MIGRATION GUIDES

How to Migrate from ComPDFKit to IronPDF in C#

Published:January 11, 2026

While ComPDFKit offers solid PDF manipulation features, several factors drive development teams to consider more established alternatives.

Market Maturity and Ecosystem Comparison

ComPDFKit faces challenges common to newer market entrants: documentation gaps, a smaller community, and limited Stack Overflow coverage. IronPDF's decade of refinement provides the stability and resources enterprise projects require.

Aspect	ComPDFKit	IronPDF
HTML-to-PDF	Requires manual HTML parsing	Native Chromium rendering
Market Maturity	Newer entrant	10+ years, battle-tested
Community Size	Smaller, limited Stack Overflow	Large, active community
Documentation	Some gaps	Extensive tutorials & guides
Downloads	Growing	10+ million NuGet downloads
API Style	C++ influenced, verbose	Modern .NET fluent API
Memory Management	Manual `Release()` calls	Automatic GC handling

Feature Parity

Both libraries support comprehensive PDF functionality:

Feature	ComPDFKit	IronPDF
HTML to PDF	Basic/Manual	✅ Native Chromium
URL to PDF	Manual implementation	✅ Built-in
Create PDF from scratch	✅	✅
PDF editing	✅	✅
Text extraction	✅	✅
Merge/Split	✅	✅
Digital signatures	✅	✅
Form filling	✅	✅
Watermarks	✅	✅
Cross-platform	Windows, Linux, macOS	Windows, Linux, macOS

Key Migration Benefits

Superior HTML Rendering: IronPDF's Chromium engine handles modern CSS3, JavaScript, and responsive layouts natively
Mature Ecosystem: 10+ years of refinement, extensive documentation, and proven stability
Simpler API: Less boilerplate code, no manual memory management with Release() calls
Better .NET Integration: Native async/await, LINQ support, fluent interfaces
Extensive Resources: Thousands of Stack Overflow answers and community examples

Pre-Migration Preparation

Prerequisites

Ensure your environment meets these requirements:

.NET Framework 4.6.2+ or .NET Core 3.1 / .NET 5-9
Visual Studio 2019+ or VS Code with C# extension
NuGet Package Manager access
IronPDF license key (free trial available at ironpdf.com)

Audit ComPDFKit Usage

Run these commands in your solution directory to identify all ComPDFKit references:

# Find all ComPDFKit usages in your codebase
grep -r "using ComPDFKit" --include="*.cs" .
grep -r "CPDFDocument\|CPDFPage\|CPDFAnnotation" --include="*.cs" .

# Find NuGet package references
grep -r "ComPDFKit" --include="*.csproj" .

# Find all ComPDFKit usages in your codebase
grep -r "using ComPDFKit" --include="*.cs" .
grep -r "CPDFDocument\|CPDFPage\|CPDFAnnotation" --include="*.cs" .

# Find NuGet package references
grep -r "ComPDFKit" --include="*.csproj" .

SHELL

Breaking Changes to Anticipate

Change	ComPDFKit	IronPDF	Impact
Document loading	`CPDFDocument.InitWithFilePath()`	`PdfDocument.FromFile()`	Method name change
Saving	`document.WriteToFilePath()`	`pdf.SaveAs()`	Method name change
Memory cleanup	`document.Release()` required	Automatic (GC)	Remove manual cleanup
Page access	`document.PageAtIndex(i)`	`pdf.Pages[i]`	Array-style access
Page indexing	0-based	0-based	No change needed
HTML rendering	Manual implementation	`RenderHtmlAsPdf()`	Major simplification
Text extraction	`textPage.GetText()`	`pdf.ExtractAllText()`	Simplified API

Step-by-Step Migration Process

Step 1: Update NuGet Packages

Remove ComPDFKit packages and install IronPDF:

# Remove ComPDFKit packages
dotnet remove package ComPDFKit.NetCore
dotnet remove package ComPDFKit.NetFramework

# Install IronPDF
dotnet add package IronPdf

# Remove ComPDFKit packages
dotnet remove package ComPDFKit.NetCore
dotnet remove package ComPDFKit.NetFramework

# Install IronPDF
dotnet add package IronPdf

SHELL

Step 2: Update Namespace References

Replace ComPDFKit namespaces with IronPDF:

// Remove these
using ComPDFKit.PDFDocument;
using ComPDFKit.PDFPage;
using ComPDFKit.PDFAnnotation;
using ComPDFKit.Import;

// Add this
using IronPdf;

// Remove these
using ComPDFKit.PDFDocument;
using ComPDFKit.PDFPage;
using ComPDFKit.PDFAnnotation;
using ComPDFKit.Import;

// Add this
using IronPdf;

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Step 3: Configure License

// Add at application startup (Program.cs or Global.asax)
IronPdf.License.LicenseKey = "YOUR-LICENSE-KEY";

// Add at application startup (Program.cs or Global.asax)
IronPdf.License.LicenseKey = "YOUR-LICENSE-KEY";

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Complete API Migration Reference

Document Operations

Task	ComPDFKit	IronPDF
Create empty document	`CPDFDocument.CreateDocument()`	`new PdfDocument()`
Load from file	`CPDFDocument.InitWithFilePath(path)`	`PdfDocument.FromFile(path)`
Load from stream	`CPDFDocument.InitWithStream(stream)`	`PdfDocument.FromStream(stream)`
Save to file	`document.WriteToFilePath(path)`	`pdf.SaveAs(path)`
Get page count	`document.PageCount`	`pdf.PageCount`
Release/Dispose	`document.Release()`	Not required

HTML to PDF Conversion

Task	ComPDFKit	IronPDF
HTML string to PDF	Manual implementation required	`renderer.RenderHtmlAsPdf(html)`
HTML file to PDF	Manual implementation required	`renderer.RenderHtmlFileAsPdf(path)`
URL to PDF	Manual implementation required	`renderer.RenderUrlAsPdf(url)`
Set page size	Via page creation parameters	`renderer.RenderingOptions.PaperSize`
Set margins	Via editor configuration	`renderer.RenderingOptions.MarginTop` etc.

Merge and Split Operations

Task	ComPDFKit	IronPDF
Merge documents	`doc1.ImportPagesAtIndex(doc2, range, index)`	`PdfDocument.Merge(pdf1, pdf2)`
Split document	Extract pages to new document	`pdf.CopyPages(start, end)`

Code Migration Examples

HTML to PDF Conversion

The most significant difference between ComPDFKit and IronPDF is HTML rendering. ComPDFKit requires manual text placement, while IronPDF renders HTML natively with its Chromium engine.

ComPDFKit Implementation:

// NuGet: Install-Package ComPDFKit.NetCore
using ComPDFKit.PDFDocument;
using System;

class Program
{
    static void Main()
    {
        var document = CPDFDocument.CreateDocument();
        var page = document.InsertPage(0, 595, 842, "");

        // ComPDFKit requires manual HTML rendering
        // Native HTML to PDF not directly supported
        var editor = page.GetEditor();
        editor.BeginEdit(CPDFEditType.EditText);
        editor.CreateTextWidget(new System.Drawing.RectangleF(50, 50, 500, 700), "HTML content here");
        editor.EndEdit();

        document.WriteToFilePath("output.pdf");
        document.Release();
    }
}

// NuGet: Install-Package ComPDFKit.NetCore
using ComPDFKit.PDFDocument;
using System;

class Program
{
    static void Main()
    {
        var document = CPDFDocument.CreateDocument();
        var page = document.InsertPage(0, 595, 842, "");

        // ComPDFKit requires manual HTML rendering
        // Native HTML to PDF not directly supported
        var editor = page.GetEditor();
        editor.BeginEdit(CPDFEditType.EditText);
        editor.CreateTextWidget(new System.Drawing.RectangleF(50, 50, 500, 700), "HTML content here");
        editor.EndEdit();

        document.WriteToFilePath("output.pdf");
        document.Release();
    }
}

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IronPDF Implementation:

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

class Program
{
    static void Main()
    {
        var renderer = new ChromePdfRenderer();
        var pdf = renderer.RenderHtmlAsPdf("<h1>Hello World</h1><p>This is HTML content.</p>");
        pdf.SaveAs("output.pdf");
    }
}

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

class Program
{
    static void Main()
    {
        var renderer = new ChromePdfRenderer();
        var pdf = renderer.RenderHtmlAsPdf("<h1>Hello World</h1><p>This is HTML content.</p>");
        pdf.SaveAs("output.pdf");
    }
}

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IronPDF's ChromePdfRenderer eliminates the need for manual text positioning and editor management. For more HTML conversion options, see the HTML to PDF documentation.

