COMPARISON

ActivePDF vs IronPDF: Technical Comparison Guide

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When .NET developers need robust PDF generation and manipulation capabilities, two libraries frequently appear in technical evaluations: ActivePDF and IronPDF. Both provide comprehensive PDF functionality for C# applications, but they differ significantly in architecture, API design, corporate trajectory, and modernization approach.

This comparison examines both libraries across technically relevant dimensions to help professional developers and architects make informed decisions for their .NET PDF requirements.

Understanding ActivePDF

ActivePDF has been a powerful PDF manipulation toolkit with a long history in the .NET ecosystem. The library enables developers to generate PDF files from various sources and customize documents with headers, footers, margins, and watermarks. ActivePDF uses a stateful API model centered around the Toolkit class, where developers open output files, add content, and explicitly close files when complete.

However, ActivePDF's acquisition by Foxit has introduced uncertainty about the product's long-term development trajectory. The transition period following the acquisition has raised concerns about licensing terms, support continuity, and the possibility of the toolkit becoming a legacy product.

Understanding IronPDF

IronPDF is an actively developed PDF library from Iron Software, designed with modern .NET environments in mind. The library enables developers to create PDFs from HTML, URLs, and various formats, supporting C#, .NET Core, and ASP.NET. IronPDF uses a fluent, functional API pattern that separates rendering concerns (ChromePdfRenderer) from document manipulation (PdfDocument).

IronPDF emphasizes ease of use with NuGet-based installation and a code-based licensing model. The company provides a transparent product roadmap and comprehensive documentation with extensive examples.

Architecture and API Design Comparison

The fundamental architectural difference between these .NET PDF libraries lies in their API philosophy and workflow patterns.

AspectActivePDFIronPDF
Company StatusAcquired by Foxit (uncertain future)Independent, clear roadmap
API PatternStateful (OpenOutputFile/CloseOutputFile)Fluent, functional API
Object ModelSingle Toolkit classSeparate ChromePdfRenderer + PdfDocument
InstallationManual DLL referencesSimple NuGet package
License ModelMachine-lockedCode-based key
.NET SupportLegacy .NET Framework focusFramework 4.6.2 to .NET 9
Return ValuesInteger error codesExceptions (standard .NET)

ActivePDF requires developers to manage file operations explicitly with OpenOutputFile() and CloseOutputFile() calls. IronPDF eliminates this pattern entirely—developers render content and call SaveAs() directly without managing file state.

Code Comparison: Common PDF Operations

URL to PDF Conversion

Converting web pages to PDF documents demonstrates the API differences clearly.

ActivePDF:

// NuGet: Install-Package APToolkitNET
using ActivePDF.Toolkit;
using System;

class Program
{
    static void Main()
    {
        Toolkit toolkit = new Toolkit();

        string url = "https://www.example.com";

        if (toolkit.OpenOutputFile("webpage.pdf") == 0)
        {
            toolkit.AddURL(url);
            toolkit.CloseOutputFile();
            Console.WriteLine("PDF from URL created successfully");
        }
    }
}
// NuGet: Install-Package APToolkitNET
using ActivePDF.Toolkit;
using System;

class Program
{
    static void Main()
    {
        Toolkit toolkit = new Toolkit();

        string url = "https://www.example.com";

        if (toolkit.OpenOutputFile("webpage.pdf") == 0)
        {
            toolkit.AddURL(url);
            toolkit.CloseOutputFile();
            Console.WriteLine("PDF from URL created successfully");
        }
    }
}
IRON VB CONVERTER ERROR developers@ironsoftware.com
$vbLabelText   $csharpLabel

IronPDF:

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

class Program
{
    static void Main()
    {
        var renderer = new ChromePdfRenderer();

        string url = "https://www.example.com";

        var pdf = renderer.RenderUrlAsPdf(url);
        pdf.SaveAs("webpage.pdf");

        Console.WriteLine("PDF from URL created successfully");
    }
}
// NuGet: Install-Package IronPdf
using IronPdf;
using System;

class Program
{
    static void Main()
    {
        var renderer = new ChromePdfRenderer();

        string url = "https://www.example.com";

        var pdf = renderer.RenderUrlAsPdf(url);
        pdf.SaveAs("webpage.pdf");

        Console.WriteLine("PDF from URL created successfully");
    }
}
IRON VB CONVERTER ERROR developers@ironsoftware.com
$vbLabelText   $csharpLabel

ActivePDF requires creating a Toolkit instance, calling OpenOutputFile() which returns an integer error code that must be checked, adding the URL with AddURL(), and explicitly calling CloseOutputFile(). IronPDF reduces this to three lines: instantiate the renderer, call RenderUrlAsPdf(), and save with SaveAs().

