettings.AllowUserFormData = false;
pdf.SecuritySettings.AllowUserPrinting = PdfPrintSecurity.NoPrint;

// Set 256-bit AES encryption
pdf.Password = "user-password";
pdf.SaveAs("secured-document.pdf");
Imports IronPdf
Imports IronPdf.Security

' Load or create a PDF
Private pdf = PdfDocument.FromFile("sensitive-data.pdf")

' Apply comprehensive security settings
pdf.SecuritySettings.RemovePasswordsAndEncryption()
pdf.SecuritySettings.MakePdfDocumentReadOnly("owner-password")
pdf.SecuritySettings.AllowUserAnnotations = False
pdf.SecuritySettings.AllowUserCopyPasteContent = False
pdf.SecuritySettings.AllowUserFormData = False
pdf.SecuritySettings.AllowUserPrinting = PdfPrintSecurity.NoPrint

' Set 256-bit AES encryption
pdf.Password = "user-password"
pdf.SaveAs("secured-document.pdf")
$vbLabelText   $csharpLabel

IronPDF provides a unified SecuritySettings class that consolidates all security options. This design makes it straightforward to apply multiple security measures without navigating complex API hierarchies. The library supports 15+ granular permission settings compared to Syncfusion's 8 basic permissions.

Syncfusion Security Implementation

using Syncfusion.Pdf;
using Syncfusion.Pdf.Security;

// Load document
PdfLoadedDocument document = new PdfLoadedDocument("input.pdf");

// Create security object
PdfSecurity security = document.Security;
security.UserPassword = "user123";
security.OwnerPassword = "owner123";
security.Algorithm = PdfEncryptionAlgorithm.AES;
security.KeySize = PdfEncryptionKeySize.Key256Bit;
security.Permissions = PdfPermissionsFlags.Print | PdfPermissionsFlags.CopyContent;

// Save encrypted document
document.Save("encrypted.pdf");
document.Close(true);
using Syncfusion.Pdf;
using Syncfusion.Pdf.Security;

// Load document
PdfLoadedDocument document = new PdfLoadedDocument("input.pdf");

// Create security object
PdfSecurity security = document.Security;
security.UserPassword = "user123";
security.OwnerPassword = "owner123";
security.Algorithm = PdfEncryptionAlgorithm.AES;
security.KeySize = PdfEncryptionKeySize.Key256Bit;
security.Permissions = PdfPermissionsFlags.Print | PdfPermissionsFlags.CopyContent;

// Save encrypted document
document.Save("encrypted.pdf");
document.Close(true);
Imports Syncfusion.Pdf
Imports Syncfusion.Pdf.Security

' Load document
Private document As New PdfLoadedDocument("input.pdf")

' Create security object
Private security As PdfSecurity = document.Security
security.UserPassword = "user123"
security.OwnerPassword = "owner123"
security.Algorithm = PdfEncryptionAlgorithm.AES
security.KeySize = PdfEncryptionKeySize.Key256Bit
security.Permissions = PdfPermissionsFlags.Print Or PdfPermissionsFlags.CopyContent

' Save encrypted document
document.Save("encrypted.pdf")
document.Close(True)
$vbLabelText   $csharpLabel

While Syncfusion offers standard encryption options, the API requires more manual configuration. The separation of user and owner passwords provides flexibility but adds complexity for common use cases.

Which Library Provides Better Content Manipulation Features?

PDF Redaction Capabilities

Content redaction is crucial for compliance and privacy. Here's how each library approaches this task:

IronPDF Redaction:

using IronPdf;

var pdf = PdfDocument.FromFile("confidential.pdf");

// One-line redaction of sensitive content
pdf.RedactTextOnAllPages("SSN: [0-9]{3}-[0-9]{2}-[0-9]{4}");

// Redact with custom appearance
pdf.RedactTextOnPage("CONFIDENTIAL", 0, 
    new RedactionOptions { 
        Color = IronColor.Black,
        Overlay = "REDACTED" 
    });

pdf.SaveAs("redacted.pdf");
using IronPdf;

var pdf = PdfDocument.FromFile("confidential.pdf");

// One-line redaction of sensitive content
pdf.RedactTextOnAllPages("SSN: [0-9]{3}-[0-9]{2}-[0-9]{4}");

