Gnostice vs IronPDF: Technical Comparison Guide

HTML to PDF Conversion

This operation demonstrates the core architectural difference in HTML handling.

Gnostice:

// NuGet: Install-Package Gnostice.PDFOne.DLL
using Gnostice.PDFOne;
using Gnostice.PDFOne.Graphics;
using System;

class Program
{
    static void Main()
    {
        PDFDocument doc = new PDFDocument();
        doc.Open();

        PDFPage page = doc.Pages.Add();

        // PDFOne doesn't have direct HTML to PDF conversion
        // You need to use Document Studio for HTML conversion
        // Or manually parse and render HTML elements

        PDFTextElement textElement = new PDFTextElement();
        textElement.Text = "Simple text conversion instead of HTML";
        textElement.Draw(page, 10, 10);

        doc.Save("output.pdf");
        doc.Close();
    }
}

// NuGet: Install-Package Gnostice.PDFOne.DLL
using Gnostice.PDFOne;
using Gnostice.PDFOne.Graphics;
using System;

class Program
{
    static void Main()
    {
        PDFDocument doc = new PDFDocument();
        doc.Open();

        PDFPage page = doc.Pages.Add();

        // PDFOne doesn't have direct HTML to PDF conversion
        // You need to use Document Studio for HTML conversion
        // Or manually parse and render HTML elements

        PDFTextElement textElement = new PDFTextElement();
        textElement.Text = "Simple text conversion instead of HTML";
        textElement.Draw(page, 10, 10);

        doc.Save("output.pdf");
        doc.Close();
    }
}

IronPDF:

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

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

        string html = "<h1>Hello World</h1><p>This is HTML content.</p>";

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

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

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

        string html = "<h1>Hello World</h1><p>This is HTML content.</p>";

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

The code comments explicitly state that PDFOne doesn't have direct HTML-to-PDF conversion. You need to use Document Studio for HTML conversion or manually parse and render HTML elements. This means creating pages manually, then drawing text elements at specific coordinates—essentially constructing PDFs programmatically rather than rendering HTML.

IronPDF creates a ChromePdfRenderer, passes an HTML string to RenderHtmlAsPdf(), and saves with SaveAs(). The Chromium engine renders HTML with full CSS, JavaScript, and modern web standards support.

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

Merging Multiple PDFs

PDF merging demonstrates the document lifecycle management differences.

Gnostice:

// NuGet: Install-Package Gnostice.PDFOne.DLL
using Gnostice.PDFOne;
using Gnostice.PDFOne.Document;
using System;

class Program
{
    static void Main()
    {
        PDFDocument doc1 = new PDFDocument();
        doc1.Load("document1.pdf");

        PDFDocument doc2 = new PDFDocument();
        doc2.Load("document2.pdf");

        PDFDocument mergedDoc = new PDFDocument();
        mergedDoc.Open();

        mergedDoc.Append(doc1);
        mergedDoc.Append(doc2);

        mergedDoc.Save("merged.pdf");

        doc1.Close();
        doc2.Close();
        mergedDoc.Close();
    }
}

// NuGet: Install-Package Gnostice.PDFOne.DLL
using Gnostice.PDFOne;
using Gnostice.PDFOne.Document;
using System;

class Program
{
    static void Main()
    {
        PDFDocument doc1 = new PDFDocument();
        doc1.Load("document1.pdf");

        PDFDocument doc2 = new PDFDocument();
        doc2.Load("document2.pdf");

        PDFDocument mergedDoc = new PDFDocument();
        mergedDoc.Open();

        mergedDoc.Append(doc1);
        mergedDoc.Append(doc2);

        mergedDoc.Save("merged.pdf");

        doc1.Close();
        doc2.Close();
        mergedDoc.Close();
    }
}

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");
    }
}

// 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");
    }
}

Gnostice requires creating separate PDFDocument instances, calling Load() on each source, creating a new empty PDFDocument, calling Open() on it, using Append() for each source document, then explicitly calling Close() on all three documents. This manual resource management pattern requires careful attention to prevent resource leaks.

IronPDF uses PdfDocument.FromFile() to load source documents and the static PdfDocument.Merge() method to combine them in a single call, returning a new merged document. The SaveAs() method handles output.

Adding Watermarks

Watermarking demonstrates the coordinate-based versus declarative styling approaches.

