Pdfium vs IronPDF: Technical Comparison Guide

What Is Pdfium?

Pdfium.NET is a .NET wrapper around Google's PDFium library, originally developed for Chromium. The library excels at PDF rendering—displaying PDF documents with high fidelity in .NET applications. It provides capabilities for viewing PDFs, extracting text, and rendering pages to images.

However, Pdfium's capabilities are fundamentally limited by its rendering-focused architecture. The library was designed to display PDFs, not create or manipulate them. This creates significant gaps for applications requiring PDF generation, document merging, or content modification.

Key characteristics of Pdfium.NET include:

• Viewing and Rendering Focus: Excels at displaying PDF content with high fidelity
• Performance: Uses Google's PDFium for efficient rendering
• Native Binary Dependencies: Requires platform-specific PDFium binaries (x86/x64)
• Deployment Complexity: Must bundle and manage native DLLs per platform

What Is IronPDF?

IronPDF is a complete .NET library providing full PDF lifecycle management. The ChromePdfRenderer class uses a modern Chromium-based engine to create PDFs from HTML, CSS, and JavaScript, while the PdfDocument class provides extensive manipulation capabilities.

Unlike Pdfium's rendering-only focus, IronPDF handles PDF creation, manipulation, merging, watermarking, security, and text extraction—all within a single library. The fully managed architecture eliminates native binary dependencies, simplifying deployment across platforms.

Architectural Comparison

The fundamental difference between Pdfium and IronPDF lies in their scope: rendering-only versus complete PDF solution.

For applications requiring only PDF viewing, Pdfium may suffice. For applications needing PDF generation, manipulation, or any creation capabilities, IronPDF provides a complete solution.

HTML to PDF Conversion

HTML-to-PDF conversion demonstrates the fundamental capability gap between these libraries.

Pdfium HTML-to-PDF approach:

// NuGet: Install-Package PdfiumViewer
using PdfiumViewer;
using System.IO;
using System.Drawing.Printing;

// Note: PdfiumViewer is primarily for viewing/rendering PDFs, not creating them from HTML
// For HTML to PDF with Pdfium.NET, you would need additional libraries
// This example shows a limitation of Pdfium.NET
class Program
{
    static void Main()
    {
        // Pdfium.NET does not have native HTML to PDF conversion
        // You would need to use a separate library to convert HTML to PDF
        // then use Pdfium for manipulation
        string htmlContent = "<h1>Hello World</h1>";

        // This functionality is not directly available in Pdfium.NET
        Console.WriteLine("HTML to PDF conversion not natively supported in Pdfium.NET");
    }
}

// NuGet: Install-Package PdfiumViewer
using PdfiumViewer;
using System.IO;
using System.Drawing.Printing;

// Note: PdfiumViewer is primarily for viewing/rendering PDFs, not creating them from HTML
// For HTML to PDF with Pdfium.NET, you would need additional libraries
// This example shows a limitation of Pdfium.NET
class Program
{
    static void Main()
    {
        // Pdfium.NET does not have native HTML to PDF conversion
        // You would need to use a separate library to convert HTML to PDF
        // then use Pdfium for manipulation
        string htmlContent = "<h1>Hello World</h1>";

        // This functionality is not directly available in Pdfium.NET
        Console.WriteLine("HTML to PDF conversion not natively supported in Pdfium.NET");
    }
}

IronPDF HTML-to-PDF approach:

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

class Program
{
    static void Main()
    {
        var renderer = new ChromePdfRenderer();
        string htmlContent = "<h1>Hello World</h1>";

        var pdf = renderer.RenderHtmlAsPdf(htmlContent);
        pdf.SaveAs("output.pdf");

        Console.WriteLine("PDF created successfully");
    }
}

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

class Program
{
    static void Main()
    {
        var renderer = new ChromePdfRenderer();
        string htmlContent = "<h1>Hello World</h1>";

        var pdf = renderer.RenderHtmlAsPdf(htmlContent);
        pdf.SaveAs("output.pdf");

        Console.WriteLine("PDF created successfully");
    }
}

Pdfium cannot create PDFs from HTML—it simply doesn't support this functionality. Applications requiring HTML to PDF conversion would need to combine Pdfium with additional libraries, creating complexity and potential compatibility issues.

IronPDF's ChromePdfRenderer uses a modern Chromium engine to convert HTML content with full support for CSS3, Flexbox, Grid, and JavaScript execution, producing high-fidelity PDF output from web content.

PDF Merging

Document merging demonstrates another significant capability gap.

