COMPARISON

NReco.PdfGenerator vs IronPDF: Technical Comparison Guide

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Overview of NReco.PdfGenerator

NReco.PdfGenerator is a C# library that converts HTML documents into PDFs by utilizing the wkhtmltopdf command-line tool. It offers a straightforward API through its HtmlToPdfConverter class, which calls upon wkhtmltopdf for rendering.

The wkhtmltopdf tool employs WebKit Qt as its rendering engine, a version dating back to around 2012. Although widely used, development for wkhtmltopdf ceased in 2020, leaving it without security updates or new features. This poses challenges for teams developing modern applications with current CSS and JavaScript needs.

The free version of NReco.PdfGenerator includes watermarks on generated PDFs, necessitating a commercial license for production use. Obtaining pricing for these licenses involves contacting sales, which can complicate procurement processes.

Introduction to IronPDF

IronPDF is a .NET library that uses a modern Chromium-based rendering engine to convert HTML, CSS, and JavaScript into PDF documents. The ChromePdfRenderer class serves as the main interface for HTML-to-PDF conversion, offering extensive configuration options through the RenderingOptions property.

Unlike wkhtmltopdf wrappers, IronPDF's rendering engine receives regular updates for security and compatibility. The library is self-contained, eliminating the need to manage external binary dependencies across different platforms.

IronPDF offers a trial period with full functionality (no watermarks), allowing teams to evaluate capabilities before purchasing. Commercial licensing uses published, transparent pricing.

Comparing Rendering Engines

The primary difference between these libraries lies in their rendering engines, impacting security and CSS compatibility.

AspectNReco.PdfGeneratorIronPDF
Rendering EngineWebKit Qt (2012)Chromium (current)
Security20+ CVEs, abandonedActive security updates
CSS SupportCSS2.1, limited CSS3Full CSS3, Grid, Flexbox
JavaScriptBasic ES5Full ES6+
DependenciesExternal wkhtmltopdf binarySelf-contained
Async SupportSynchronous onlyFull async/await
Web FontsLimitedFull Google Fonts, @font-face
Free TrialWatermarkedFull functionality
Pricing TransparencyOpaque, contact salesPublished pricing

NReco.PdfGenerator inherits all security vulnerabilities from wkhtmltopdf, including documented CVEs for server-side request forgery, local file read vulnerabilities, and potential remote code execution. With wkhtmltopdf abandoned since 2020, no patches are available for these issues.

IronPDF's Chromium engine provides current web standards support, enabling modern CSS features like Grid and Flexbox layouts, CSS variables, and custom properties. JavaScript execution supports ES6+ syntax including async/await patterns.

Basic HTML to PDF Conversion

Both libraries handle basic HTML-to-PDF conversion, though with different API patterns.

NReco.PdfGenerator approach:

// NuGet: Install-Package NReco.PdfGenerator
using NReco.PdfGenerator;
using System.IO;

class Program
{
    static void Main()
    {
        var htmlToPdf = new HtmlToPdfConverter();
        var htmlContent = "<html><body><h1>Hello World</h1><p>This is a PDF document.</p></body></html>";
        var pdfBytes = htmlToPdf.GeneratePdf(htmlContent);
        File.WriteAllBytes("output.pdf", pdfBytes);
    }
}
// NuGet: Install-Package NReco.PdfGenerator
using NReco.PdfGenerator;
using System.IO;

class Program
{
    static void Main()
    {
        var htmlToPdf = new HtmlToPdfConverter();
        var htmlContent = "<html><body><h1>Hello World</h1><p>This is a PDF document.</p></body></html>";
        var pdfBytes = htmlToPdf.GeneratePdf(htmlContent);
        File.WriteAllBytes("output.pdf", pdfBytes);
    }
}
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IronPDF approach:

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

class Program
{
    static void Main()
    {
        var renderer = new ChromePdfRenderer();
        var htmlContent = "<html><body><h1>Hello World</h1><p>This is a PDF document.</p></body></html>";
        var pdf = renderer.RenderHtmlAsPdf(htmlContent);
        pdf.SaveAs("output.pdf");
    }
}
// NuGet: Install-Package IronPdf
using IronPdf;
using System.IO;

class Program
{
    static void Main()
    {
        var renderer = new ChromePdfRenderer();
        var htmlContent = "<html><body><h1>Hello World</h1><p>This is a PDF document.</p></body></html>";
        var pdf = renderer.RenderHtmlAsPdf(htmlContent);
        pdf.SaveAs("output.pdf");
    }
}
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Both libraries require minimal code for basic conversions. NReco.PdfGenerator returns a byte[] array requiring manual file operations, while IronPDF returns a PdfDocument object with convenient methods like SaveAs(). The IronPDF object also provides access to BinaryData for byte array access and Stream for stream-based operations.

