Migrating from fo.net (FO.NET) to IronPDF is a major update for your .NET PDF generation process. This guide offers a straightforward, step-by-step path to transition your codebase from outdated XSL-FO markup to modern HTML/CSS-based PDF generation, using skills your development team already has.
fo.net (FO.NET) is a C# port of an early Apache FOP build that converts XSL-FO documents to PDF. It is Apache 2.0-licensed but has several limitations for current development:
fo:block, fo:table, fo:page-sequence, etc.).Fonet package on nuget.org was last published in April 2011 (v1.0.0, .NET Framework 2.0). The community fork Fonet.Standard (.NET Standard 2.0) was last published in May 2020 (v1.0.5). The CodePlex repository is defunct and GitHub forks (prepare/FO.NET, nholik/FO.Net, hahmed/Fo.Net) are dormant.Fonet build depends on System.Drawing (GDI+) APIs that effectively limit it to Windows.| Aspect | fo.net (FO.NET) | IronPDF |
|---|---|---|
| Input Format | XSL-FO (outdated XML) | HTML/CSS (modern web standards) |
| Learning Curve | Steep (XSL-FO expertise) | Gentle (HTML/CSS knowledge) |
| Maintenance | Abandoned (last release May 2020) | Actively maintained |
| Platform Support | Windows only | Cross-platform (.NET Framework 4.6.2+, .NET Core 3.1+, .NET 5/6/7/8/9+) |
| CSS Support | None | Full CSS3 (Flexbox, Grid) |
| JavaScript | None | Full JavaScript support |
| URL Rendering | Not supported | Built-in |
| Modern Features | Limited | Headers, footers, watermarks, security |
| Documentation | Outdated | Thorough tutorials |
fo.net was designed when XSL-FO was expected to become a standard for document formatting. That expectation never materialized. HTML/CSS became the universal document format, while XSL-FO remained a niche skill - most XSL-FO resources date from 2005-2010, making maintenance increasingly difficult.
IronPDF lets you use the skills you already have to create professional PDFs on modern .NET.
# Create a backup branch
git checkout -b pre-ironpdf-migration
git add .
git commit -m "Backup before fo.net to IronPDF migration"# Find all fo.net references
grep -r "FonetDriver\|Fonet\|\.fo\"\|xsl-region" --include="*.cs" --include="*.csproj" .
# Find all XSL-FO template files
find . -name "*.fo" -o -name "*.xslfo" -o -name "*xsl-fo*"Before migration, catalog all XSL-FO files and note:
fo:static-content)# Remove fo.net package
dotnet remove package Fonet
dotnet remove package FO.NET
# Install IronPDF
dotnet add package IronPdf// Before (fo.net)
using Fonet;
using Fonet.Render.Pdf;
using System.Xml;
// After (IronPDF)
using IronPdf;
using IronPdf.Rendering;Imports IronPdf
Imports IronPdf.Rendering// Set license key at application startup
IronPdf.License.LicenseKey = "YOUR-LICENSE-KEY";' Set license key at application startup
IronPdf.License.LicenseKey = "YOUR-LICENSE-KEY"// Before (fo.net with XSL-FO)
FonetDriver driver = FonetDriver.Make();
using (FileStream output = new FileStream("output.pdf", FileMode.Create))
{
driver.Render(new StringReader(xslFoContent), output);
}
// After (IronPDF with HTML)
var renderer = new ChromePdfRenderer();
var pdf = renderer.RenderHtmlAsPdf(htmlContent);
pdf.SaveAs("output.pdf");Imports System.IO
Imports Fonet
Imports IronPdf
' Before (fo.net with XSL-FO)
Dim driver As FonetDriver = FonetDriver.Make()
Using output As FileStream = New FileStream("output.pdf", FileMode.Create)
driver.Render(New StringReader(xslFoContent), output)
End Using
' After (IronPDF with HTML)
Dim renderer As New ChromePdfRenderer()
Dim pdf = renderer.RenderHtmlAsPdf(htmlContent)
pdf.SaveAs("output.pdf")| fo.net Namespace | IronPDF Equivalent |
|---|---|
Fonet | IronPdf |
Fonet.Render.Pdf | IronPdf |
Fonet.Layout | N/A |
Fonet.Fo | N/A |
Fonet.Image | IronPdf |
| FonetDriver Method | IronPDF Equivalent |
|---|---|
FonetDriver.Make() | new ChromePdfRenderer() |
driver.Render(inputStream, outputStream) | renderer.RenderHtmlAsPdf(html) |