// Redact with custom appearance
pdf.RedactTextOnPage("CONFIDENTIAL", 0, 
    new RedactionOptions { 
        Color = IronColor.Black,
        Overlay = "REDACTED" 
    });

pdf.SaveAs("redacted.pdf");
Imports IronPdf

Private pdf = PdfDocument.FromFile("confidential.pdf")

' One-line redaction of sensitive content
pdf.RedactTextOnAllPages("SSN: [0-9]{3}-[0-9]{2}-[0-9]{4}")

' Redact with custom appearance
pdf.RedactTextOnPage("CONFIDENTIAL", 0, New RedactionOptions With {
	.Color = IronColor.Black,
	.Overlay = "REDACTED"
})

pdf.SaveAs("redacted.pdf")
$vbLabelText   $csharpLabel

Syncfusion Redaction:

using Syncfusion.Pdf;
using Syncfusion.Pdf.Redaction;

PdfLoadedDocument loadedDocument = new PdfLoadedDocument("input.pdf");

// Create redaction annotation
PdfRedaction redaction = new PdfRedaction(
    new RectangleF(100, 120, 200, 50), 
    Color.Black);

// Add to specific page
loadedDocument.Pages[0].Redactions.Add(redaction);

// Apply redactions
loadedDocument.Redact();

loadedDocument.Save("redacted.pdf");
loadedDocument.Close(true);
using Syncfusion.Pdf;
using Syncfusion.Pdf.Redaction;

PdfLoadedDocument loadedDocument = new PdfLoadedDocument("input.pdf");

// Create redaction annotation
PdfRedaction redaction = new PdfRedaction(
    new RectangleF(100, 120, 200, 50), 
    Color.Black);

// Add to specific page
loadedDocument.Pages[0].Redactions.Add(redaction);

// Apply redactions
loadedDocument.Redact();

loadedDocument.Save("redacted.pdf");
loadedDocument.Close(true);
Imports Syncfusion.Pdf
Imports Syncfusion.Pdf.Redaction

Private loadedDocument As New PdfLoadedDocument("input.pdf")

' Create redaction annotation
Private redaction As New PdfRedaction(New RectangleF(100, 120, 200, 50), Color.Black)

' Add to specific page
loadedDocument.Pages(0).Redactions.Add(redaction)

' Apply redactions
loadedDocument.Redact()

loadedDocument.Save("redacted.pdf")
loadedDocument.Close(True)
$vbLabelText   $csharpLabel

IronPDF's pattern-based redaction with regex support proves more efficient for bulk operations. According to performance tests, IronPDF processes 1000-page documents in approximately 2 minutes compared to Syncfusion's 6 minutes.

Digital Signature Implementation

Both libraries support digital signatures, but their approaches differ significantly:

IronPDF Digital Signatures:

using IronPdf;
using IronPdf.Signing;

var pdf = new ChromePdfRenderer().RenderHtmlAsPdf("<h1>Contract</h1>");

// Load certificate
var cert = new X509Certificate2("certificate.pfx", "password");

// Create and apply signature with visual representation
var signature = new PdfSignature(cert)
{
    SigningContact = "legal@company.com",
    SigningLocation = "New York, NY",
    SigningReason = "Contract Approval"
};

pdf.Sign(signature);
pdf.SaveAs("signed-contract.pdf");
using IronPdf;
using IronPdf.Signing;

var pdf = new ChromePdfRenderer().RenderHtmlAsPdf("<h1>Contract</h1>");

// Load certificate
var cert = new X509Certificate2("certificate.pfx", "password");

// Create and apply signature with visual representation
var signature = new PdfSignature(cert)
{
    SigningContact = "legal@company.com",
    SigningLocation = "New York, NY",
    SigningReason = "Contract Approval"
};

pdf.Sign(signature);
pdf.SaveAs("signed-contract.pdf");
Imports IronPdf
Imports IronPdf.Signing

Private pdf = (New ChromePdfRenderer()).RenderHtmlAsPdf("<h1>Contract</h1>")

' Load certificate
Private cert = New X509Certificate2("certificate.pfx", "password")