Merging Multiple PDFs

ComPDFKit Implementation:

// NuGet: Install-Package ComPDFKit.NetCore
using ComPDFKit.PDFDocument;
using ComPDFKit.Import;
using System;

class Program
{
    static void Main()
    {
        var document1 = CPDFDocument.InitWithFilePath("file1.pdf");
        var document2 = CPDFDocument.InitWithFilePath("file2.pdf");

        // Import pages from document2 into document1
        document1.ImportPagesAtIndex(document2, "0-" + (document2.PageCount - 1), document1.PageCount);

        document1.WriteToFilePath("merged.pdf");
        document1.Release();
        document2.Release();
    }
}

// NuGet: Install-Package ComPDFKit.NetCore
using ComPDFKit.PDFDocument;
using ComPDFKit.Import;
using System;

class Program
{
    static void Main()
    {
        var document1 = CPDFDocument.InitWithFilePath("file1.pdf");
        var document2 = CPDFDocument.InitWithFilePath("file2.pdf");

        // Import pages from document2 into document1
        document1.ImportPagesAtIndex(document2, "0-" + (document2.PageCount - 1), document1.PageCount);

        document1.WriteToFilePath("merged.pdf");
        document1.Release();
        document2.Release();
    }
}

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IronPDF Implementation:

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

class Program
{
    static void Main()
    {
        var pdf1 = PdfDocument.FromFile("file1.pdf");
        var pdf2 = PdfDocument.FromFile("file2.pdf");

        var merged = PdfDocument.Merge(new List<PdfDocument> { pdf1, pdf2 });
        merged.SaveAs("merged.pdf");
    }
}

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

class Program
{
    static void Main()
    {
        var pdf1 = PdfDocument.FromFile("file1.pdf");
        var pdf2 = PdfDocument.FromFile("file2.pdf");

        var merged = PdfDocument.Merge(new List<PdfDocument> { pdf1, pdf2 });
        merged.SaveAs("merged.pdf");
    }
}

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IronPDF's static Merge method eliminates the verbose ImportPagesAtIndex pattern with page range strings. For more options, see the PDF merging documentation.

Adding Watermarks

Watermarking demonstrates the paradigm shift from ComPDFKit's editor-based approach to IronPDF's HTML-based styling.

ComPDFKit Implementation:

// NuGet: Install-Package ComPDFKit.NetCore
using ComPDFKit.PDFDocument;
using ComPDFKit.PDFPage;
using System;
using System.Drawing;

class Program
{
    static void Main()
    {
        var document = CPDFDocument.InitWithFilePath("input.pdf");

        for (int i = 0; i < document.PageCount; i++)
        {
            var page = document.PageAtIndex(i);
            var editor = page.GetEditor();
            editor.BeginEdit(CPDFEditType.EditText);

            var textArea = editor.CreateTextArea();
            textArea.SetText("CONFIDENTIAL");
            textArea.SetFontSize(48);
            textArea.SetTransparency(128);

            editor.EndEdit();
            page.Release();
        }

        document.WriteToFilePath("watermarked.pdf");
        document.Release();
    }
}

// NuGet: Install-Package ComPDFKit.NetCore
using ComPDFKit.PDFDocument;
using ComPDFKit.PDFPage;
using System;
using System.Drawing;

class Program
{
    static void Main()
    {
        var document = CPDFDocument.InitWithFilePath("input.pdf");

        for (int i = 0; i < document.PageCount; i++)
        {
            var page = document.PageAtIndex(i);
            var editor = page.GetEditor();
            editor.BeginEdit(CPDFEditType.EditText);

            var textArea = editor.CreateTextArea();
            textArea.SetText("CONFIDENTIAL");
            textArea.SetFontSize(48);
            textArea.SetTransparency(128);

            editor.EndEdit();
            page.Release();
        }

        document.WriteToFilePath("watermarked.pdf");
        document.Release();
    }
}

$vbLabelText $csharpLabel

IronPDF Implementation:

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

class Program
{
    static void Main()
    {
        var pdf = PdfDocument.FromFile("input.pdf");

        pdf.ApplyWatermark("<h1 style='color:rgba(255,0,0,0.3);'>CONFIDENTIAL</h1>",
            rotation: 45,
            verticalAlignment: VerticalAlignment.Middle,
            horizontalAlignment: HorizontalAlignment.Center);

        pdf.SaveAs("watermarked.pdf");
    }
}

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

class Program
{
    static void Main()
    {
        var pdf = PdfDocument.FromFile("input.pdf");

        pdf.ApplyWatermark("<h1 style='color:rgba(255,0,0,0.3);'>CONFIDENTIAL</h1>",
            rotation: 45,
            verticalAlignment: VerticalAlignment.Middle,
            horizontalAlignment: HorizontalAlignment.Center);

        pdf.SaveAs("watermarked.pdf");
    }
}

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IronPDF reduces a 20+ line watermark implementation to a single method call with HTML/CSS styling. For more options, see the watermark documentation.

Text Extraction

ComPDFKit Implementation:

using ComPDFKit.PDFDocument;
using System.Text;

var document = CPDFDocument.InitWithFilePath("document.pdf");

// Extract text (verbose)
var allText = new StringBuilder();
for (int i = 0; i < document.PageCount; i++)
{
    var page = document.PageAtIndex(i);
    var textPage = page.GetTextPage();
    allText.AppendLine(textPage.GetText(0, textPage.CountChars()));
    textPage.Release();
    page.Release();
}

document.WriteToFilePath("output.pdf");
document.Release(); // Must remember to release!

using ComPDFKit.PDFDocument;
using System.Text;

var document = CPDFDocument.InitWithFilePath("document.pdf");

// Extract text (verbose)
var allText = new StringBuilder();
for (int i = 0; i < document.PageCount; i++)
{
    var page = document.PageAtIndex(i);
    var textPage = page.GetTextPage();
    allText.AppendLine(textPage.GetText(0, textPage.CountChars()));
    textPage.Release();
    page.Release();
}

document.WriteToFilePath("output.pdf");
document.Release(); // Must remember to release!

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IronPDF Implementation:

using IronPdf;

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

// Extract text (one-liner)
string allText = pdf.ExtractAllText();

pdf.SaveAs("output.pdf");
// No Release() needed - GC handles cleanup

using IronPdf;

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

// Extract text (one-liner)
string allText = pdf.ExtractAllText();

pdf.SaveAs("output.pdf");
// No Release() needed - GC handles cleanup

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IronPDF reduces multi-line text extraction with manual Release() calls to a single method. For more extraction options, see the text extraction documentation.

Password Protection

IronPDF Implementation:

using IronPdf;

var renderer = new ChromePdfRenderer();
var pdf = renderer.RenderHtmlAsPdf("<h1>Confidential Document</h1>");

// Set security
pdf.SecuritySettings.UserPassword = "userPassword";
pdf.SecuritySettings.OwnerPassword = "ownerPassword";
pdf.SecuritySettings.AllowUserPrinting = PdfPrintSecurity.FullPrintRights;
pdf.SecuritySettings.AllowUserCopyPasteContent = false;

pdf.SaveAs("protected.pdf");

using IronPdf;

var renderer = new ChromePdfRenderer();
var pdf = renderer.RenderHtmlAsPdf("<h1>Confidential Document</h1>");

// Set security
pdf.SecuritySettings.UserPassword = "userPassword";
pdf.SecuritySettings.OwnerPassword = "ownerPassword";
pdf.SecuritySettings.AllowUserPrinting = PdfPrintSecurity.FullPrintRights;
pdf.SecuritySettings.AllowUserCopyPasteContent = false;

pdf.SaveAs("protected.pdf");

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For comprehensive security options, see the encryption documentation.