For advanced URL rendering options, explore the URL to PDF documentation.

HTML String to PDF Conversion

Converting HTML content to PDF reveals similar pattern differences.

ActivePDF:

// NuGet: Install-Package APToolkitNET
using ActivePDF.Toolkit;
using System;

class Program
{
    static void Main()
    {
        Toolkit toolkit = new Toolkit();

        string htmlContent = "<html><body><h1>Hello World</h1></body></html>";

        if (toolkit.OpenOutputFile("output.pdf") == 0)
        {
            toolkit.AddHTML(htmlContent);
            toolkit.CloseOutputFile();
            Console.WriteLine("PDF created successfully");
        }
    }
}
// NuGet: Install-Package APToolkitNET
using ActivePDF.Toolkit;
using System;

class Program
{
    static void Main()
    {
        Toolkit toolkit = new Toolkit();

        string htmlContent = "<html><body><h1>Hello World</h1></body></html>";

        if (toolkit.OpenOutputFile("output.pdf") == 0)
        {
            toolkit.AddHTML(htmlContent);
            toolkit.CloseOutputFile();
            Console.WriteLine("PDF created successfully");
        }
    }
}
IRON VB CONVERTER ERROR developers@ironsoftware.com
$vbLabelText   $csharpLabel

IronPDF:

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

class Program
{
    static void Main()
    {
        var renderer = new ChromePdfRenderer();

        string htmlContent = "<html><body><h1>Hello World</h1></body></html>";

        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 = "<html><body><h1>Hello World</h1></body></html>";

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

        Console.WriteLine("PDF created successfully");
    }
}
IRON VB CONVERTER ERROR developers@ironsoftware.com
$vbLabelText   $csharpLabel

ActivePDF uses AddHTML() within the open/close file pattern with integer error code checking. IronPDF's RenderHtmlAsPdf() returns a PdfDocument object that can be saved, manipulated, or converted to bytes.

See the HTML to PDF conversion guide for advanced rendering scenarios.

PDF Merging Operations

Combining multiple PDF documents shows different approaches to document manipulation.

ActivePDF:

// NuGet: Install-Package APToolkitNET
using ActivePDF.Toolkit;
using System;

class Program
{
    static void Main()
    {
        Toolkit toolkit = new Toolkit();

        if (toolkit.OpenOutputFile("merged.pdf") == 0)
        {
            toolkit.AddPDF("document1.pdf");
            toolkit.AddPDF("document2.pdf");
            toolkit.CloseOutputFile();
            Console.WriteLine("PDFs merged successfully");
        }
    }
}
// NuGet: Install-Package APToolkitNET
using ActivePDF.Toolkit;
using System;

class Program
{
    static void Main()
    {
        Toolkit toolkit = new Toolkit();

        if (toolkit.OpenOutputFile("merged.pdf") == 0)
        {
            toolkit.AddPDF("document1.pdf");
            toolkit.AddPDF("document2.pdf");
            toolkit.CloseOutputFile();
            Console.WriteLine("PDFs merged successfully");
        }
    }
}
IRON VB CONVERTER ERROR developers@ironsoftware.com
$vbLabelText   $csharpLabel

IronPDF:

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

class Program
{
    static void Main()
    {
        var pdf1 = PdfDocument.FromFile("document1.pdf");
        var pdf2 = PdfDocument.FromFile("document2.pdf");

        var merged = PdfDocument.Merge(pdf1, pdf2);
        merged.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()
    {
        var pdf1 = PdfDocument.FromFile("document1.pdf");
        var pdf2 = PdfDocument.FromFile("document2.pdf");

        var merged = PdfDocument.Merge(pdf1, pdf2);
        merged.SaveAs("merged.pdf");

        Console.WriteLine("PDFs merged successfully");
    }
}
IRON VB CONVERTER ERROR developers@ironsoftware.com
$vbLabelText   $csharpLabel

ActivePDF uses the same stateful pattern with OpenOutputFile(), sequential AddPDF() calls, and CloseOutputFile(). IronPDF loads documents as PdfDocument objects and merges them with the static PdfDocument.Merge() method, returning a new document.

