Iron Suite vs Foxit PDF SDK

PDF Rendering

PDF rendering (turning an existing PDF document into pixels for display, thumbnailing, or downstream image-based processing) is one of Foxit's headline capabilities. Foxit's native engine renders pages multi-threaded directly to bitmaps without an external dependency on a browser engine.

// Foxit PDF SDK — render existing PDF to bitmap
using foxit;
using foxit.common;
using foxit.common.fxcrt;
using foxit.pdf;

Library.Initialize(sn, key);

using PDFDoc doc = new PDFDoc("input.pdf");
doc.Load(null);
PDFPage page = doc.GetPage(0);
page.StartParse((int)PDFPage.ParseFlags.e_ParsePageNormal, null, false);

int width = (int)page.GetWidth();
int height = (int)page.GetHeight();
Matrix2D matrix = page.GetDisplayMatrix(0, 0, width, height, page.GetRotation());

Bitmap bitmap = new Bitmap(width, height, Bitmap.DIBFormat.e_DIBArgb, IntPtr.Zero, 0);
bitmap.FillRect(0xFFFFFFFF, null);
Renderer renderer = new Renderer(bitmap, false);
renderer.StartRender(page, matrix, null);
Library.Release();

// Foxit PDF SDK — render existing PDF to bitmap
using foxit;
using foxit.common;
using foxit.common.fxcrt;
using foxit.pdf;

Library.Initialize(sn, key);

using PDFDoc doc = new PDFDoc("input.pdf");
doc.Load(null);
PDFPage page = doc.GetPage(0);
page.StartParse((int)PDFPage.ParseFlags.e_ParsePageNormal, null, false);

int width = (int)page.GetWidth();
int height = (int)page.GetHeight();
Matrix2D matrix = page.GetDisplayMatrix(0, 0, width, height, page.GetRotation());

Bitmap bitmap = new Bitmap(width, height, Bitmap.DIBFormat.e_DIBArgb, IntPtr.Zero, 0);
bitmap.FillRect(0xFFFFFFFF, null);
Renderer renderer = new Renderer(bitmap, false);
renderer.StartRender(page, matrix, null);
Library.Release();

Imports foxit
Imports foxit.common
Imports foxit.common.fxcrt
Imports foxit.pdf

Library.Initialize(sn, key)

Using doc As New PDFDoc("input.pdf")
    doc.Load(Nothing)
    Dim page As PDFPage = doc.GetPage(0)
    page.StartParse(CInt(PDFPage.ParseFlags.e_ParsePageNormal), Nothing, False)

    Dim width As Integer = CInt(page.GetWidth())
    Dim height As Integer = CInt(page.GetHeight())
    Dim matrix As Matrix2D = page.GetDisplayMatrix(0, 0, width, height, page.GetRotation())

    Dim bitmap As New Bitmap(width, height, Bitmap.DIBFormat.e_DIBArgb, IntPtr.Zero, 0)
    bitmap.FillRect(&HFFFFFFFF, Nothing)
    Dim renderer As New Renderer(bitmap, False)
    renderer.StartRender(page, matrix, Nothing)
End Using

Library.Release()

// Iron Suite — IronPDF (HTML-to-PDF generation as the primary path)
using IronPdf;

var renderer = new ChromePdfRenderer();
string html = "<h1>Invoice 2026-0428</h1><p>Total due: $1,240.00</p>";
using var pdf = renderer.RenderHtmlAsPdf(html);
pdf.SaveAs("invoice.pdf");

// Iron Suite — IronPDF (HTML-to-PDF generation as the primary path)
using IronPdf;

var renderer = new ChromePdfRenderer();
string html = "<h1>Invoice 2026-0428</h1><p>Total due: $1,240.00</p>";
using var pdf = renderer.RenderHtmlAsPdf(html);
pdf.SaveAs("invoice.pdf");

Imports IronPdf

Dim renderer As New ChromePdfRenderer()
Dim html As String = "<h1>Invoice 2026-0428</h1><p>Total due: $1,240.00</p>"
Using pdf = renderer.RenderHtmlAsPdf(html)
    pdf.SaveAs("invoice.pdf")
End Using

Foxit's API surface reflects its native C++ origins: explicit Library.Initialize / Library.Release, manual matrix construction, bitmap allocation, and a multi-step render call. IronPDF's path is reversed; generate the PDF from HTML-to-PDF conversion through a bundled Chromium engine, then operate on the resulting document. Foxit excels at fidelity-rendering existing PDFs at scale; IronPDF excels at producing new PDFs from web-styled inputs. IronPDF's bundled Chromium ships in a single NuGet package (no separate Chromium install pipeline and no runtime BrowserFetcher download), which is operationally simpler than juggling Chromium-on-host or Puppeteer/Playwright runtime downloads in Linux container and AWS Lambda deployments.