Critical Migration Notes

Remove All Release() Calls

The most impactful change is removing manual memory management. ComPDFKit requires explicit Release() calls on documents, pages, and text pages. IronPDF handles this automatically through .NET garbage collection:

// ComPDFKit - manual cleanup required
document.Release();
page.Release();
textPage.Release();

// IronPDF - no equivalent needed
// GC handles cleanup automatically

// ComPDFKit - manual cleanup required
document.Release();
page.Release();
textPage.Release();

// IronPDF - no equivalent needed
// GC handles cleanup automatically

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Native HTML Rendering

ComPDFKit requires manual text placement with editor APIs. IronPDF renders HTML/CSS natively with its Chromium engine, supporting modern CSS3, JavaScript, and responsive layouts.

Same Page Indexing

Both libraries use 0-based indexing (Pages[0] is the first page)—no changes needed for page access code.

Simplified Text Extraction

Replace the multi-line GetTextPage() + GetText() + Release() pattern with a single ExtractAllText() call.

Fluent Merge API

Replace ImportPagesAtIndex(doc2, "0-9", pageCount) with simple Merge(pdf1, pdf2).

Post-Migration Checklist

After completing the code migration, verify the following:

Run all unit tests to verify PDF generation works correctly
Compare PDF output quality (IronPDF's Chromium engine may render differently—usually better)
Test HTML rendering with complex CSS and JavaScript
Verify text extraction accuracy
Test form functionality
Performance test batch operations
Test in all target environments
Update CI/CD pipelines
Remove ComPDFKit license files

Future-Proofing Your PDF Infrastructure

With .NET 10 on the horizon and C# 14 introducing new language features, choosing a mature, actively maintained PDF library ensures long-term compatibility. IronPDF's 10+ year track record, extensive community support, and modern API design means your migration investment pays dividends as projects extend into 2025 and 2026.

Additional Resources

Migrating from ComPDFKit to IronPDF eliminates manual memory management with Release() calls while providing native HTML-to-PDF rendering that ComPDFKit lacks. The transition to IronPDF's mature ecosystem delivers the documentation depth, community support, and proven stability that enterprise projects require.

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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How to Migrate from ComPDFKit to IronPDF in C#

Market Maturity and Ecosystem Comparison

Feature Parity

Key Migration Benefits

Pre-Migration Preparation

Prerequisites

Audit ComPDFKit Usage

Breaking Changes to Anticipate

Step-by-Step Migration Process

Step 1: Update NuGet Packages

Step 2: Update Namespace References

Step 3: Configure License

Complete API Migration Reference

Document Operations

HTML to PDF Conversion

Merge and Split Operations

Code Migration Examples

HTML to PDF Conversion

Merging Multiple PDFs

Adding Watermarks

Text Extraction

Password Protection

Critical Migration Notes

Remove All Release() Calls

Native HTML Rendering

Same Page Indexing

Simplified Text Extraction

Fluent Merge API

Post-Migration Checklist

Future-Proofing Your PDF Infrastructure

Additional Resources

How to Migrate from ComPDFKit to IronPDF in C#

Market Maturity and Ecosystem Comparison

Feature Parity

Key Migration Benefits

Pre-Migration Preparation

Prerequisites

Audit ComPDFKit Usage

Breaking Changes to Anticipate

Step-by-Step Migration Process

Step 1: Update NuGet Packages

Step 2: Update Namespace References

Step 3: Configure License

Complete API Migration Reference

Document Operations

HTML to PDF Conversion

Merge and Split Operations

Code Migration Examples

HTML to PDF Conversion

Merging Multiple PDFs

Adding Watermarks

Text Extraction

Password Protection

Critical Migration Notes

Remove All Release() Calls

Native HTML Rendering

Same Page Indexing

Simplified Text Extraction

Fluent Merge API

Post-Migration Checklist

Future-Proofing Your PDF Infrastructure

Additional Resources

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