Pdfium merge approach:

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

// Note: PdfiumViewer does not have native PDF merging functionality
// You would need to use additional libraries or implement custom logic
class Program
{
    static void Main()
    {
        List<string> pdfFiles = new List<string> 
        { 
            "document1.pdf", 
            "document2.pdf", 
            "document3.pdf" 
        };

        // PdfiumViewer is primarily for rendering/viewing
        // PDF merging is not natively supported
        // You would need to use another library like iTextSharp or PdfSharp

        Console.WriteLine("PDF merging not natively supported in PdfiumViewer");
    }
}

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

// Note: PdfiumViewer does not have native PDF merging functionality
// You would need to use additional libraries or implement custom logic
class Program
{
    static void Main()
    {
        List<string> pdfFiles = new List<string> 
        { 
            "document1.pdf", 
            "document2.pdf", 
            "document3.pdf" 
        };

        // PdfiumViewer is primarily for rendering/viewing
        // PDF merging is not natively supported
        // You would need to use another library like iTextSharp or PdfSharp

        Console.WriteLine("PDF merging not natively supported in PdfiumViewer");
    }
}

IronPDF merge approach:

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

class Program
{
    static void Main()
    {
        List<string> pdfFiles = new List<string> 
        { 
            "document1.pdf", 
            "document2.pdf", 
            "document3.pdf" 
        };

        var pdf = PdfDocument.Merge(pdfFiles);
        pdf.SaveAs("merged.pdf");

        Console.WriteLine("PDFs merged successfully");
    }
}

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

class Program
{
    static void Main()
    {
        List<string> pdfFiles = new List<string> 
        { 
            "document1.pdf", 
            "document2.pdf", 
            "document3.pdf" 
        };

        var pdf = PdfDocument.Merge(pdfFiles);
        pdf.SaveAs("merged.pdf");

        Console.WriteLine("PDFs merged successfully");
    }
}

Pdfium cannot merge PDF documents—the library lacks this functionality entirely. Applications needing PDF merging would require additional libraries, adding dependencies and complexity.

IronPDF's PdfDocument.Merge() method accepts a list of file paths or PdfDocument objects, combining them into a single document with a single method call.

Text Extraction

Text extraction is one area where both libraries provide functionality, though with different approaches and capabilities.

Pdfium text extraction approach:

// NuGet: Install-Package PdfiumViewer
using PdfiumViewer;
using System;
using System.IO;
using System.Text;

class Program
{
    static void Main()
    {
        string pdfPath = "document.pdf";

        using (var document = PdfDocument.Load(pdfPath))
        {
            StringBuilder text = new StringBuilder();

            for (int i = 0; i < document.PageCount; i++)
            {
                // Note: PdfiumViewer has limited text extraction capabilities
                // Text extraction requires additional work with Pdfium.NET
                string pageText = document.GetPdfText(i);
                text.AppendLine(pageText);
            }

            Console.WriteLine(text.ToString());
        }
    }
}

// NuGet: Install-Package PdfiumViewer
using PdfiumViewer;
using System;
using System.IO;
using System.Text;

class Program
{
    static void Main()
    {
        string pdfPath = "document.pdf";

        using (var document = PdfDocument.Load(pdfPath))
        {
            StringBuilder text = new StringBuilder();

            for (int i = 0; i < document.PageCount; i++)
            {
                // Note: PdfiumViewer has limited text extraction capabilities
                // Text extraction requires additional work with Pdfium.NET
                string pageText = document.GetPdfText(i);
                text.AppendLine(pageText);
            }

            Console.WriteLine(text.ToString());
        }
    }
}

IronPDF text extraction approach:

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

class Program
{
    static void Main()
    {
        string pdfPath = "document.pdf";

        var pdf = PdfDocument.FromFile(pdfPath);
        string text = pdf.ExtractAllText();

        Console.WriteLine(text);
    }
}

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

class Program
{
    static void Main()
    {
        string pdfPath = "document.pdf";

        var pdf = PdfDocument.FromFile(pdfPath);
        string text = pdf.ExtractAllText();

        Console.WriteLine(text);
    }
}

Pdfium provides text extraction through GetPdfText(), requiring manual iteration through pages and StringBuilder concatenation. The documentation notes that PdfiumViewer has "limited text extraction capabilities" that may require additional work.

IronPDF's ExtractAllText() method extracts all text from all pages in a single call, providing a simpler API for common use cases. For per-page access, IronPDF also provides pdf.Pages[index].Text.

API Mapping Reference

For teams considering Pdfium migration to IronPDF, understanding the API mappings helps estimate effort.

Native Binary Dependencies

A significant architectural difference lies in dependency management.

