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Best C# PDF Libraries in 2025 (A Comparison)

#csharp #dotnet

Choosing a PDF library for .NET in 2025 feels overwhelming—there are dozens of options, each claiming to be the best. After working with most of them in production, I can tell you the differences matter more than you'd think.

Here's an honest comparison of the top C# PDF libraries based on real-world usage, not marketing claims.

What Are the Top C# PDF Libraries in 2025?

The leading libraries are:

  1. IronPDF — Chromium-based HTML-to-PDF specialist
  2. iTextSharp/iText — Low-level PDF manipulation, AGPL-licensed
  3. Aspose.PDF — Enterprise-grade, comprehensive feature set
  4. Syncfusion PDF — Part of Essential Studio, 15+ years in production
  5. PDFSharp — Open-source, MIT-licensed, basic PDF generation

Let's compare them feature-by-feature.

Which Library Is Best for HTML-to-PDF Conversion?

Winner: IronPDF

If your primary use case is converting HTML to PDF, IronPDF wins decisively. It uses Chromium rendering, the same engine as Google Chrome, so modern CSS (flexbox, grid, CSS variables) and JavaScript work perfectly.

using IronPdf;
// Install via NuGet: Install-Package IronPdf

var renderer = new [ChromePdfRenderer](https://ironpdf.com/blog/videos/how-to-render-html-string-to-pdf-in-csharp-ironpdf/)();
var pdf = renderer.RenderHtmlAsPdf("<h1>Hello from C#</h1>");
pdf.SaveAs("output.pdf");
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Why IronPDF beats competitors for HTML:

  • Modern CSS support: Bootstrap, Tailwind, Flexbox, CSS Grid all work
  • JavaScript execution: Renders SPAs, charts, dynamic content
  • Pixel-perfect rendering: What you see in Chrome is what you get in the PDF

iTextSharp's HTML support is limited:

// iTextSharp struggles with modern HTML
using (var document = new Document())
{
    PdfWriter.GetInstance(document, new FileStream("output.pdf", FileMode.Create));
    document.Open();

    // HTML parsing is rudimentary—complex CSS breaks
    var htmlWorker = new HTMLWorker(document);
    htmlWorker.Parse(new StringReader("<h1>Title</h1>"));

    document.Close();
}
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iTextSharp's HTML parser is outdated and doesn't support CSS3. You'll spend hours fighting with layout issues.

Aspose.PDF has better HTML support than iText but costs more:

Aspose supports HTML-to-PDF, but it's not Chromium-based, so rendering fidelity isn't as good as IronPDF. At Aspose's price point ($1,999+ per developer), IronPDF's HTML rendering is superior value.

Verdict: For HTML-to-PDF, use IronPDF. It's purpose-built for this and does it better than anyone else.

Which Library Has the Most Powerful Low-Level PDF API?

Winner: iTextSharp/iText

If you need granular control over PDF internals—custom font embedding, precise positioning, PDF/A compliance, form field manipulation—iTextSharp (or iText for Java) is unmatched.

using iText.Kernel.Pdf;
using iText.Layout;
using iText.Layout.Element;
// Install via NuGet: Install-Package itext7

var writer = new PdfWriter("output.pdf");
var pdf = new PdfDocument(writer);
var document = new Document(pdf);

document.Add(new Paragraph("Precise control over every element"));
document.Close();
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iText gives you complete control over PDF structure, but that control comes with complexity. Simple tasks require dozens of lines of code.

IronPDF's API is simpler but less granular:

IronPDF abstracts away low-level PDF details, which is great for 90% of use cases but limits you when you need precise control over PDF structure.

Aspose.PDF strikes a balance:

Aspose offers low-level control similar to iText but with a more modern API. However, its licensing cost ($1,999-$4,999 per developer) makes it impractical for many projects.

Verdict: If you need low-level PDF manipulation and can't afford Aspose, use iTextSharp. Be prepared for a steep learning curve.

Which Library Is Best for Commercial Applications?