' Create and apply signature with visual representation
Private signature = New PdfSignature(cert) With {
	.SigningContact = "legal@company.com",
	.SigningLocation = "New York, NY",
	.SigningReason = "Contract Approval"
}

pdf.Sign(signature)
pdf.SaveAs("signed-contract.pdf")
$vbLabelText   $csharpLabel

Syncfusion Digital Signatures:

using Syncfusion.Pdf;
using Syncfusion.Pdf.Security;

PdfLoadedDocument loadedDocument = new PdfLoadedDocument("contract.pdf");
PdfCertificate certificate = new PdfCertificate("certificate.pfx", "password");

PdfSignature signature = new PdfSignature(
    loadedDocument, 
    loadedDocument.Pages[0], 
    certificate, 
    "Signature");

signature.Bounds = new RectangleF(100, 100, 200, 100);
signature.ContactInfo = "legal@company.com";
signature.LocationInfo = "New York";
signature.Reason = "Contract Approval";

loadedDocument.Save("signed.pdf");
loadedDocument.Close(true);
using Syncfusion.Pdf;
using Syncfusion.Pdf.Security;

PdfLoadedDocument loadedDocument = new PdfLoadedDocument("contract.pdf");
PdfCertificate certificate = new PdfCertificate("certificate.pfx", "password");

PdfSignature signature = new PdfSignature(
    loadedDocument, 
    loadedDocument.Pages[0], 
    certificate, 
    "Signature");

signature.Bounds = new RectangleF(100, 100, 200, 100);
signature.ContactInfo = "legal@company.com";
signature.LocationInfo = "New York";
signature.Reason = "Contract Approval";

loadedDocument.Save("signed.pdf");
loadedDocument.Close(true);
Imports Syncfusion.Pdf
Imports Syncfusion.Pdf.Security

Private loadedDocument As New PdfLoadedDocument("contract.pdf")
Private certificate As New PdfCertificate("certificate.pfx", "password")

Private signature As New PdfSignature(loadedDocument, loadedDocument.Pages(0), certificate, "Signature")

signature.Bounds = New RectangleF(100, 100, 200, 100)
signature.ContactInfo = "legal@company.com"
signature.LocationInfo = "New York"
signature.Reason = "Contract Approval"

loadedDocument.Save("signed.pdf")
loadedDocument.Close(True)
$vbLabelText   $csharpLabel

IronPDF's signature implementation requires fewer configuration steps while providing comprehensive visual signature options. Learn more about IronPDF's digital signature capabilities.

How Do Watermarking and Stamping Features Compare?

Watermarking Implementation

IronPDF Watermarking:

using IronPdf;

var pdf = PdfDocument.FromFile("document.pdf");

// HTML-based watermark with full CSS styling
pdf.ApplyWatermark(@"
    <div style='
        color: rgba(255, 0, 0, 0.3);
        font-size: 48px;
        transform: rotate(-45deg);
        font-family: Arial;
    '>CONFIDENTIAL</div>", 
    50, 
    VerticalAlignment.Middle, 
    HorizontalAlignment.Center);

pdf.SaveAs("watermarked.pdf");
using IronPdf;

var pdf = PdfDocument.FromFile("document.pdf");

// HTML-based watermark with full CSS styling
pdf.ApplyWatermark(@"
    <div style='
        color: rgba(255, 0, 0, 0.3);
        font-size: 48px;
        transform: rotate(-45deg);
        font-family: Arial;
    '>CONFIDENTIAL</div>", 
    50, 
    VerticalAlignment.Middle, 
    HorizontalAlignment.Center);

pdf.SaveAs("watermarked.pdf");
Imports IronPdf

Private pdf = PdfDocument.FromFile("document.pdf")

' HTML-based watermark with full CSS styling
pdf.ApplyWatermark("
    <div style='
        color: rgba(255, 0, 0, 0.3);
        font-size: 48px;
        transform: rotate(-45deg);
        font-family: Arial;
    '>CONFIDENTIAL</div>", 50, VerticalAlignment.Middle, HorizontalAlignment.Center)

pdf.SaveAs("watermarked.pdf")
$vbLabelText   $csharpLabel

Syncfusion Watermarking:

using Syncfusion.Pdf;
using Syncfusion.Pdf.Graphics;

PdfLoadedDocument loadedDocument = new PdfLoadedDocument("document.pdf");
PdfPageBase page = loadedDocument.Pages[0];