Pdfium deployment structure:

MyApp/
├── bin/
│   ├── MyApp.dll
│   ├── Pdfium.NET.dll
│   ├── x86/
│   │   └── pdfium.dll
│   └── x64/
│       └── pdfium.dll
├── runtimes/
│   ├── win-x86/native/
│   │   └── pdfium.dll
│   └── win-x64/native/
│       └── pdfium.dll

IronPDF deployment structure:

MyApp/
├── bin/
│   ├── MyApp.dll
│   └── IronPdf.dll  # Everything included

Pdfium requires bundling and managing platform-specific native binaries. This creates deployment complexity, especially for cross-platform applications or containerized environments. Each target platform needs the correct native DLL, and the application must correctly load the appropriate version at runtime.

IronPDF's fully managed architecture eliminates these concerns. The library handles its dependencies internally, simplifying deployment across Windows, Linux, and macOS.

Feature Comparison Summary

The scope difference between Pdfium and IronPDF spans virtually every PDF operation beyond basic viewing.

Applications requiring watermarking, headers and footers, or security settings cannot achieve these with Pdfium alone.

When Teams Consider Moving from Pdfium to IronPDF

Several factors drive teams to evaluate IronPDF as an alternative to Pdfium:

PDF Creation Requirements: Pdfium cannot create PDFs. Applications needing to generate PDFs from HTML templates, reports, or web content require additional libraries. IronPDF provides complete PDF creation with a modern Chromium engine.

Document Manipulation Needs: Pdfium cannot merge, split, or modify PDF content. As applications mature, requirements often expand beyond viewing to include document assembly, page extraction, or content modification.

Deployment Simplification: Managing native PDFium binaries across platforms adds complexity to build pipelines, deployment processes, and containerization. IronPDF's managed architecture eliminates this complexity.

Feature Expansion: Applications starting with viewing often need watermarking, security settings, or form filling. Adding these capabilities to a Pdfium-based application requires additional libraries, while IronPDF provides them natively.

Cross-Platform Consistency: Pdfium requires platform-specific binary management for each target environment. IronPDF's managed code works consistently across Windows, Linux, and macOS without platform-specific configuration.

Installation Comparison

Pdfium installation:

Install-Package PdfiumViewer

Install-Package PdfiumViewer

Plus manual management of native binaries.

IronPDF installation:

Install-Package IronPdf

Install-Package IronPdf

IronPDF requires a license key configuration at application startup:

IronPdf.License.LicenseKey = "YOUR-LICENSE-KEY";

IronPdf.License.LicenseKey = "YOUR-LICENSE-KEY";

Both libraries support .NET Framework and modern .NET versions, ensuring compatibility with applications targeting .NET 10 and C# 14.

Making the Decision

The choice between Pdfium and IronPDF depends on your application requirements:

Consider Pdfium if: You need only PDF viewing and rendering, don't require PDF creation or manipulation, are comfortable managing native binary dependencies, and have simple text extraction needs.

Consider IronPDF if: You need PDF creation from HTML or URLs, require PDF manipulation (merge, split, watermark), want simplified deployment without native dependencies, need advanced features (forms, security, signatures), or are building applications with expanding PDF requirements.

For most modern applications, the ability to create and manipulate PDFs is essential. Pdfium's rendering-only focus makes it insufficient for comprehensive PDF workflows without additional libraries. IronPDF's complete solution eliminates the need for library combinations while providing a unified API for all PDF operations.

Getting Started with IronPDF

To evaluate IronPDF for your PDF needs:

1. Install the IronPDF NuGet package: Install-Package IronPdf
2. Review the HTML to PDF tutorial for creation patterns
3. Explore PDF merging capabilities for document assembly
4. Check the tutorials section for comprehensive examples

The IronPDF documentation provides detailed guidance for common scenarios, and the API reference documents all available classes and methods.

Conclusion

Pdfium and IronPDF serve fundamentally different purposes in the .NET PDF ecosystem. Pdfium excels at PDF rendering—displaying documents with high fidelity using Google's PDFium engine. IronPDF provides a complete PDF solution covering creation, manipulation, and rendering in a single library.

For applications requiring only PDF viewing, Pdfium's focused approach may be appropriate. For applications needing PDF generation, document merging, watermarking, or any creation capabilities, IronPDF provides these features natively without requiring additional libraries.

The decision extends beyond current requirements to anticipated needs. Applications often start with viewing but expand to require creation and manipulation. Choosing IronPDF from the start provides a foundation for these expanded requirements while eliminating the complexity of native binary management that Pdfium introduces.

Evaluate your complete PDF requirements—current and anticipated—when selecting between these libraries. The rendering-only nature of Pdfium creates architectural limitations that become apparent as applications mature and requirements expand.