driver.Render(inputFile, outputStream) | renderer.RenderHtmlFileAsPdf(path) |
driver.BaseDirectory | RenderingOptions.BaseUrl |
driver.OnError += handler | Try/catch around render |
| fo.net (XSL-FO Attributes) | IronPDF RenderingOptions |
|---|---|
page-height | PaperSize or SetCustomPaperSize() |
page-width | PaperSize |
margin-top | MarginTop |
margin-bottom | MarginBottom |
margin-left | MarginLeft |
margin-right | MarginRight |
reference-orientation | PaperOrientation |
The fundamental shift in this fo.net migration is converting XSL-FO elements to their HTML equivalents:
| XSL-FO Element | HTML/CSS Equivalent |
|---|---|
<fo:root> | <html> |
<fo:layout-master-set> | CSS @page rule |
<fo:simple-page-master> | CSS @page |
<fo:page-sequence> | <body> or <div> |
<fo:flow> | <main> or <div> |
<fo:static-content> | HtmlHeaderFooter |
<fo:block> | <p>, <div>, <h1>-<h6> |
<fo:inline> | <span> |
<fo:table> | <table> |
<fo:table-row> | <tr> |
<fo:table-cell> | <td>, <th> |
<fo:list-block> | <ul>, <ol> |
<fo:list-item> | <li> |
<fo:external-graphic> | <img> |
<fo:page-number> | {page} placeholder |
<fo:page-number-citation> | {total-pages} |
<fo:basic-link> | <a href> |
| XSL-FO Property | CSS Equivalent | Example |
|---|---|---|
font-family | font-family | Same syntax |
font-size | font-size | Same syntax |
font-weight | font-weight | bold, normal, 700 |
text-align | text-align | left, center, right, justify |
color | color | Hex, RGB, names |
background-color | background-color | Same syntax |
space-before | margin-top | Before element |
space-after | margin-bottom | After element |
start-indent | margin-left | Left indent |
keep-together | page-break-inside: avoid | Prevent breaks |
break-before="page" | page-break-before: always | Force page break |
Before (fo.net with XSL-FO):
// NuGet: Install-Package Fonet
using Fonet;
using Fonet.Render.Pdf;
using System.IO;
using System.Xml;
class Program
{
static void Main()
{
// fo.net requires XSL-FO format, not HTML
// First convert HTML to XSL-FO (manual process)
string xslFo = @"<?xml version='1.0' encoding='utf-8'?>
<fo:root xmlns:fo='http://www.w3.org/1999/XSL/Format'>
<fo:layout-master-set>
<fo:simple-page-master master-name='page'>
<fo:region-body/>
</fo:simple-page-master>
</fo:layout-master-set>
<fo:page-sequence master-reference='page'>
<fo:flow flow-name='xsl-region-body'>
<fo:block>Hello World</fo:block>
</fo:flow>
</fo:page-sequence>
</fo:root>";
FonetDriver driver = FonetDriver.Make();
driver.Render(new StringReader(xslFo),
new FileStream("output.pdf", FileMode.Create));
}
}' NuGet: Install-Package Fonet
Imports Fonet
Imports Fonet.Render.Pdf
Imports System.IO
Imports System.Xml
Class Program
Shared Sub Main()
' fo.net requires XSL-FO format, not HTML
' First convert HTML to XSL-FO (manual process)
Dim xslFo As String = "<?xml version='1.0' encoding='utf-8'?>" & _
"<fo:root xmlns:fo='http://www.w3.org/1999/XSL/Format'>" & _
"<fo:layout-master-set>" & _
"<fo:simple-page-master master-name='page'>" & _
"<fo:region-body/>" & _
"</fo:simple-page-master>" & _
"</fo:layout-master-set>" & _
"<fo:page-sequence master-reference='page'>" & _
"<fo:flow flow-name='xsl-region-body'>" & _
"<fo:block>Hello World</fo:block>" & _
"</fo:flow>" & _
"</fo:page-sequence>" & _
"</fo:root>"
Dim driver As FonetDriver = FonetDriver.Make()
driver.Render(New StringReader(xslFo),
New FileStream("output.pdf", FileMode.Create))
End Sub
End ClassAfter (IronPDF with HTML):
// NuGet: Install-Package IronPdf
using IronPdf;
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");
}
}Imports IronPdf
Class Program
Shared Sub Main()
Dim renderer = New ChromePdfRenderer()
Dim html As String = "<h1>Hello World</h1><p>This is HTML content.</p>"
Dim pdf = renderer.RenderHtmlAsPdf(html)
pdf.SaveAs("output.pdf")
End Sub
End ClassThe IronPDF approach reduces 25+ lines of XSL-FO markup to just 4 lines of clean C# code. For more HTML to PDF options, see the IronPDF HTML to PDF documentation.