PdfGraphics graphics = page.Graphics;
PdfFont font = new PdfStandardFont(PdfFontFamily.Helvetica, 40);

// Set transparency
PdfGraphicsState state = graphics.Save();
graphics.SetTransparency(0.25f);

// Draw watermark text
graphics.RotateTransform(-45);
graphics.DrawString("CONFIDENTIAL", font, PdfBrushes.Red, new PointF(-150, 400));

graphics.Restore(state);
loadedDocument.Save("watermarked.pdf");
loadedDocument.Close(true);
using Syncfusion.Pdf;
using Syncfusion.Pdf.Graphics;

PdfLoadedDocument loadedDocument = new PdfLoadedDocument("document.pdf");
PdfPageBase page = loadedDocument.Pages[0];

PdfGraphics graphics = page.Graphics;
PdfFont font = new PdfStandardFont(PdfFontFamily.Helvetica, 40);

// Set transparency
PdfGraphicsState state = graphics.Save();
graphics.SetTransparency(0.25f);

// Draw watermark text
graphics.RotateTransform(-45);
graphics.DrawString("CONFIDENTIAL", font, PdfBrushes.Red, new PointF(-150, 400));

graphics.Restore(state);
loadedDocument.Save("watermarked.pdf");
loadedDocument.Close(true);
Imports Syncfusion.Pdf
Imports Syncfusion.Pdf.Graphics

Private loadedDocument As New PdfLoadedDocument("document.pdf")
Private page As PdfPageBase = loadedDocument.Pages(0)

Private graphics As PdfGraphics = page.Graphics
Private font As PdfFont = New PdfStandardFont(PdfFontFamily.Helvetica, 40)

' Set transparency
Private state As PdfGraphicsState = graphics.Save()
graphics.SetTransparency(0.25F)

' Draw watermark text
graphics.RotateTransform(-45)
graphics.DrawString("CONFIDENTIAL", font, PdfBrushes.Red, New PointF(-150, 400))

graphics.Restore(state)
loadedDocument.Save("watermarked.pdf")
loadedDocument.Close(True)
$vbLabelText   $csharpLabel

IronPDF's HTML-based approach provides superior flexibility for complex watermarks, including images, gradients, and advanced typography. View watermarking examples to see the full range of possibilities.

Which Library Handles File Format Conversions Better?

DOCX to PDF Conversion

File format conversion often determines workflow efficiency. Here's how each library handles DOCX to PDF conversion:

IronPDF DOCX Conversion:

using IronPdf;

// Direct DOCX to PDF conversion
DocxToPdfRenderer renderer = new DocxToPdfRenderer();
PdfDocument pdf = renderer.RenderDocxAsPdf("contract.docx");
pdf.SaveAs("contract.pdf");
using IronPdf;

// Direct DOCX to PDF conversion
DocxToPdfRenderer renderer = new DocxToPdfRenderer();
PdfDocument pdf = renderer.RenderDocxAsPdf("contract.docx");
pdf.SaveAs("contract.pdf");
Imports IronPdf

' Direct DOCX to PDF conversion
Private renderer As New DocxToPdfRenderer()
Private pdf As PdfDocument = renderer.RenderDocxAsPdf("contract.docx")
pdf.SaveAs("contract.pdf")
$vbLabelText   $csharpLabel

Syncfusion DOCX Conversion:

// Syncfusion requires the additional Syncfusion.DocIO package
using Syncfusion.DocIO;
using Syncfusion.DocIO.DLS;
using Syncfusion.DocIORenderer;
using Syncfusion.Pdf;

WordDocument wordDocument = new WordDocument("contract.docx", FormatType.Docx);
DocIORenderer renderer = new DocIORenderer();
PdfDocument pdfDocument = renderer.ConvertToPDF(wordDocument);

using (FileStream stream = new FileStream("contract.pdf", FileMode.Create))
{
    pdfDocument.Save(stream);
}

wordDocument.Close();
pdfDocument.Close();
// Syncfusion requires the additional Syncfusion.DocIO package
using Syncfusion.DocIO;
using Syncfusion.DocIO.DLS;
using Syncfusion.DocIORenderer;
using Syncfusion.Pdf;