PDF Editing (Page Manipulation)

Inserting, removing, and reordering pages is a routine operation in any PDF workflow, assembling reports from multiple sources, removing draft pages before publication, or building cover sheets onto an existing document.

// Foxit PDF SDK — insert / remove pages
using foxit.common;
using foxit.pdf;

Library.Initialize(sn, key);
using PDFDoc doc = new PDFDoc("input.pdf");
doc.Load(null);

PDFPage inserted = doc.InsertPage(1, 612f, 792f);
int lastIndex = doc.GetPageCount() - 1;
doc.RemovePage(lastIndex);

doc.SaveAs("edited.pdf", (int)PDFDoc.SaveFlags.e_SaveFlagNormal);
Library.Release();

// Foxit PDF SDK — insert / remove pages
using foxit.common;
using foxit.pdf;

Library.Initialize(sn, key);
using PDFDoc doc = new PDFDoc("input.pdf");
doc.Load(null);

PDFPage inserted = doc.InsertPage(1, 612f, 792f);
int lastIndex = doc.GetPageCount() - 1;
doc.RemovePage(lastIndex);

doc.SaveAs("edited.pdf", (int)PDFDoc.SaveFlags.e_SaveFlagNormal);
Library.Release();

Imports foxit.common
Imports foxit.pdf

Library.Initialize(sn, key)
Using doc As New PDFDoc("input.pdf")
    doc.Load(Nothing)

    Dim inserted As PDFPage = doc.InsertPage(1, 612.0F, 792.0F)
    Dim lastIndex As Integer = doc.GetPageCount() - 1
    doc.RemovePage(lastIndex)

    doc.SaveAs("edited.pdf", CInt(PDFDoc.SaveFlags.e_SaveFlagNormal))
End Using
Library.Release()

// NuGet: Install-Package IronPdf
// Docs: https://ironpdf.com/how-to/merge-or-split-pdfs/
using IronPdf;
using System.Collections.Generic;

class Program
{
    static void Main()
    {
        // PdfDocument.Merge accepts an array or params list of PdfDocument objects.
        // Order is preserved, and metadata, bookmarks, and annotations are retained.
        string[] inputs = { "invoice.pdf", "terms.pdf", "appendix.pdf" };

        List<PdfDocument> parts = new List<PdfDocument>();
        foreach (string path in inputs)
            parts.Add(PdfDocument.FromFile(path));

        PdfDocument merged = PdfDocument.Merge(parts.ToArray());
        merged.SaveAs("contract-package.pdf");
    }
}

// NuGet: Install-Package IronPdf
// Docs: https://ironpdf.com/how-to/merge-or-split-pdfs/
using IronPdf;
using System.Collections.Generic;

class Program
{
    static void Main()
    {
        // PdfDocument.Merge accepts an array or params list of PdfDocument objects.
        // Order is preserved, and metadata, bookmarks, and annotations are retained.
        string[] inputs = { "invoice.pdf", "terms.pdf", "appendix.pdf" };

        List<PdfDocument> parts = new List<PdfDocument>();
        foreach (string path in inputs)
            parts.Add(PdfDocument.FromFile(path));

        PdfDocument merged = PdfDocument.Merge(parts.ToArray());
        merged.SaveAs("contract-package.pdf");
    }
}

Imports IronPdf
Imports System.Collections.Generic

Module Program
    Sub Main()
        ' PdfDocument.Merge accepts an array or params list of PdfDocument objects.
        ' Order is preserved, and metadata, bookmarks, and annotations are retained.
        Dim inputs As String() = {"invoice.pdf", "terms.pdf", "appendix.pdf"}

        Dim parts As New List(Of PdfDocument)()
        For Each path As String In inputs
            parts.Add(PdfDocument.FromFile(path))
        Next

        Dim merged As PdfDocument = PdfDocument.Merge(parts.ToArray())
        merged.SaveAs("contract-package.pdf")
    End Sub
End Module

IronPDF exposes equivalent page-level operations through a unified PdfDocument object model: load via PdfDocument.FromFile(...), assemble via the static PdfDocument.Merge API, page-range copy and remove, and SaveAs(...). Edits hit the PDF object model directly; the HTML round-trip only happens when creating a PDF from HTML, not during manipulation. The contrast is structural: Foxit's per-operation API exposes native-engine plumbing (explicit Initialize/Release, save-flag enums); IronPDF unifies generation and editing under a single managed object model with implicit lifecycle management via using.

