最高のC# PDFライブラリを選ぶための究極のガイド

//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");

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 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");
    }
}

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

//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()

//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}");

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 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");
    }
}

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