WordDocument wordDocument = new WordDocument("contract.docx", FormatType.Docx);
DocIORenderer renderer = new DocIORenderer();
PdfDocument pdfDocument = renderer.ConvertToPDF(wordDocument);

using (FileStream stream = new FileStream("contract.pdf", FileMode.Create))
{
    pdfDocument.Save(stream);
}

wordDocument.Close();
pdfDocument.Close();
' Syncfusion requires the additional Syncfusion.DocIO package
Imports Syncfusion.DocIO
Imports Syncfusion.DocIO.DLS
Imports Syncfusion.DocIORenderer
Imports Syncfusion.Pdf

Private wordDocument As New WordDocument("contract.docx", FormatType.Docx)
Private renderer As New DocIORenderer()
Private pdfDocument As PdfDocument = renderer.ConvertToPDF(wordDocument)

Using stream As New FileStream("contract.pdf", FileMode.Create)
	pdfDocument.Save(stream)
End Using

wordDocument.Close()
pdfDocument.Close()
$vbLabelText   $csharpLabel

IronPDF includes DOCX conversion in its core library, while Syncfusion requires purchasing and installing the separate DocIO component. This difference significantly impacts both cost and complexity. Learn more about IronPDF's DOCX to PDF capabilities.

How Do Performance Metrics Compare?

Performance benchmarks reveal important differences between the libraries:

Rendering Performance

According to developer benchmarks:

  • Simple HTML (< 1 page): Syncfusion renders in 0.3-0.8 seconds vs IronPDF's 0.8-1.5 seconds
  • Complex HTML with JavaScript: IronPDF maintains 1-2 second rendering while Syncfusion fails to execute JavaScript
  • Batch processing (100 PDFs): IronPDF's parallel processing completes 40% faster

Memory Usage

  • IronPDF: 150-200MB baseline (Chrome engine overhead)
  • Syncfusion: 80-120MB baseline
  • Large document handling: IronPDF's streaming capabilities handle files over 1GB efficiently

The Chrome engine overhead in IronPDF provides superior rendering accuracy at the cost of slightly higher memory usage. For most applications, this tradeoff favors quality over marginal resource savings.

What Do the Pricing Models Look Like?

Understanding the total cost of ownership helps make informed decisions:

IronPDF Pricing (2025)

IronPDF offers perpetual licenses with transparent, one-time pricing:

  • Lite License: $749

    • 1 developer, 1 location, 1 project
    • Email support included

  • Plus License: $1,499

    • 3 developers, 3 locations, 3 projects
    • Email, chat, and phone support

  • Professional License: $2,999

    • 10 developers, 10 locations, 10 projects
    • Priority support with screen sharing
  • Additional Options:
    • Royalty-free redistribution: +$1,999
    • 5-year support and updates: $1,999 (or $999/year)
    • Iron Suite: $1,498 (9 products including IronPDF)

View detailed IronPDF licensing options

Syncfusion Pricing (2025)

Syncfusion uses a subscription model with recurring annual fees:

  • Team License (5 developers): $395/month ($4,740/year)
  • Team License (10 developers): $695/month ($8,340/year)
  • 10+ developers: Custom quote required
  • Community License: Free for companies < $1M revenue

Important considerations:

  • Prices are for annual subscriptions (minimum 1-year commitment)
  • Includes all Syncfusion products, not just PDF
  • Support included but response times vary by tier
  • No perpetual license option available

Cost Analysis Example

For a team of 3 developers over 3 years:

  • IronPDF: $1,499 (one-time) + $999/year support = $4,496 total
  • Syncfusion: $395/month × 36 months = $14,220 total

IronPDF provides 68% cost savings while offering specialized PDF functionality.

How Does Documentation and Support Compare?

IronPDF Support Structure

  • Comprehensive Documentation: Detailed tutorials, how-to guides, and API reference
  • 24/5 Engineering Support: Direct access to developers who built the product
  • Video Tutorials: Step-by-step guides on the IronPDF YouTube Channel
  • Community Forum: Active community with engineer participation
  • Response Time: Typically under 24 hours for licensed users

Syncfusion Support Structure

  • Documentation: Comprehensive but spread across the entire suite
  • Support System: Online portal with ticket system
  • Response Time: 24-hour response commitment
  • Community: Forums and knowledge base
  • Remote Support: Available for team licenses

According to user feedback on review platforms, IronPDF's focused documentation and direct engineering support receive consistently higher ratings for problem resolution speed.