Before (fo.net with XSL-FO):
// NuGet: Install-Package Fonet
using Fonet;
using Fonet.Render.Pdf;
using System.IO;
class Program
{
static void Main()
{
// fo.net settings are configured in XSL-FO markup
string xslFo = @"<?xml version='1.0' encoding='utf-8'?>
<fo:root xmlns:fo='http://www.w3.org/1999/XSL/Format'>
<fo:layout-master-set>
<fo:simple-page-master master-name='A4'
page-height='297mm' page-width='210mm'
margin-top='20mm' margin-bottom='20mm'
margin-left='25mm' margin-right='25mm'>
<fo:region-body/>
</fo:simple-page-master>
</fo:layout-master-set>
<fo:page-sequence master-reference='A4'>
<fo:flow flow-name='xsl-region-body'>
<fo:block font-size='14pt'>Custom PDF</fo:block>
</fo:flow>
</fo:page-sequence>
</fo:root>";
FonetDriver driver = FonetDriver.Make();
driver.Render(new StringReader(xslFo),
new FileStream("custom.pdf", FileMode.Create));
}
}' NuGet: Install-Package Fonet
Imports Fonet
Imports Fonet.Render.Pdf
Imports System.IO
Class Program
Shared Sub Main()
' fo.net settings are configured in XSL-FO markup
Dim xslFo As String = "<?xml version='1.0' encoding='utf-8'?>
<fo:root xmlns:fo='http://www.w3.org/1999/XSL/Format'>
<fo:layout-master-set>
<fo:simple-page-master master-name='A4'
page-height='297mm' page-width='210mm'
margin-top='20mm' margin-bottom='20mm'
margin-left='25mm' margin-right='25mm'>
<fo:region-body/>
</fo:simple-page-master>
</fo:layout-master-set>
<fo:page-sequence master-reference='A4'>
<fo:flow flow-name='xsl-region-body'>
<fo:block font-size='14pt'>Custom PDF</fo:block>
</fo:flow>
</fo:page-sequence>
</fo:root>"
Dim driver As FonetDriver = FonetDriver.Make()
driver.Render(New StringReader(xslFo),
New FileStream("custom.pdf", FileMode.Create))
End Sub
End ClassAfter (IronPDF with HTML):
// NuGet: Install-Package IronPdf
using IronPdf;
using IronPdf.Engines.Chrome;
class Program
{
static void Main()
{
var renderer = new ChromePdfRenderer();
renderer.RenderingOptions.PaperSize = PdfPaperSize.A4;
renderer.RenderingOptions.MarginTop = 20;
renderer.RenderingOptions.MarginBottom = 20;
renderer.RenderingOptions.MarginLeft = 25;
renderer.RenderingOptions.MarginRight = 25;
string html = "<h1 style='font-size:14pt'>Custom PDF</h1>";
var pdf = renderer.RenderHtmlAsPdf(html);
pdf.SaveAs("custom.pdf");
}
}' NuGet: Install-Package IronPdf
Imports IronPdf
Imports IronPdf.Engines.Chrome
Module Program
Sub Main()
Dim renderer As New ChromePdfRenderer()
renderer.RenderingOptions.PaperSize = PdfPaperSize.A4
renderer.RenderingOptions.MarginTop = 20
renderer.RenderingOptions.MarginBottom = 20
renderer.RenderingOptions.MarginLeft = 25
renderer.RenderingOptions.MarginRight = 25
Dim html As String = "<h1 style='font-size:14pt'>Custom PDF</h1>"
Dim pdf = renderer.RenderHtmlAsPdf(html)
pdf.SaveAs("custom.pdf")
End Sub
End ModuleIronPDF provides programmatic rendering options instead of embedding configuration in XML markup.
