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HTML ZIP to PDF in C# (.NET Guide)

#csharp #dotnet

Web projects ship as ZIP files—HTML, CSS, images, and JavaScript bundled together. Converting these archives to PDF without manual extraction simplifies deployment and document generation.

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

var renderer = new [ChromePdfRenderer](https://ironpdf.com/blog/videos/how-to-render-an-html-file-to-pdf-in-csharp-ironpdf/)();
var pdf = renderer.RenderZipFileAsPdf("website.zip", "index.html");
pdf.SaveAs("website.pdf");
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Point at the ZIP, specify the entry HTML file, get a PDF. All assets resolve automatically.

Why Convert ZIP Files to PDF?

Common scenarios:

  • Website archival - Preserve web pages as single documents
  • Email templates - Render bundled HTML email designs to PDF
  • Report packages - Convert exported HTML reports with assets
  • Documentation - Transform bundled docs into PDFs
  • Offline viewing - Create printable versions of web content

The alternative—extracting, fixing paths, rendering, cleaning up—is error-prone and tedious.

How Does ZIP Rendering Work?

The renderer:

  1. Opens the ZIP archive
  2. Locates the specified HTML entry
  3. Resolves relative paths to other files in the ZIP
  4. Renders everything to PDF

Your ZIP structure might look like:

project.zip
├── index.html
├── css/
│   └── styles.css
├── images/
│   ├── logo.png
│   └── banner.jpg
└── js/
    └── scripts.js
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The HTML file references assets with relative paths:

<link href="css/styles.css" rel="stylesheet">
<img src="images/logo.png">
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These paths work directly inside the ZIP—no extraction needed.

How Do I Structure My ZIP for Conversion?

Keep it simple with standard web project layout:

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

// ZIP structure:
// report.zip
// ├── report.html (main entry point)
// ├── styles.css
// └── charts/
//     ├── chart1.png
//     └── chart2.png

var renderer = new ChromePdfRenderer();
var pdf = renderer.RenderZipFileAsPdf("report.zip", "report.html");
pdf.SaveAs("report.pdf");
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The entry file must exist at the path you specify. Use forward slashes for nested paths.

How Do I Convert ZIPs from Memory?

For ZIPs received via API or generated dynamically:

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

// ZIP in memory (from API, database, etc.)
byte[] zipBytes = await httpClient.GetByteArrayAsync("https://api.example.com/report.zip");

// Save temporarily for rendering
var tempPath = Path.GetTempFileName() + ".zip";
File.WriteAllBytes(tempPath, zipBytes);

var renderer = new ChromePdfRenderer();
var pdf = renderer.RenderZipFileAsPdf(tempPath, "index.html");

// Clean up
File.Delete(tempPath);

return pdf.BinaryData;
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For frequent operations, use a temp directory with cleanup.

How Do I Create a ZIP for PDF Conversion?

Build the archive programmatically:

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

public byte[] GenerateReportPdf(ReportData data)
{
    var tempZip = Path.GetTempFileName() + ".zip";

    // Create ZIP with HTML and assets
    using (var archive = ZipFile.Open(tempZip, ZipArchiveMode.Create))
    {
        // Add main HTML
        var htmlEntry = archive.CreateEntry("report.html");
        using (var writer = new StreamWriter(htmlEntry.Open()))
        {
            writer.Write(GenerateHtml(data));
        }

        // Add CSS
        var cssEntry = archive.CreateEntry("styles.css");
        using (var writer = new StreamWriter(cssEntry.Open()))
        {
            writer.Write(GetReportCss());
        }

        // Add images from disk
        archive.CreateEntryFromFile("assets/logo.png", "images/logo.png");
        archive.CreateEntryFromFile("assets/header.png", "images/header.png");
    }

    // Convert to PDF
    var renderer = new ChromePdfRenderer();
    var pdf = renderer.RenderZipFileAsPdf(tempZip, "report.html");

    // Cleanup and return
    File.Delete(tempZip);
    return pdf.BinaryData;
}
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This pattern works well for dynamic reports with consistent branding.

How Do I Handle Nested HTML Files?

For ZIPs with HTML in subdirectories:

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

// ZIP structure:
// docs.zip
// ├── en/
// │   └── manual.html
// ├── fr/
// │   └── manual.html
// └── assets/
//     └── logo.png

var renderer = new ChromePdfRenderer();

// Render English version
var enPdf = renderer.RenderZipFileAsPdf("docs.zip", "en/manual.html");
enPdf.SaveAs("manual-en.pdf");

// Render French version
var frPdf = renderer.RenderZipFileAsPdf("docs.zip", "fr/manual.html");
frPdf.SaveAs("manual-fr.pdf");
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Use forward slashes for paths, even on Windows.