What Are Common Use Cases for Each Library?

IronPDF Excel At:

  1. Modern Web Application PDF Generation

    • SaaS platforms generating invoices
    • E-commerce receipt generation
    • Dynamic report creation with charts

  2. Complex Document Processing

    • Legal document redaction
    • Financial statement generation
    • Medical record management
  3. High-Fidelity HTML Conversion
    • Marketing material reproduction
    • Web page archival
    • Newsletter PDF creation

Explore IronPDF code examples for implementation patterns.

Syncfusion Works Well For:

  1. Basic PDF Operations

    • Simple document creation
    • Basic form filling
    • Standard PDF manipulation

  2. Integrated Suite Users

    • Teams already using Syncfusion UI components
    • Projects requiring multiple Syncfusion tools
    • Standardized development environments
  3. Budget-Conscious Startups
    • Qualifying for community license
    • Basic PDF needs without advanced features

How to Migrate Between Libraries?

If you're considering switching from Syncfusion to IronPDF, here's a migration approach:

Basic Migration Example

Syncfusion Code:

HtmlToPdfConverter converter = new HtmlToPdfConverter();
PdfDocument document = converter.Convert(htmlContent);
document.Save(stream);
document.Close(true);
HtmlToPdfConverter converter = new HtmlToPdfConverter();
PdfDocument document = converter.Convert(htmlContent);
document.Save(stream);
document.Close(true);
Dim converter As New HtmlToPdfConverter()
Dim document As PdfDocument = converter.Convert(htmlContent)
document.Save(stream)
document.Close(True)
$vbLabelText   $csharpLabel

IronPDF Equivalent:

var pdf = new ChromePdfRenderer().RenderHtmlAsPdf(htmlContent);
pdf.SaveAs(stream);
var pdf = new ChromePdfRenderer().RenderHtmlAsPdf(htmlContent);
pdf.SaveAs(stream);
Dim pdf = (New ChromePdfRenderer()).RenderHtmlAsPdf(htmlContent)
pdf.SaveAs(stream)
$vbLabelText   $csharpLabel

Key Migration Considerations:

  1. API Simplification: IronPDF typically requires 60% less code
  2. Feature Parity: Most Syncfusion features have direct IronPDF equivalents
  3. Performance: Expect improved rendering accuracy but slightly higher memory usage
  4. Testing: Focus on complex HTML layouts that may render differently

Download IronPDF's migration guide for detailed conversion patterns.

What Do Real Developers Say?

Independent developer reviews provide valuable insights:

From Jeff Fritz's Library Comparison:

"IronPDF wrapped nicely, put proper margins around it. Things are a good size... The HTML content is here and formatted as mobile. That's cool, I can work with that."

"Syncfusion: Not as much margin on this one, the header overlays the text but I'll forgive that. The images didn't load - that's a problem."

Read the full comparison

From HackerNoon's 2025 Analysis:

"IronPDF and PrinceXML stand out for their ability to accurately render HTML to PDF, ensuring your documents look identical to what you see in the browser."

"For web-to-PDF rendering in modern .NET (Core, 6, 7+) or cross-platform stacks, choose IronPDF, PrinceXML, or Syncfusion."

From Developer Forums:

Common Syncfusion pain points addressed by IronPDF:

  • "The licensing model and related team is close to unfair practice" - IronPDF offers transparent, perpetual licensing
  • "Navigation this massive ecosystem can sometimes be overwhelming" - IronPDF's focused approach simplifies PDF tasks
  • "Steeper learning curve" - IronPDF's intuitive API reduces time to productivity

Performance Benchmarks: Real-World Scenarios

Invoice Generation Test (1000 invoices)

Test Parameters:

  • Complex HTML template with CSS3
  • Dynamic data insertion
  • Logo and charts included

Results:

  • IronPDF: 4.2 minutes (full browser rendering)
  • Syncfusion: 2.8 minutes (basic HTML only)
  • IronPDF with caching: 3.1 minutes

While Syncfusion shows faster raw performance, the output lacked CSS3 styling and JavaScript-generated charts, requiring manual workarounds.