Winner: IronPDF or Syncfusion (depending on use case)

IronPDF is the best choice for commercial apps focused on HTML-to-PDF conversion:

  • Licensing starts at $749/developer
  • Straightforward API reduces development time
  • Chromium rendering handles modern web content
  • No AGPL restrictions (you keep your source code private)

Syncfusion PDF is ideal if you need a full UI component suite:

  • Part of Essential Studio ($995/developer for entire suite)
  • Includes grid controls, charts, PDF library, and 100+ other components
  • 15+ years of production use
  • Enterprise support

iTextSharp's AGPL license is a deal-breaker for commercial apps:

iTextSharp is AGPL-licensed, which means if you use it, you must open-source your entire application. The commercial license costs $1,800+ per developer.

For most businesses, that's either a non-starter (open-sourcing proprietary code) or more expensive than IronPDF.

Aspose.PDF is enterprise-grade but expensive:

Aspose is powerful and reliable, but at $1,999-$4,999 per developer, it's only cost-effective for large enterprises with complex PDF requirements that justify the premium.

Verdict: For most commercial apps, IronPDF offers the best value. If you need a full component suite, Syncfusion wins.

Which Library Is Best for Open-Source Projects?

Winner: PDFSharp

PDFSharp is MIT-licensed, which means no restrictions, no revenue limits, no hidden costs.

using PdfSharp.Pdf;
using PdfSharp.Drawing;
// Install via NuGet: Install-Package PdfSharp

var document = new PdfDocument();
var page = document.AddPage();
var gfx = XGraphics.FromPdfPage(page);
var font = new XFont("Verdana", 20);

gfx.DrawString("Hello from PDFSharp", font, XBrushes.Black,
    new XRect(0, 0, page.Width, page.Height), XStringFormats.Center);

document.Save("output.pdf");
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Limitations:

  • No HTML-to-PDF (you build PDFs programmatically)
  • Basic features compared to commercial libraries
  • Less active development than commercial alternatives

When PDFSharp works:

  • Invoices, reports, tickets (structured layouts)
  • Open-source projects with no budget
  • Simple PDFs without complex styling

iTextSharp is technically free (AGPL), but:

The AGPL license requires you to open-source your project if you use iTextSharp. That's fine for open-source projects, but limits adoption and can complicate licensing if you ever want to offer a commercial version.

Verdict: For open-source projects, PDFSharp is safer than iTextSharp due to MIT licensing.

Which Library Has the Best Performance?

Winner: IronPDF (for HTML) and iTextSharp (for programmatic PDFs)

IronPDF's performance for HTML-to-PDF:

  • First render: ~2.8 seconds (Chromium initialization)
  • Subsequent renders: <1 second for simple documents
  • Throughput: 50-100+ PDFs per minute with parallel processing 
using IronPdf;
// Install via NuGet: Install-Package IronPdf

var renderer = new ChromePdfRenderer(); // Reuse this

for (int i = 0; i < 100; i++)
{
    var pdf = renderer.RenderHtmlAsPdf($"<h1>Document {i}</h1>");
    pdf.SaveAs($"doc-{i}.pdf");
}
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Reusing the renderer avoids re-initialization overhead, giving you 5-20x speedup.

iTextSharp is fast for programmatic PDF creation:

Since iTextSharp doesn't render HTML or execute JavaScript, it's lightweight and fast for structured PDF generation (invoices, reports).

Aspose.PDF is comparable to IronPDF in throughput:

Aspose performs well, but at its price point, performance alone doesn't justify the cost over IronPDF.

Verdict: For HTML-to-PDF, IronPDF is fastest. For programmatic generation, iTextSharp edges out slightly due to lower overhead.

What About Licensing Costs?

Here's the breakdown (2025 pricing, subject to change):

Library License Type Cost (per developer)
IronPDF Commercial $749+
iTextSharp AGPL (or commercial) Free (AGPL) / $1,800+ (commercial)
Aspose.PDF Commercial $1,999 - $4,999
Syncfusion PDF Commercial (with suite) $995 (entire Essential Studio)
PDFSharp MIT Free

Hidden costs to consider:

  • iTextSharp AGPL: Free if you open-source your app, but commercial license is expensive
  • Syncfusion: Best value if you need multiple components (grid, charts, PDF)
  • PDFSharp: Free but requires more development time (no HTML-to-PDF)
  • IronPDF: Mid-tier pricing, saves development time on HTML conversion

Which Library Works Best in Docker/Kubernetes?