Office-to-PDF Conversion

Converting Word, Excel, and PowerPoint documents to PDF without a Microsoft Office install on the server is a frequent server-side requirement. Foxit handles this through a separately licensed Conversion add-on.

// Foxit PDF SDK — Conversion add-on (Word → PDF)
using foxit.common;
using foxit.addon.conversion;

Library.Initialize(sn, key);

using var settings = new Word2PDFSettingData();
Convert.FromWord("input.docx", string.Empty, "output.pdf", settings);

Library.Release();

// Foxit PDF SDK — Conversion add-on (Word → PDF)
using foxit.common;
using foxit.addon.conversion;

Library.Initialize(sn, key);

using var settings = new Word2PDFSettingData();
Convert.FromWord("input.docx", string.Empty, "output.pdf", settings);

Library.Release();

Imports foxit.common
Imports foxit.addon.conversion

Library.Initialize(sn, key)

Using settings As New Word2PDFSettingData()
    Convert.FromWord("input.docx", String.Empty, "output.pdf", settings)
End Using

Library.Release()

Iron Suite does not ship a single dedicated DOCX-to-PDF conversion API; the same outcome is achieved by composing IronWord (for any DOCX manipulation) with IronPDF (for the PDF generation), or by feeding the source content directly through IronPDF's HTML-to-PDF path. Foxit's Conversion add-on is the more direct route for teams who specifically need Office-source document conversion as a primary workflow, though it adds a separate add-on license to the seat fee.

OCR

OCR, extracting machine-readable text from scanned PDFs and raster images, is one of the most common reasons teams reach for a PDF SDK beyond pure generation.

// Foxit PDF SDK — OCR add-on
using foxit.common;
using foxit.addon.ocr;

Library.Initialize(sn, key);

if (OCREngine.Initialize("./ocr_resource") != ErrorCode.e_ErrSuccess) return;

OCREngine.SetLanguages("English");
// Configure OCRCallback to consume recognized content...

OCREngine.Release();
Library.Release();

// Foxit PDF SDK — OCR add-on
using foxit.common;
using foxit.addon.ocr;

Library.Initialize(sn, key);

if (OCREngine.Initialize("./ocr_resource") != ErrorCode.e_ErrSuccess) return;

OCREngine.SetLanguages("English");
// Configure OCRCallback to consume recognized content...

OCREngine.Release();
Library.Release();

Imports foxit.common
Imports foxit.addon.ocr

Library.Initialize(sn, key)

If OCREngine.Initialize("./ocr_resource") <> ErrorCode.e_ErrSuccess Then Return

OCREngine.SetLanguages("English")
' Configure OCRCallback to consume recognized content...

OCREngine.Release()
Library.Release()

// Iron Suite — IronOCR
using IronOcr;

var ocr = new IronTesseract();
using var input = new OcrInput("scanned-document.png");
input.Deskew();
input.DeNoise();

var result = ocr.Read(input);
Console.WriteLine($"Confidence: {result.Confidence}");
Console.WriteLine($"Extracted text: {result.Text}");

// Iron Suite — IronOCR
using IronOcr;

var ocr = new IronTesseract();
using var input = new OcrInput("scanned-document.png");
input.Deskew();
input.DeNoise();

var result = ocr.Read(input);
Console.WriteLine($"Confidence: {result.Confidence}");
Console.WriteLine($"Extracted text: {result.Text}");

Imports IronOcr

Dim ocr As New IronTesseract()
Using input As New OcrInput("scanned-document.png")
    input.Deskew()
    input.DeNoise()

    Dim result = ocr.Read(input)
    Console.WriteLine($"Confidence: {result.Confidence}")
    Console.WriteLine($"Extracted text: {result.Text}")
End Using

Foxit's OCR engine uses an explicit lifecycle (Initialize → SetLanguages → callback-based consumption → Release) with separately distributed resource files and a license key activated for the OCR module. IronOCR's API delivers the result directly with built-in preprocessing helpers (Deskew, DeNoise) and a single Read call. The trade-off mirrors the broader engine-vs-suite framing: Foxit gives more control over the OCR pipeline; IronOCR is faster to land on a working result.

Redaction

Production-grade redaction (permanently removing sensitive content from PDFs rather than overlaying black boxes that can be parsed back out) is one of Foxit's clearest specialist capabilities. It's used in legal, healthcare, and government workflows where the redacted output must withstand forensic recovery attempts.

