ComPDFKit vs IronPDF: Technical Comparison Guide

HTML to PDF Conversion

Converting HTML content to PDF demonstrates the most significant capability difference between these libraries.

ComPDFKit:

// 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();
    }
}

IronPDF:

// 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");
    }
}

The contrast is striking. ComPDFKit requires creating a document, inserting a page with specific dimensions, getting an editor, beginning an edit session, creating a text widget, ending the edit, writing to file, and explicitly releasing the document. The comment in the ComPDFKit code explicitly notes that "Native HTML to PDF not directly supported."

IronPDF uses ChromePdfRenderer with RenderHtmlAsPdf() to directly convert HTML strings to PDF in a single method call. The Chromium engine renders HTML, CSS, and JavaScript exactly as a modern browser would.

For advanced HTML rendering options, explore the HTML to PDF conversion guide.

PDF Merging Operations

Combining multiple PDF documents shows different approaches to document manipulation.

ComPDFKit:

// 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();
    }
}

IronPDF:

// 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");
    }
}

ComPDFKit uses ImportPagesAtIndex() with a page range string format ("0-" + (document2.PageCount - 1)) and requires explicit Release() calls for both documents. IronPDF uses a static PdfDocument.Merge() method that accepts a collection of documents and returns a new merged document, with no manual cleanup required.

Explore additional merge operations in the PDF merging documentation.

Adding Watermarks

Watermarking documents demonstrates different API philosophies.

ComPDFKit:

// 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();
    }
}

IronPDF:

// 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");
    }
}

ComPDFKit requires manual iteration through all pages, getting an editor for each page, beginning/ending edit sessions, creating text areas, setting properties individually, and releasing each page and the document. IronPDF's ApplyWatermark() accepts HTML with CSS styling for the watermark content, along with rotation and alignment parameters, applying to all pages automatically.

Learn more about watermarking in the watermark documentation.

Core Operations

Document Operations

Memory Management

ComPDFKit requires explicit resource cleanup:

// ComPDFKit: Manual memory management required
var document = CPDFDocument.InitWithFilePath("input.pdf");
var page = document.PageAtIndex(0);
var textPage = page.GetTextPage();

// Must release all resources manually
textPage.Release();
page.Release();
document.Release();

// ComPDFKit: Manual memory management required
var document = CPDFDocument.InitWithFilePath("input.pdf");
var page = document.PageAtIndex(0);
var textPage = page.GetTextPage();

// Must release all resources manually
textPage.Release();
page.Release();
document.Release();

IronPDF uses automatic garbage collection:

// IronPDF: Automatic memory management
var pdf = PdfDocument.FromFile("input.pdf");
// No Release() needed - GC handles cleanup

// IronPDF: Automatic memory management
var pdf = PdfDocument.FromFile("input.pdf");
// No Release() needed - GC handles cleanup

This difference significantly impacts code maintainability and reduces the risk of memory leaks from forgotten Release() calls.

HTML Rendering Capability

ComPDFKit does not natively support HTML-to-PDF conversion:

// ComPDFKit: No native HTML support
var document = CPDFDocument.CreateDocument();
var page = document.InsertPage(0, 595, 842, "");
// Must manually parse HTML and create text/graphics elements
var editor = page.GetEditor();
editor.BeginEdit(CPDFEditType.EditText);
editor.CreateTextWidget(rect, "Manual text placement");
editor.EndEdit();

// ComPDFKit: No native HTML support
var document = CPDFDocument.CreateDocument();
var page = document.InsertPage(0, 595, 842, "");
// Must manually parse HTML and create text/graphics elements
var editor = page.GetEditor();
editor.BeginEdit(CPDFEditType.EditText);
editor.CreateTextWidget(rect, "Manual text placement");
editor.EndEdit();

IronPDF includes native Chromium rendering:

// IronPDF: Native HTML rendering with full CSS/JS support
var renderer = new ChromePdfRenderer();
var pdf = renderer.RenderHtmlAsPdf("<h1>Hello World</h1>");

// IronPDF: Native HTML rendering with full CSS/JS support
var renderer = new ChromePdfRenderer();
var pdf = renderer.RenderHtmlAsPdf("<h1>Hello World</h1>");

Page Access Patterns

Both libraries use 0-based page indexing, but with different access patterns:

// ComPDFKit: Method-based access
var page = document.PageAtIndex(0);

// IronPDF: Array-style access
var page = pdf.Pages[0];

// ComPDFKit: Method-based access
var page = document.PageAtIndex(0);

// IronPDF: Array-style access
var page = pdf.Pages[0];

ComPDFKit Strengths

• Cross-Platform Support: Windows, macOS, Android, iOS, and Linux coverage
• Comprehensive PDF Operations: Viewing, creating, editing, and converting capabilities
• Low-Level Control: Editor pattern provides granular content manipulation

ComPDFKit Considerations

• No Native HTML Rendering: Requires manual implementation for HTML-to-PDF
• Manual Memory Management: Explicit Release() calls required throughout
• Smaller Community: Limited Stack Overflow coverage and community resources
• Documentation Gaps: Some areas lack comprehensive guidance
• Verbose API: C++ influenced patterns require more boilerplate code

IronPDF Strengths

• Native Chromium Rendering: Full HTML, CSS3, and JavaScript support built-in
• Automatic Memory Management: No Release() calls needed
• Mature Ecosystem: 10+ years development, 10+ million downloads
• Modern .NET API: Fluent interfaces following contemporary patterns
• Extensive Resources: Comprehensive tutorials and documentation
• Large Community: Thousands of Stack Overflow answers and examples

IronPDF Considerations

• Chromium Dependency: Includes Chromium engine (larger package size)
• Different Paradigm: HTML-based approach versus low-level content manipulation