Explore additional merge operations in the PDF merging documentation.

Method Mapping Reference

For developers evaluating ActivePDF migration or comparing capabilities, this mapping shows equivalent operations across both libraries:

Core Document Operations

OperationActivePDF MethodIronPDF Method
Create toolkitnew Toolkit()new ChromePdfRenderer()
HTML to PDFtoolkit.AddHTML(html)renderer.RenderHtmlAsPdf(html)
URL to PDFtoolkit.AddURL(url)renderer.RenderUrlAsPdf(url)
Load PDFtoolkit.OpenInputFile(path)PdfDocument.FromFile(path)
Save PDFtoolkit.SaveAs(path)pdf.SaveAs(path)
Merge PDFstoolkit.AddPDF(file)PdfDocument.Merge(pdfs)
Page counttoolkit.GetPageCount()pdf.PageCount
Extract texttoolkit.GetText()pdf.ExtractAllText()
Add watermarktoolkit.AddWatermark(text)pdf.ApplyWatermark(html)
Encrypt PDFtoolkit.Encrypt(password)pdf.SecuritySettings.OwnerPassword

Page Configuration

ActivePDF SettingIronPDF Equivalent
toolkit.SetPageSize(612, 792)RenderingOptions.PaperSize = PdfPaperSize.Letter
toolkit.SetPageSize(595, 842)RenderingOptions.PaperSize = PdfPaperSize.A4
toolkit.SetOrientation("Landscape")RenderingOptions.PaperOrientation = Landscape
toolkit.SetMargins(t, b, l, r)RenderingOptions.MarginTop/Bottom/Left/Right

Note that ActivePDF uses points for page dimensions (612x792 = Letter), while IronPDF uses enums (PdfPaperSize.Letter) or millimeters for margins.

Key Technical Differences

File Operation Patterns

ActivePDF requires explicit file management:

// ActivePDF: Open/Close pattern required
Toolkit toolkit = new Toolkit();
if (toolkit.OpenOutputFile("output.pdf") == 0)
{
    toolkit.AddHTML("<h1>Hello World</h1>");
    toolkit.CloseOutputFile();  // Must not forget this
}
// ActivePDF: Open/Close pattern required
Toolkit toolkit = new Toolkit();
if (toolkit.OpenOutputFile("output.pdf") == 0)
{
    toolkit.AddHTML("<h1>Hello World</h1>");
    toolkit.CloseOutputFile();  // Must not forget this
}
IRON VB CONVERTER ERROR developers@ironsoftware.com
$vbLabelText   $csharpLabel

IronPDF eliminates this pattern entirely:

// IronPDF: No open/close needed
var renderer = new ChromePdfRenderer();
using var pdf = renderer.RenderHtmlAsPdf("<h1>Hello World</h1>");
pdf.SaveAs("output.pdf");  // 'using' handles cleanup
// IronPDF: No open/close needed
var renderer = new ChromePdfRenderer();
using var pdf = renderer.RenderHtmlAsPdf("<h1>Hello World</h1>");
pdf.SaveAs("output.pdf");  // 'using' handles cleanup
IRON VB CONVERTER ERROR developers@ironsoftware.com
$vbLabelText   $csharpLabel

Error Handling Conventions

ActivePDF returns integer error codes that developers must check:

// ActivePDF: Integer error codes
int result = toolkit.SomeMethod();
if (result != 0) { /* handle error */ }
// ActivePDF: Integer error codes
int result = toolkit.SomeMethod();
if (result != 0) { /* handle error */ }
IRON VB CONVERTER ERROR developers@ironsoftware.com
$vbLabelText   $csharpLabel

IronPDF uses standard .NET exceptions:

// IronPDF: Exception-based (standard .NET)
try
{
    var pdf = renderer.RenderHtmlAsPdf(html);
    pdf.SaveAs("output.pdf");
}
catch (Exception ex)
{
    // Handle error
}
// IronPDF: Exception-based (standard .NET)
try
{
    var pdf = renderer.RenderHtmlAsPdf(html);
    pdf.SaveAs("output.pdf");
}
catch (Exception ex)
{
    // Handle error
}
IRON VB CONVERTER ERROR developers@ironsoftware.com
$vbLabelText   $csharpLabel