// Foxit PDF SDK — Redaction add-on
using foxit.common;
using foxit.common.fxcrt;
using foxit.pdf;
using foxit.addon;
using foxit.pdf.annots;

Library.Initialize(sn, key);

using PDFDoc doc = new PDFDoc("input.pdf");
doc.Load(null);
PDFPage page = doc.GetPage(0);
page.StartParse((int)PDFPage.ParseFlags.e_ParsePageNormal, null, false);

Redaction redaction = new Redaction(doc);
RectFArray rects = new RectFArray();
rects.Add(new RectF(100, 100, 300, 130));
Redact redact = redaction.MarkRedactAnnot(page, rects);

if (redaction.Apply())
{
    doc.SaveAs("redacted.pdf", (int)PDFDoc.SaveFlags.e_SaveFlagNormal);
}
Library.Release();

// Foxit PDF SDK — Redaction add-on
using foxit.common;
using foxit.common.fxcrt;
using foxit.pdf;
using foxit.addon;
using foxit.pdf.annots;

Library.Initialize(sn, key);

using PDFDoc doc = new PDFDoc("input.pdf");
doc.Load(null);
PDFPage page = doc.GetPage(0);
page.StartParse((int)PDFPage.ParseFlags.e_ParsePageNormal, null, false);

Redaction redaction = new Redaction(doc);
RectFArray rects = new RectFArray();
rects.Add(new RectF(100, 100, 300, 130));
Redact redact = redaction.MarkRedactAnnot(page, rects);

if (redaction.Apply())
{
    doc.SaveAs("redacted.pdf", (int)PDFDoc.SaveFlags.e_SaveFlagNormal);
}
Library.Release();

Imports foxit.common
Imports foxit.common.fxcrt
Imports foxit.pdf
Imports foxit.addon
Imports foxit.pdf.annots

Library.Initialize(sn, key)

Using doc As New PDFDoc("input.pdf")
    doc.Load(Nothing)
    Dim page As PDFPage = doc.GetPage(0)
    page.StartParse(CInt(PDFPage.ParseFlags.e_ParsePageNormal), Nothing, False)

    Dim redaction As New Redaction(doc)
    Dim rects As New RectFArray()
    rects.Add(New RectF(100, 100, 300, 130))
    Dim redact As Redact = redaction.MarkRedactAnnot(page, rects)

    If redaction.Apply() Then
        doc.SaveAs("redacted.pdf", CInt(PDFDoc.SaveFlags.e_SaveFlagNormal))
    End If
End Using

Library.Release()

// NuGet: Install-Package IronPdf
// Docs: https://ironpdf.com/how-to/redact-text/
using IronPdf;

class Program
{
    static void Main()
    {
        PdfDocument pdf = PdfDocument.FromFile("employee-record.pdf");

        // RedactTextOnAllPages performs true redaction:
        // the text is removed from the PDF structure, not just covered visually.
        pdf.RedactTextOnAllPages("Jane Doe");
        pdf.RedactTextOnAllPages("123-45-6789");
        pdf.RedactTextOnAllPages("EMP-44213");

        pdf.SaveAs("employee-record-redacted.pdf");
    }
}

// NuGet: Install-Package IronPdf
// Docs: https://ironpdf.com/how-to/redact-text/
using IronPdf;

class Program
{
    static void Main()
    {
        PdfDocument pdf = PdfDocument.FromFile("employee-record.pdf");

        // RedactTextOnAllPages performs true redaction:
        // the text is removed from the PDF structure, not just covered visually.
        pdf.RedactTextOnAllPages("Jane Doe");
        pdf.RedactTextOnAllPages("123-45-6789");
        pdf.RedactTextOnAllPages("EMP-44213");

        pdf.SaveAs("employee-record-redacted.pdf");
    }
}

Imports IronPdf

Class Program
    Shared Sub Main()
        Dim pdf As PdfDocument = PdfDocument.FromFile("employee-record.pdf")

        ' RedactTextOnAllPages performs true redaction:
        ' the text is removed from the PDF structure, not just covered visually.
        pdf.RedactTextOnAllPages("Jane Doe")
        pdf.RedactTextOnAllPages("123-45-6789")
        pdf.RedactTextOnAllPages("EMP-44213")

        pdf.SaveAs("employee-record-redacted.pdf")
    End Sub
End Class

IronPDF supports text-level redaction via RedactTextOnAllPages (with regex pattern variants and page-specific overloads), removing the matched content from the PDF stream rather than only covering it visually. Foxit's Redaction.MarkRedactAnnot retains an area-based redaction edge: a RectF region on a page is marked and applied with redaction.Apply(), which fits workflows where the redaction target is a known visual region (signature blocks, header bars, redacted images) rather than a known string. For legal discovery and regulated-compliance workflows that need both string-based and area-based redaction in the same engine, Foxit has the broader API; for string-driven redaction of PII, identifiers, and account numbers, IronPDF's path is the more direct one.