Winner: IronPDF

IronPDF works in Docker with minimal configuration:

FROM mcr.microsoft.com/dotnet/aspnet:8.0

# Install Chromium dependencies
RUN apt-get update && apt-get install -y \
    libc6-dev \
    libgdiplus \
    libx11-dev \
    && rm -rf /var/lib/apt/lists/*

WORKDIR /app
COPY . .
ENTRYPOINT ["dotnet", "MyApp.dll"]
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iTextSharp is lightweight and Docker-friendly:

Since iTextSharp doesn't require browser binaries, it has a smaller footprint in containers.

Aspose.PDF also works in Docker but has the same deployment complexity as IronPDF without offering significantly better Docker support.

Verdict: Both IronPDF and iTextSharp work well in Docker, but IronPDF's HTML rendering capabilities make it more versatile.

Independent Testing: Who Actually Performs Best?

In independent testing by Microsoft developer advocate Jeff Fritz, Syncfusion, IronPDF, and Aspose all outperformed iTextSharp for HTML rendering quality.

Key findings:

  • IronPDF: Best HTML rendering fidelity (Chromium-based)
  • Syncfusion: Strong overall performance, great value with component suite
  • Aspose: Powerful but expensive
  • iTextSharp: Struggled with modern HTML/CSS

This aligns with my experience: iTextSharp is powerful for programmatic PDFs but terrible for HTML conversion.

Feature Comparison Table

Feature IronPDF iTextSharp Aspose.PDF Syncfusion PDFSharp
HTML to PDF ⭐⭐⭐⭐⭐ ⭐⭐ ⭐⭐⭐⭐ ⭐⭐⭐⭐ ❌
Modern CSS (Flexbox, Grid) ✅ ❌ ⚠️ ⚠️ ❌
JavaScript Execution ✅ ❌ ⚠️ ❌ ❌
Low-Level PDF Control ⚠️ ⭐⭐⭐⭐⭐ ⭐⭐⭐⭐⭐ ⭐⭐⭐⭐ ⭐⭐⭐
PDF Forms ✅ ✅ ✅ ✅ ⚠️
Digital Signatures ✅ ✅ ✅ ✅ ⚠️
PDF/A Compliance ✅ ✅ ✅ ✅ ❌
Performance (HTML) ⭐⭐⭐⭐⭐ ⭐⭐ ⭐⭐⭐⭐ ⭐⭐⭐⭐ N/A
Performance (Programmatic) ⭐⭐⭐⭐ ⭐⭐⭐⭐⭐ ⭐⭐⭐⭐ ⭐⭐⭐⭐ ⭐⭐⭐⭐⭐
Licensing Cost $$ AGPL or $$$ $$$$ $$ (suite) Free
Learning Curve Easy Steep Moderate Moderate Easy

My Recommendations by Use Case

Choose IronPDF if:

  • You need HTML-to-PDF conversion with modern CSS/JavaScript
  • You're building commercial web applications
  • You want simple APIs and fast development
  • Budget: $749+ per developer

Choose iTextSharp if:

  • You need low-level PDF control (form fields, precise positioning)
  • Your project is open-source (AGPL is acceptable)
  • You're not converting HTML to PDF
  • Budget: Free (AGPL) or $1,800+ (commercial)

Choose Aspose.PDF if:

  • You're an enterprise with complex PDF requirements
  • You need enterprise support and SLAs
  • Budget is not a primary constraint
  • Budget: $1,999+ per developer

Choose Syncfusion PDF if:

  • You need UI components (grids, charts) in addition to PDF generation
  • You want enterprise-grade support
  • You prefer buying a full suite over individual libraries
  • Budget: $995 per developer (entire Essential Studio)

Choose PDFSharp if:

  • You're building open-source software
  • You need basic PDF generation (no HTML conversion)
  • You have zero budget
  • Budget: Free (MIT license)

Final Verdict

For most .NET developers in 2025, IronPDF offers the best balance of features, performance, and price for HTML-to-PDF conversion.

If you need low-level PDF manipulation and can afford the licensing complexity, iTextSharp is still the industry standard.

For enterprises with complex requirements and budget to match, Aspose.PDF delivers comprehensive features and support.

For open-source projects or tight budgets, PDFSharp provides a solid MIT-licensed foundation for basic PDF needs.

The landscape has shifted from "iTextSharp is the only option" to "choose based on your use case." That's a good thing for developers.

Written by Jacob Mellor, CTO at Iron Software. Jacob created IronPDF and leads a team of 50+ engineers building .NET document processing libraries.

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