For developers familiar with the HTML to PDF conversion workflow, IronPDF's API will feel intuitive while providing additional capabilities beyond basic conversion.

URL to PDF Conversion

Converting web pages to PDF documents reveals API differences in method naming and semantics.

NReco.PdfGenerator URL conversion:

// NuGet: Install-Package NReco.PdfGenerator
using NReco.PdfGenerator;
using System.IO;

class Program
{
    static void Main()
    {
        var htmlToPdf = new HtmlToPdfConverter();
        var pdfBytes = htmlToPdf.GeneratePdfFromFile("https://www.example.com", null);
        File.WriteAllBytes("webpage.pdf", pdfBytes);
    }
}
// NuGet: Install-Package NReco.PdfGenerator
using NReco.PdfGenerator;
using System.IO;

class Program
{
    static void Main()
    {
        var htmlToPdf = new HtmlToPdfConverter();
        var pdfBytes = htmlToPdf.GeneratePdfFromFile("https://www.example.com", null);
        File.WriteAllBytes("webpage.pdf", pdfBytes);
    }
}
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IronPDF URL conversion:

// NuGet: Install-Package IronPdf
using IronPdf;

class Program
{
    static void Main()
    {
        var renderer = new ChromePdfRenderer();
        var pdf = renderer.RenderUrlAsPdf("https://www.example.com");
        pdf.SaveAs("webpage.pdf");
    }
}
// NuGet: Install-Package IronPdf
using IronPdf;

class Program
{
    static void Main()
    {
        var renderer = new ChromePdfRenderer();
        var pdf = renderer.RenderUrlAsPdf("https://www.example.com");
        pdf.SaveAs("webpage.pdf");
    }
}
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NReco.PdfGenerator uses GeneratePdfFromFile() for both file paths and URLs, which can be semantically confusing. IronPDF provides a dedicated RenderUrlAsPdf method that clearly indicates the operation being performed.

Custom Page Size and Margins

Professional documents often require specific page dimensions and margin configurations. Both libraries support these customizations with different configuration patterns.

NReco.PdfGenerator page configuration:

// NuGet: Install-Package NReco.PdfGenerator
using NReco.PdfGenerator;
using System.IO;

class Program
{
    static void Main()
    {
        var htmlToPdf = new HtmlToPdfConverter();
        htmlToPdf.PageWidth = 210;
        htmlToPdf.PageHeight = 297;
        htmlToPdf.Margins = new PageMargins { Top = 10, Bottom = 10, Left = 10, Right = 10 };
        var htmlContent = "<html><body><h1>Custom Page Size</h1><p>A4 size document with margins.</p></body></html>";
        var pdfBytes = htmlToPdf.GeneratePdf(htmlContent);
        File.WriteAllBytes("custom-size.pdf", pdfBytes);
    }
}
// NuGet: Install-Package NReco.PdfGenerator
using NReco.PdfGenerator;
using System.IO;

class Program
{
    static void Main()
    {
        var htmlToPdf = new HtmlToPdfConverter();
        htmlToPdf.PageWidth = 210;
        htmlToPdf.PageHeight = 297;
        htmlToPdf.Margins = new PageMargins { Top = 10, Bottom = 10, Left = 10, Right = 10 };
        var htmlContent = "<html><body><h1>Custom Page Size</h1><p>A4 size document with margins.</p></body></html>";
        var pdfBytes = htmlToPdf.GeneratePdf(htmlContent);
        File.WriteAllBytes("custom-size.pdf", pdfBytes);
    }
}
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IronPDF page configuration:

// NuGet: Install-Package IronPdf
using IronPdf;
using IronPdf.Rendering;

class Program
{
    static void Main()
    {
        var renderer = new ChromePdfRenderer();
        renderer.RenderingOptions.PaperSize = PdfPaperSize.A4;
        renderer.RenderingOptions.MarginTop = 10;
        renderer.RenderingOptions.MarginBottom = 10;
        renderer.RenderingOptions.MarginLeft = 10;
        renderer.RenderingOptions.MarginRight = 10;
        var htmlContent = "<html><body><h1>Custom Page Size</h1><p>A4 size document with margins.</p></body></html>";
        var pdf = renderer.RenderHtmlAsPdf(htmlContent);
        pdf.SaveAs("custom-size.pdf");
    }
}
// NuGet: Install-Package IronPdf
using IronPdf;
using IronPdf.Rendering;

class Program
{
    static void Main()
    {
        var renderer = new ChromePdfRenderer();
        renderer.RenderingOptions.PaperSize = PdfPaperSize.A4;
        renderer.RenderingOptions.MarginTop = 10;
        renderer.RenderingOptions.MarginBottom = 10;
        renderer.RenderingOptions.MarginLeft = 10;
        renderer.RenderingOptions.MarginRight = 10;
        var htmlContent = "<html><body><h1>Custom Page Size</h1><p>A4 size document with margins.</p></body></html>";
        var pdf = renderer.RenderHtmlAsPdf(htmlContent);
        pdf.SaveAs("custom-size.pdf");
    }
}
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NReco.PdfGenerator requires specifying page dimensions in millimeters (210×297 for A4) and uses a PageMargins object. IronPDF uses the PdfPaperSize enum for standard sizes and provides individual margin properties through RenderingOptions. The RenderingOptions class centralizes all page configuration, making settings discoverable through IDE autocomplete.