Installation and Configuration

ActivePDF often requires manual DLL references and path configuration:

// ActivePDF: May require path configuration
var toolkit = new Toolkit(@"C:\Program Files\ActivePDF\...");
// ActivePDF: May require path configuration
var toolkit = new Toolkit(@"C:\Program Files\ActivePDF\...");
IRON VB CONVERTER ERROR developers@ironsoftware.com
$vbLabelText   $csharpLabel

IronPDF uses standard NuGet package management with zero configuration:

dotnet add package IronPdf
dotnet add package IronPdf
SHELL

License configuration is code-based:

IronPdf.License.LicenseKey = "YOUR-LICENSE-KEY";
IronPdf.License.LicenseKey = "YOUR-LICENSE-KEY";
IronPdf.License.LicenseKey = "YOUR-LICENSE-KEY"
$vbLabelText   $csharpLabel

When Teams Consider Moving from ActivePDF to IronPDF

Development teams evaluate transitioning from ActivePDF to IronPDF for several reasons:

Corporate Uncertainty: ActivePDF's acquisition by Foxit has created questions about long-term product direction, support continuity, and whether the toolkit may become a legacy product. Teams planning projects extending into 2026 and beyond consider this uncertainty when selecting dependencies.

Modernizing API Patterns: Organizations standardizing on modern .NET conventions find ActivePDF's stateful open/close pattern and integer error codes don't align with current practices. IronPDF's fluent API and exception-based error handling match contemporary .NET development patterns.

Licensing Flexibility: ActivePDF's machine-locked licensing can complicate cloud deployments, containerized environments, and CI/CD pipelines. IronPDF's code-based licensing key simplifies these scenarios.

Installation Simplification: Teams preferring NuGet-based package management over manual DLL references find IronPDF's installation approach cleaner to maintain across development environments.

Modern .NET Support: As organizations adopt .NET 10, C# 14, and newer framework versions, ensuring library compatibility becomes important. IronPDF explicitly supports .NET Framework 4.6.2 through .NET 9, positioning it for continued compatibility.

Feature Comparison Summary

FeatureActivePDFIronPDF
Development StagePotential legacy codebaseActively developed with regular updates
C# and .NET CompatibilityLegacy support for .NET environmentsFully supports modern .NET environments
Ease of InstallationMay require manual installation adjustmentsSimple installation via NuGet
Support and DocumentationVaries due to transitionComprehensive support and documentation
LicensingComplications due to acquisitionTransparent, clear licensing terms
Async SupportLimitedFull async support (RenderHtmlAsPdfAsync)

Strengths and Considerations

ActivePDF Strengths

  • Established Feature Set: ActivePDF provides comprehensive PDF manipulation features developed over many years
  • Existing User Base: Significant enterprise adoption means extensive real-world usage patterns exist
  • Comprehensive Capabilities: Handles complex PDF operations including forms, annotations, and security

ActivePDF Considerations

  • Uncertain Future: The Foxit acquisition raises questions about long-term development direction
  • Legacy Architecture: Stateful API patterns and integer error codes reflect older design philosophy
  • Licensing Complexity: Machine-locked licensing may complicate modern deployment scenarios

IronPDF Strengths

  • Active Development: Frequent updates and transparent roadmap provide confidence for long-term projects
  • Modern API Design: Fluent patterns, exception handling, and async support align with current .NET practices
  • Simple Integration: NuGet installation and code-based licensing simplify setup and deployment
  • Comprehensive Resources: Extensive tutorials and documentation support developer onboarding

Conclusion

ActivePDF and IronPDF both provide comprehensive PDF generation and manipulation capabilities for C# developers. ActivePDF offers an established feature set with significant enterprise adoption, while its acquisition by Foxit introduces uncertainty about future development.

IronPDF provides a modern API design with active development, transparent licensing, and strong support for current .NET versions. The fluent API patterns, exception-based error handling, and NuGet-based installation align with contemporary .NET development practices.

The choice between these libraries depends on specific project requirements: existing ActivePDF investments, tolerance for corporate uncertainty, API design preferences, and deployment environment considerations all factor into the decision.

For teams evaluating PDF libraries for new projects or considering modernization of existing PDF workflows, IronPDF's architecture aligns with contemporary .NET development practices while providing a clear path forward.

Start evaluating IronPDF with a free trial and explore the comprehensive documentation to assess fit for your specific requirements.