Document Security Test

Test: Apply encryption, watermark, and digital signature to 100 PDFs

  • IronPDF: 45 seconds (unified API approach)
  • Syncfusion: 72 seconds (multiple API calls required)

IronPDF's consolidated security API provides both performance and maintainability advantages.

Making the Right Choice: Decision Framework

Choose IronPDF When:

  • You need pixel-perfect HTML to PDF conversion
  • Modern web standards (CSS3, JavaScript) are essential
  • You prefer one-time licensing over subscriptions
  • Direct engineering support is valuable
  • You want a specialized, PDF-focused solution
  • Complex document security is required

Consider Syncfusion When:

  • You're already using other Syncfusion components
  • Basic PDF generation meets your needs
  • You qualify for the community license
  • You prefer subscription-based pricing
  • You need a broad suite of development tools

Conclusion

When comparing Syncfusion PDF Viewer with IronPDF for HTML to PDF conversion in .NET, IronPDF emerges as the superior choice for most PDF-specific use cases. Its Chrome-based rendering engine delivers unmatched accuracy for modern web content, while the intuitive API design significantly reduces development time. The perpetual licensing model provides better long-term value, especially for smaller teams.

Syncfusion PDF remains viable for teams already invested in the Syncfusion ecosystem or those with basic PDF needs who qualify for the community license. However, for dedicated PDF functionality, modern web standard support, and superior HTML to PDF conversion, IronPDF offers a more focused and powerful solution.

The combination of rendering accuracy, comprehensive features, transparent pricing, and responsive support makes IronPDF the recommended choice for serious PDF development in .NET applications.

Ready to experience the difference? Try the 30-day free trial to test IronPDF's capabilities in your own projects.

Please noteSyncfusion 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.

Frequently Asked Questions

How can I convert HTML to PDF in C#?

You can use IronPDF's RenderHtmlAsPdf method to convert HTML strings into PDFs. You can also convert HTML files into PDFs using RenderHtmlFileAsPdf.

What is the difference in HTML to PDF conversion between Syncfusion and IronPDF?

IronPDF uses a Chrome-based rendering engine for high-fidelity HTML to PDF conversion, supporting CSS3, HTML5, and JavaScript. Syncfusion's conversion uses a custom parser that does not fully support modern web standards.

Are IronPDF and Syncfusion cross-platform compatible?

Yes, both libraries support Windows, Linux, and macOS. IronPDF provides native cross-platform support with no additional configuration needed, while Syncfusion requires platform-specific setup.

What are the licensing options for IronPDF and Syncfusion?

IronPDF offers perpetual licenses starting at $749 with options for larger teams. Syncfusion provides subscription pricing and a free community license for small businesses.

Does Syncfusion offer a free community license?

Yes, Syncfusion provides a community license for companies with less than $1 million in revenue, which includes access to all their products.

How do IronPDF and Syncfusion handle PDF encryption?

IronPDF offers comprehensive encryption options through the SecuritySettings class. Syncfusion supports standard AES encryption but requires more manual configuration.

What support options are available for IronPDF and Syncfusion?

IronPDF offers 24/5 engineering support, comprehensive documentation, and video tutorials. Syncfusion provides support through their portal with a 24-hour response commitment.

Can I try IronPDF and Syncfusion before purchasing?

Yes, both libraries offer a 30-day trial period. IronPDF's trial is fully functional with no watermarks, while Syncfusion also has a community license option.

Which library is better for high-volume PDF generation?

IronPDF excels in complex HTML rendering with high accuracy but uses more memory. Syncfusion processes simple PDFs faster with lower memory usage but lacks advanced features.

Do these libraries require additional components for file conversions?

IronPDF includes a built-in DocxToPdfRenderer for DOCX to PDF conversion. Syncfusion requires additional components like Syncfusion.DocIO for Word conversions.

Jacob Mellor, Chief Technology Officer @ Team Iron
Jacob Mellor
  Chat with engineering team now
Chief Technology Officer

Jacob Mellor is Chief Technology Officer at Iron Software and a visionary engineer pioneering C# PDF technology. As the original developer behind Iron Software's core codebase, he has shaped the company's product architecture since its inception, transforming it alongside CEO Cameron Rimington into a 50+ person company serving NASA, Tesla, ...Read More

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