API Mapping Reference

For teams considering NReco.PdfGenerator migration to IronPDF, understanding the API mappings helps estimate effort and plan the transition.

Core Method Mappings

NReco.PdfGeneratorIronPDF
new HtmlToPdfConverter()new ChromePdfRenderer()
GeneratePdf(html)RenderHtmlAsPdf(html)
GeneratePdfFromFile(url, output)RenderUrlAsPdf(url)
GeneratePdfFromFile(path, output)RenderHtmlFileAsPdf(path)
(not supported)RenderHtmlAsPdfAsync(html)

Configuration Property Mappings

NReco.PdfGeneratorIronPDF
Orientation = PageOrientation.LandscapeRenderingOptions.PaperOrientation = PdfPaperOrientation.Landscape
Size = PageSize.A4RenderingOptions.PaperSize = PdfPaperSize.A4
Margins.Top = 10RenderingOptions.MarginTop = 10
Zoom = 0.9fRenderingOptions.Zoom = 90
PageHeaderHtml = "..."RenderingOptions.HtmlHeader
PageFooterHtml = "..."RenderingOptions.HtmlFooter

Placeholder Syntax Differences

Headers and footers often include dynamic content like page numbers. The placeholder syntax differs between libraries:

NReco.PdfGeneratorIronPDFPurpose
[page]{page}Current page number
[topage]{total-pages}Total page count
[date]{date}Current date
[time]{time}Current time
[title]{html-title}Document title
[webpage]{url}Source URL

Teams migrating from NReco.PdfGenerator need to update all header and footer templates with the new placeholder syntax.

Zoom Value Conversion

NReco.PdfGenerator uses float values (0.0-2.0) for zoom, while IronPDF uses percentage values:

// NReco: Zoom = 0.75f means 75%
// IronPDF: Zoom = 75 means 75%
int ironPdfZoom = (int)(nrecoZoom * 100);
// NReco: Zoom = 0.75f means 75%
// IronPDF: Zoom = 75 means 75%
int ironPdfZoom = (int)(nrecoZoom * 100);
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Async Support Comparison

Modern web applications benefit from asynchronous operations that don't block threads. This is particularly important in ASP.NET Core applications handling concurrent requests.

NReco.PdfGenerator provides synchronous-only operations, which can block web server threads during PDF generation:

// NReco.PdfGenerator - synchronous only
var pdfBytes = converter.GeneratePdf(html);  // Blocks thread
// NReco.PdfGenerator - synchronous only
var pdfBytes = converter.GeneratePdf(html);  // Blocks thread
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IronPDF supports full async/await patterns:

// IronPDF - async support
var pdf = await renderer.RenderHtmlAsPdfAsync(html);  // Non-blocking
await pdf.SaveAsAsync("output.pdf");
// IronPDF - async support
var pdf = await renderer.RenderHtmlAsPdfAsync(html);  // Non-blocking
await pdf.SaveAsAsync("output.pdf");
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For applications generating PDFs in response to HTTP requests, IronPDF's async support improves scalability by freeing threads during the rendering process.

Dependency and Deployment Differences

NReco.PdfGenerator requires the wkhtmltopdf binary to be available on the system. This creates deployment challenges:

  • Platform-specific binaries must be managed (Windows .exe, Linux .so, macOS .dylib)
  • Docker images require wkhtmltopdf installation
  • CI/CD pipelines need binary provisioning steps
  • Security scanners flag the known CVEs

IronPDF is self-contained as a NuGet package:

# IronPDF installation - complete
dotnet add package IronPdf

# NReco.PdfGenerator installation - plus binary management
dotnet add package NReco.PdfGenerator
# Plus: install wkhtmltopdf per platform
# IronPDF installation - complete
dotnet add package IronPdf

# NReco.PdfGenerator installation - plus binary management
dotnet add package NReco.PdfGenerator
# Plus: install wkhtmltopdf per platform
SHELL

Teams migrating from NReco.PdfGenerator can remove wkhtmltopdf binaries and simplify their deployment process.