Gnostice:

// NuGet: Install-Package Gnostice.PDFOne.DLL
using Gnostice.PDFOne;
using Gnostice.PDFOne.Graphics;
using System;
using System.Drawing;

class Program
{
    static void Main()
    {
        PDFDocument doc = new PDFDocument();
        doc.Load("input.pdf");

        PDFFont font = new PDFFont(PDFStandardFont.Helvetica, 48);

        foreach (PDFPage page in doc.Pages)
        {
            PDFTextElement watermark = new PDFTextElement();
            watermark.Text = "CONFIDENTIAL";
            watermark.Font = font;
            watermark.Color = Color.FromArgb(128, 255, 0, 0);
            watermark.RotationAngle = 45;

            watermark.Draw(page, 200, 400);
        }

        doc.Save("watermarked.pdf");
        doc.Close();
    }
}

// NuGet: Install-Package Gnostice.PDFOne.DLL
using Gnostice.PDFOne;
using Gnostice.PDFOne.Graphics;
using System;
using System.Drawing;

class Program
{
    static void Main()
    {
        PDFDocument doc = new PDFDocument();
        doc.Load("input.pdf");

        PDFFont font = new PDFFont(PDFStandardFont.Helvetica, 48);

        foreach (PDFPage page in doc.Pages)
        {
            PDFTextElement watermark = new PDFTextElement();
            watermark.Text = "CONFIDENTIAL";
            watermark.Font = font;
            watermark.Color = Color.FromArgb(128, 255, 0, 0);
            watermark.RotationAngle = 45;

            watermark.Draw(page, 200, 400);
        }

        doc.Save("watermarked.pdf");
        doc.Close();
    }
}

IronPDF:

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

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

        var watermark = new TextStamper()
        {
            Text = "CONFIDENTIAL",
            FontSize = 48,
            Opacity = 50,
            Rotation = 45,
            VerticalAlignment = VerticalAlignment.Middle,
            HorizontalAlignment = HorizontalAlignment.Center
        };

        pdf.ApplyStamp(watermark);
        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");

        var watermark = new TextStamper()
        {
            Text = "CONFIDENTIAL",
            FontSize = 48,
            Opacity = 50,
            Rotation = 45,
            VerticalAlignment = VerticalAlignment.Middle,
            HorizontalAlignment = HorizontalAlignment.Center
        };

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

Gnostice requires creating a PDFFont object with PDFStandardFont.Helvetica and size, then iterating through pages with foreach (PDFPage page in doc.Pages), creating a PDFTextElement for each page with Text, Font, Color (using Color.FromArgb()), and RotationAngle properties, then calling Draw(page, x, y) with specific coordinates. Finally, Save() and Close() are required.

IronPDF uses PdfDocument.FromFile() to load, creates a TextStamper with declarative properties (Text, FontSize, Opacity, Rotation, VerticalAlignment, HorizontalAlignment), and calls ApplyStamp() once to apply to all pages automatically. No manual iteration or coordinate calculations are needed.

Learn more about watermarking in the IronPDF tutorials.

Core Class Mapping

Document Operations Mapping

Page and Content Operations

Gnostice Strengths

• Multi-Format Support: Handles various document formats beyond PDF
• Established Product: Long-standing commercial product
• Viewer Controls: Includes document viewer components

Gnostice Considerations

• No External CSS: External stylesheets not supported
• No JavaScript: Dynamic content cannot be rendered
• No RTL Languages: Arabic, Hebrew explicitly unsupported
• Platform Fragmentation: Different products for different platforms
• Memory Issues: Reported leaks and stability problems
• Coordinate-Based API: Manual positioning required
• PDFOne HTML Limitations: No direct HTML-to-PDF in PDFOne

IronPDF Strengths

• Full CSS Support: External stylesheets, Flexbox, Grid
• JavaScript Execution: Chromium-quality rendering
• Unicode Support: Including RTL languages
• Unified Library: Single product for all .NET platforms
• Declarative API: TextStamper with alignment properties, no coordinates
• Memory Stability: No reported memory management issues
• Comprehensive Resources: Extensive tutorials and documentation

IronPDF Considerations

• PDF-Focused: Focused on PDF rather than multi-format
• Commercial License: Required for production use