Before (fo.net - not supported):
// NuGet: Install-Package Fonet
using Fonet;
using System.IO;
using System.Net;
class Program
{
static void Main()
{
// fo.net does not support URL rendering directly
// Must manually download, convert HTML to XSL-FO, then render
string url = "https://example.com";
string html = new WebClient().DownloadString(url);
// Manual conversion from HTML to XSL-FO required (complex)
string xslFo = ConvertHtmlToXslFo(html); // Not built-in
FonetDriver driver = FonetDriver.Make();
driver.Render(new StringReader(xslFo),
new FileStream("webpage.pdf", FileMode.Create));
}
static string ConvertHtmlToXslFo(string html)
{
// Custom implementation required - extremely complex
throw new System.NotImplementedException();
}
}' NuGet: Install-Package Fonet
Imports Fonet
Imports System.IO
Imports System.Net
Class Program
Shared Sub Main()
' fo.net does not support URL rendering directly
' Must manually download, convert HTML to XSL-FO, then render
Dim url As String = "https://example.com"
Dim html As String = New WebClient().DownloadString(url)
' Manual conversion from HTML to XSL-FO required (complex)
Dim xslFo As String = ConvertHtmlToXslFo(html) ' Not built-in
Dim driver As FonetDriver = FonetDriver.Make()
driver.Render(New StringReader(xslFo),
New FileStream("webpage.pdf", FileMode.Create))
End Sub
Shared Function ConvertHtmlToXslFo(html As String) As String
' Custom implementation required - extremely complex
Throw New System.NotImplementedException()
End Function
End ClassAfter (IronPDF - built-in support):
// NuGet: Install-Package IronPdf
using IronPdf;
class Program
{
static void Main()
{
var renderer = new ChromePdfRenderer();
var pdf = renderer.RenderUrlAsPdf("https://example.com");
pdf.SaveAs("webpage.pdf");
}
}Imports IronPdf
Class Program
Shared Sub Main()
Dim renderer = New ChromePdfRenderer()
Dim pdf = renderer.RenderUrlAsPdf("https://example.com")
pdf.SaveAs("webpage.pdf")
End Sub
End ClassURL to PDF rendering is one of the practical wins in this fo.net migration: IronPDF handles it natively with JavaScript execution. Learn more about URL to PDF conversion.
Before (fo.net with XSL-FO):
<fo:static-content flow-name="xsl-region-before">
<fo:block text-align="center" font-size="10pt">
Company Name - Confidential
</fo:block>
</fo:static-content>
<fo:static-content flow-name="xsl-region-after">
<fo:block text-align="right" font-size="10pt">
Page <fo:page-number/> of <fo:page-number-citation ref-id="last-page"/>
</fo:block>
</fo:static-content>After (IronPDF):
renderer.RenderingOptions.HtmlHeader = new HtmlHeaderFooter()
{
HtmlFragment = "<div style='text-align:center; font-size:10pt;'>Company Name - Confidential</div>",
DrawDividerLine = true
};
renderer.RenderingOptions.HtmlFooter = new HtmlHeaderFooter()
{
HtmlFragment = "<div style='text-align:right; font-size:10pt;'>Page {page} of {total-pages}</div>",
DrawDividerLine = true
};Imports System
renderer.RenderingOptions.HtmlHeader = New HtmlHeaderFooter() With {
.HtmlFragment = "<div style='text-align:center; font-size:10pt;'>Company Name - Confidential</div>",
.DrawDividerLine = True
}
renderer.RenderingOptions.HtmlFooter = New HtmlHeaderFooter() With {
.HtmlFragment = "<div style='text-align:right; font-size:10pt;'>Page {page} of {total-pages}</div>",
.DrawDividerLine = True
}IronPDF replaces complex XSL-FO region definitions with simple HTML headers and footers.
Before (fo.net):
// fo.net has very limited PDF security options
// Must use post-processing with another library' fo.net has very limited PDF security options
' Must use post-processing with another libraryAfter (IronPDF):
using IronPdf;
public byte[] GenerateSecurePdf(string html)
{
var renderer = new ChromePdfRenderer();
var pdf = renderer.RenderHtmlAsPdf(html);
// Set metadata
pdf.MetaData.Title = "Confidential Report";
pdf.MetaData.Author = "Company Name";
// Password protection
pdf.SecuritySettings.OwnerPassword = "owner123";
pdf.SecuritySettings.UserPassword = "user456";
// Restrict permissions
pdf.SecuritySettings.AllowUserCopyPasteContent = false;
pdf.SecuritySettings.AllowUserPrinting = IronPdf.Security.PdfPrintSecurity.NoPrint;
pdf.SecuritySettings.AllowUserEdits = IronPdf.Security.PdfEditSecurity.NoEdit;
return pdf.BinaryData;
}Imports IronPdf
Public Function GenerateSecurePdf(html As String) As Byte()
Dim renderer = New ChromePdfRenderer()
Dim pdf = renderer.RenderHtmlAsPdf(html)
' Set metadata