When Teams Consider Moving from NReco.PdfGenerator to IronPDF

Several factors drive teams to evaluate IronPDF as an alternative to NReco.PdfGenerator:

Security Compliance: Organizations with security requirements face challenges when vulnerability scanners identify wkhtmltopdf CVEs. Since wkhtmltopdf is abandoned, these vulnerabilities have no remediation path within NReco.PdfGenerator. IronPDF's actively maintained Chromium engine receives security updates.

Modern CSS Requirements: Projects requiring CSS Grid, Flexbox, CSS variables, or other modern CSS features cannot use wkhtmltopdf's 2012-era WebKit engine. Web designers often produce layouts that render incorrectly or not at all in NReco.PdfGenerator.

JavaScript Compatibility: Applications generating PDFs with JavaScript-rendered content (charts, dynamic tables, calculated values) need modern JavaScript support. wkhtmltopdf's ES5 limitation prevents use of contemporary JavaScript libraries.

Async Application Architecture: ASP.NET Core applications benefit from async PDF generation to maintain thread efficiency. NReco.PdfGenerator's synchronous-only API can create scalability bottlenecks.

Deployment Simplification: Managing platform-specific wkhtmltopdf binaries across development, staging, and production environments adds operational complexity. Teams seek self-contained solutions that simplify CI/CD pipelines.

Pricing Clarity: Budget planning requires predictable costs. NReco.PdfGenerator's opaque pricing (contact sales) complicates procurement, while IronPDF's published pricing enables straightforward budgeting.

Installation Comparison

NReco.PdfGenerator installation:

Install-Package NReco.PdfGenerator
Install-Package NReco.PdfGenerator
SHELL

Plus platform-specific wkhtmltopdf binary installation and management.

IronPDF installation:

Install-Package IronPdf
Install-Package IronPdf
SHELL

IronPDF requires a license key configuration at application startup:

IronPdf.License.LicenseKey = "YOUR-LICENSE-KEY";
IronPdf.License.LicenseKey = "YOUR-LICENSE-KEY";
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Both libraries support .NET Framework 4.6.2+ and .NET Core/.NET 5+, making them compatible with modern .NET development targeting .NET 10 and C# 14.

Performance Considerations

IronPDF's Chromium engine has an initialization cost on first use (approximately 1.5 seconds for Chromium startup). Subsequent renders are significantly faster. For applications with latency-sensitive startup requirements, warming up the renderer at application initialization prevents this delay from affecting user-facing operations:

// Warm up at startup
new ChromePdfRenderer().RenderHtmlAsPdf("<html></html>");
// Warm up at startup
new ChromePdfRenderer().RenderHtmlAsPdf("<html></html>");
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NReco.PdfGenerator also has initialization overhead when spawning the wkhtmltopdf process, plus ongoing memory overhead from external process management.

Making the Decision

The choice between NReco.PdfGenerator and IronPDF depends on your specific requirements:

Consider NReco.PdfGenerator if: You have existing wkhtmltopdf-based workflows that work correctly, security scanner findings are acceptable in your environment, you don't need modern CSS or JavaScript features, and you can manage platform-specific binary deployment.

Consider IronPDF if: Security compliance requires addressing wkhtmltopdf CVEs, your designs use modern CSS features like Grid or Flexbox, you need async/await support for web applications, you want to simplify deployment by eliminating external binaries, or you prefer transparent licensing and pricing.

For teams building modern .NET applications in 2025 and planning toward 2026, IronPDF's actively maintained Chromium engine provides a foundation for current and future web standards compatibility.

Getting Started with IronPDF

To evaluate IronPDF for your PDF generation needs:

  1. Install the IronPDF NuGet package: Install-Package IronPdf
  2. Review the HTML to PDF tutorial for basic conversion patterns
  3. Explore URL to PDF conversion for web page capture
  4. Configure headers and footers for professional documents

The IronPDF tutorials provide comprehensive examples for common scenarios, and the API reference documents all available classes and methods.

Final Thoughts

NReco.PdfGenerator and IronPDF represent different eras of PDF generation technology. NReco.PdfGenerator wraps wkhtmltopdf's 2012 WebKit engine, carrying forward both its familiar API and its security vulnerabilities and rendering limitations. IronPDF uses a modern Chromium engine with active maintenance, current web standards support, and async capabilities.

For teams concerned about security compliance, modern CSS/JavaScript requirements, or deployment complexity, IronPDF provides a path forward without the technical debt of abandoned dependencies. The transition requires updating API calls and placeholder syntax, but eliminates the need to manage external binaries and addresses documented security vulnerabilities.

Evaluate both options against your specific requirements for security posture, rendering fidelity, async support, and deployment simplicity. Understanding the architectural differences outlined in this comparison will help you make an informed decision that aligns with your PDF generation needs and modernization goals.