Convert HTML Files to PDF in .NET with IronPDF

Template-driven document generation

Keep an HTML template in your project (invoice, quote, certificate, contract), populate it, write it to disk, and render:

using IronPdf;

var renderer = new ChromePdfRenderer();
renderer.RenderHtmlFileAsPdf("templates/invoice-1042.html")
        .SaveAs("invoice-1042.pdf");

using IronPdf;

var renderer = new ChromePdfRenderer();
renderer.RenderHtmlFileAsPdf("templates/invoice-1042.html")
        .SaveAs("invoice-1042.pdf");

Imports IronPdf

Dim renderer As New ChromePdfRenderer()
renderer.RenderHtmlFileAsPdf("templates/invoice-1042.html").SaveAs("invoice-1042.pdf")

Because the source is a real file, ./logo.png and styles.css resolve naturally alongside it.

Rendering static-site and build output

Static site generators, Markdown pipelines, and documentation builders all produce HTML files. Point IronPDF at the output to turn a published page into an archivable PDF, with no need to re-fetch it over HTTP.

Designer-authored layouts

A designer hands over a self-contained HTML and CSS file; you render it as-is. Chrome drives the conversion, so the designer's browser preview matches the PDF, which removes a whole class of "it looked fine in the mockup" disputes.

Batch conversion of a folder

The method is one call per file, so converting a directory of reports or handouts is a short loop:

var renderer = new ChromePdfRenderer();

foreach (string file in Directory.GetFiles("reports", "*.html"))
{
    string output = Path.ChangeExtension(file, ".pdf");
    renderer.RenderHtmlFileAsPdf(file).SaveAs(output);
}

var renderer = new ChromePdfRenderer();

foreach (string file in Directory.GetFiles("reports", "*.html"))
{
    string output = Path.ChangeExtension(file, ".pdf");
    renderer.RenderHtmlFileAsPdf(file).SaveAs(output);
}

Imports System.IO
Imports IronPdf

Dim renderer As New ChromePdfRenderer()

For Each file As String In Directory.GetFiles("reports", "*.html")
    Dim output As String = Path.ChangeExtension(file, ".pdf")
    renderer.RenderHtmlFileAsPdf(file).SaveAs(output)
Next

Offline and air-gapped rendering

Because it reads from the local filesystem rather than a URL, this works where there is no outbound network: secure backends, CI runners, on-premise deployments. The HTML and its assets only need to be present on the machine.

Email-template proofing

Teams storing notification or email templates as HTML files can render them to PDF for review, sign-off, or record-keeping, without standing up a web server to view them.

The rule of thumb

IronPDF offers three entry points, and picking the wrong one is the most common source of broken assets:

• RenderHtmlFileAsPdf reads a file from disk; relative assets resolve from the file's location.
• RenderHtmlAsPdf takes an HTML string in memory; you usually set a base URL so assets resolve.
• RenderUrlAsPdf fetches over HTTP, and is where authentication, cookies, and logins apply.

Reach for the file method whenever your HTML already lives as a file. Configure output through RenderingOptions before rendering, and verify the page in Chrome first; if it renders there, it renders in the PDF.