How Do I Convert Multiple Pages from One ZIP?

Process several HTML files from a single archive:

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

public void ConvertAllPages(string zipPath, string outputFolder)
{
    var renderer = new ChromePdfRenderer();

    // Find all HTML files in ZIP
    using var archive = ZipFile.OpenRead(zipPath);
    var htmlFiles = archive.Entries
        .Where(e => e.Name.EndsWith(".html", StringComparison.OrdinalIgnoreCase))
        .ToList();

    foreach (var entry in htmlFiles)
    {
        var pdf = renderer.RenderZipFileAsPdf(zipPath, entry.FullName);
        var outputName = Path.ChangeExtension(entry.Name, ".pdf");
        pdf.SaveAs(Path.Combine(outputFolder, outputName));
        pdf.Dispose();
    }
}
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Each HTML file becomes a separate PDF.

How Do I Merge ZIP Pages into One PDF?

Combine multiple HTML files from a ZIP into a single document:

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

public byte[] MergeZipToPdf(string zipPath, string[] htmlFiles)
{
    var renderer = new ChromePdfRenderer();
    var pdfs = new List<PdfDocument>();

    foreach (var htmlFile in htmlFiles)
    {
        var pdf = renderer.RenderZipFileAsPdf(zipPath, htmlFile);
        pdfs.Add(pdf);
    }

    var merged = PdfDocument.Merge(pdfs);

    // Cleanup
    foreach (var pdf in pdfs) pdf.Dispose();

    return merged.BinaryData;
}

// Usage
var combined = MergeZipToPdf("book.zip", new[]
{
    "chapters/intro.html",
    "chapters/chapter1.html",
    "chapters/chapter2.html",
    "chapters/conclusion.html"
});
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Order matters—pages appear in the order you process them.

How Do I Handle Missing Assets?

If assets are missing from the ZIP, the PDF renders without them:

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

var renderer = new ChromePdfRenderer();

// Enable console logging to see missing asset warnings
renderer.RenderingOptions.CustomCssUrl = null; // Ensure no external deps

try
{
    var pdf = renderer.RenderZipFileAsPdf("project.zip", "index.html");

    // Check page count to verify rendering worked
    if (pdf.PageCount == 0)
    {
        throw new Exception("Rendering produced empty PDF");
    }

    pdf.SaveAs("output.pdf");
}
catch (Exception ex)
{
    Console.WriteLine($"ZIP rendering failed: {ex.Message}");
    // Handle gracefully - maybe extract and retry
}
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Missing images render as broken image icons. Missing CSS means unstyled content.

How Do I Add Custom CSS to ZIP Content?

Override or extend styles in the ZIP:

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

var renderer = new ChromePdfRenderer();

// Add print-specific styles
renderer.RenderingOptions.CustomCssUrl = "file:///C:/styles/print-overrides.css";

// Or inject inline
renderer.RenderingOptions.HtmlHeader = new HtmlHeaderFooter
{
    HtmlFragment = @"
        <style>
            body { font-size: 12pt !important; }
            .no-print { display: none !important; }
        </style>"
};

var pdf = renderer.RenderZipFileAsPdf("website.zip", "index.html");
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Custom CSS applies after the ZIP's stylesheets.

What About MHTML Web Archives?

MHTML files (.mht, .mhtml) are single-file web archives. Handle them separately:

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

// MHTML is essentially HTML with embedded assets
// Read the file content
var mhtmlContent = File.ReadAllText("archive.mhtml");

// Some MHTML may work with RenderHtmlAsPdf directly
var renderer = new ChromePdfRenderer();
var pdf = renderer.RenderHtmlAsPdf(mhtmlContent);
pdf.SaveAs("archive.pdf");
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MHTML support varies—test with your specific files.

Quick Reference

Task Method
Convert ZIP to PDF RenderZipFileAsPdf(zipPath, htmlEntry)
Nested HTML Use forward slashes: "docs/page.html"
Multiple files Loop and merge results
Memory ZIP Write to temp file first

ZIP-to-PDF conversion keeps your web assets organized. Bundle once, render anywhere.

For the complete API reference, see the IronPDF ZIP documentation.

Written by Jacob Mellor, CTO at Iron Software. Jacob created IronPDF and leads a team of 50+ engineers building .NET document processing libraries.

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