pdf.MetaData.Title = "Confidential Report"
pdf.MetaData.Author = "Company Name"
' Password protection
pdf.SecuritySettings.OwnerPassword = "owner123"
pdf.SecuritySettings.UserPassword = "user456"
' Restrict permissions
pdf.SecuritySettings.AllowUserCopyPasteContent = False
pdf.SecuritySettings.AllowUserPrinting = IronPdf.Security.PdfPrintSecurity.NoPrint
pdf.SecuritySettings.AllowUserEdits = IronPdf.Security.PdfEditSecurity.NoEdit
Return pdf.BinaryData
End FunctionFor optimal performance during your fo.net migration, reuse the ChromePdfRenderer instance:
// GOOD - Reuse the renderer
public class PdfService
{
private static readonly ChromePdfRenderer _renderer = new ChromePdfRenderer();
public byte[] Generate(string html) => _renderer.RenderHtmlAsPdf(html).BinaryData;
}
// BAD - Creating new instance each time
public byte[] GenerateBad(string html)
{
var renderer = new ChromePdfRenderer(); // Wasteful
return renderer.RenderHtmlAsPdf(html).BinaryData;
}Imports System
' GOOD - Reuse the renderer
Public Class PdfService
Private Shared ReadOnly _renderer As New ChromePdfRenderer()
Public Function Generate(html As String) As Byte()
Return _renderer.RenderHtmlAsPdf(html).BinaryData
End Function
End Class
' BAD - Creating new instance each time
Public Function GenerateBad(html As String) As Byte()
Dim renderer As New ChromePdfRenderer() ' Wasteful
Return renderer.RenderHtmlAsPdf(html).BinaryData
End Functionfo.net XSL-FO uses various units. IronPDF uses millimeters for margins. Here's a helper class:
public static class UnitConverter
{
public static double InchesToMm(double inches) => inches * 25.4;
public static double PointsToMm(double points) => points * 0.352778;
public static double PicasToMm(double picas) => picas * 4.233;
public static double CmToMm(double cm) => cm * 10;
}
// Usage
renderer.RenderingOptions.MarginTop = UnitConverter.InchesToMm(1); // 1 inchPublic Module UnitConverter
Public Function InchesToMm(inches As Double) As Double
Return inches * 25.4
End Function
Public Function PointsToMm(points As Double) As Double
Return points * 0.352778
End Function
Public Function PicasToMm(picas As Double) As Double
Return picas * 4.233
End Function
Public Function CmToMm(cm As Double) As Double
Return cm * 10
End Function
End Module
' Usage
renderer.RenderingOptions.MarginTop = UnitConverter.InchesToMm(1) ' 1 inchProblem: PDF page size looks different after fo.net migration.
Solution: Map XSL-FO page dimensions correctly:
// XSL-FO: page-height='11in' page-width='8.5in' (Letter)
renderer.RenderingOptions.PaperSize = PdfPaperSize.Letter;
// XSL-FO: page-height='297mm' page-width='210mm' (A4)
renderer.RenderingOptions.PaperSize = PdfPaperSize.A4;
// Custom size (in mm)
renderer.RenderingOptions.SetCustomPaperSize(210, 297);' XSL-FO: page-height='11in' page-width='8.5in' (Letter)
renderer.RenderingOptions.PaperSize = PdfPaperSize.Letter
' XSL-FO: page-height='297mm' page-width='210mm' (A4)
renderer.RenderingOptions.PaperSize = PdfPaperSize.A4
' Custom size (in mm)
renderer.RenderingOptions.SetCustomPaperSize(210, 297)Problem: Not sure what <fo:block> should become.
Solution: Use appropriate semantic HTML:
<h1> through <h6><p><div><span>Problem: Fonts look different from fo.net output.
Solution: Use web fonts or specify system fonts in CSS:
<style>
@import url('https://fonts.googleapis.com/css2?family=Roboto&display=swap');
body { font-family: 'Roboto', Arial, sans-serif; }
</style>Problem: <fo:page-number/> doesn't work.
Solution: Use IronPDF placeholders in headers/footers:
renderer.RenderingOptions.HtmlFooter = new HtmlHeaderFooter()
{
HtmlFragment = "<div style='text-align:center;'>Page {page} of {total-pages}</div>",
MaxHeight = 15 // mm
};Imports System
renderer.RenderingOptions.HtmlFooter = New HtmlHeaderFooter() With {
.HtmlFragment = "<div style='text-align:center;'>Page {page} of {total-pages}</div>",
.MaxHeight = 15 ' mm
}.fo, .xslfo)fo:static-content)Fonet or FO.NET package: dotnet remove package FonetIronPdf package: dotnet add package IronPdfFonet to IronPdfFonetDriver.Make() with new ChromePdfRenderer()driver.Render() with renderer.RenderHtmlAsPdf()pdf.SaveAs()fo:static-content to HtmlHeaderFooter<fo:page-number/> with {page} placeholder.fo and .xslfo template filesFor deeper coverage of the IronPDF surface used above, see the IronPDF API reference.
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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