Convert HTML to PDF in C#

using EvoPdf.Next;

var converter = new HtmlToPdfConverter();

byte[] fromUrl = converter.ConvertUrl(
    "https://www.evopdf.com");

converter = new HtmlToPdfConverter();
byte[] fromHtml = converter.ConvertHtml(
    "<h1>Invoice 1042</h1><img src='logo.png'>",
    "https://www.example.com/assets/");

using EvoPdf.Next;

var converter = new HtmlToPdfConverter();

converter.ConvertUrlToFile(
    "https://www.evopdf.com", "page.pdf");

converter = new HtmlToPdfConverter();
converter.ConvertHtmlToFile(
    "<h1>Invoice 1042</h1>",
    "https://www.example.com/assets/",
    "invoice.pdf");

The second argument of ConvertHtml is the base URL. Relative paths in the HTML (logo.png, styles.css, fonts/inter.woff2) are resolved against it exactly as a browser would resolve them for a page served from that address. Pass null when the HTML string has no external resources or uses absolute URLs only. A local folder works too, as a file:/// URL.

Each method has an Async variant with the same name (ConvertUrlAsync, ConvertHtmlAsync and the ToFileAsync pair) that takes a CancellationToken and follows the task-based pattern. Because every conversion gets its own converter instance, running several in parallel is one Task.WhenAll:

string[] urls = { "https://example.com/report/1", "https://example.com/report/2", "https://example.com/report/3" };

Task<byte[]>[] tasks = urls
    .Select(u => new HtmlToPdfConverter().ConvertUrlAsync(u, CancellationToken.None))
    .ToArray();

byte[][] pdfs = await Task.WhenAll(tasks);

How many run at the same time is a single global setting; the rest is scheduling. The documentation topic Convert Multiple HTML Pages to PDF in Parallel has the full sample and the online demo runs it with your own list of pages.

var converter = new HtmlToPdfConverter();
var options = converter.PdfDocumentOptions;

// margins are in points, 72 points = 1 inch
options.LeftMargin = 36;
options.RightMargin = 36;
options.TopMargin = 54;
options.BottomMargin = 54;

// laid out at the width between the margins, no scaling
converter.LayoutAtPageWidth(PdfPageSize.A4, PdfPageOrientation.Portrait);

byte[] pdf = converter.ConvertUrl(url);

var converter = new HtmlToPdfConverter();

// the PDF page becomes as wide as a 1024 px browser window, content drawn 1:1;
// the second argument makes one tall page instead of paginated output
converter.PageWidthFromBrowserWindow(1024, singlePage: true);

byte[] pdf = converter.ConvertUrl(url);

The predefined sizes (A4, Letter, Legal, the A and B series, Arch and Ledger) are fields of PdfPageSize; a custom size takes the width and the height in points. If the HTML declares its own size in an @page CSS rule, set PreferCssPageSize to true and the converter follows the stylesheet. How the page size, the layout width and the zoom work together, with the settings for a web page on A4, a template designed for paper and a single page, is in HTML to PDF Page Setup and Scaling. The full list of options is in HTML to PDF Converter Options.

var converter = new HtmlToPdfConverter();

// repeat <thead> and <tfoot> on every page
converter.PdfDocumentOptions.RepeatTableHeaderFooter = true;

// render with the print stylesheet instead of the screen one
converter.MediaType = "print";

byte[] pdf = converter.ConvertUrl(url);

<!-- start a new page before this element -->
<h2 style="page-break-before: always">Chapter 2</h2>

<!-- keep a block on one page -->
<table style="page-break-inside: avoid">
  <thead><tr><th>Item</th><th>Amount</th></tr></thead>
  <tbody> ... </tbody>
</table>

The page-break-before, page-break-after and page-break-inside properties work as in Chrome's print preview, along with the newer break-before and break-inside properties. Details and a runnable sample: Insert Page Breaks in PDF Using CSS, Avoid Page Break Inside Elements and Repeat HTML Table Header and Footer.

var converter = new HtmlToPdfConverter();

// accessible (PDF/UA-1) and archivable (PDF/A-2b) in one document
converter.PdfDocumentOptions.PdfStandard = PdfStandard.PdfUa1PdfA2b;

// other values: PdfUa1, PdfUa2, PdfA2a, PdfA3b, PdfA4, PdfUa2PdfA4 ...

converter.PdfDocumentInfo.Title = "Annual report 2026";

byte[] pdf = converter.ConvertUrl(url);

The HTML has to be well structured for the result to pass: one h1, headings in order, alt on images, a lang attribute on the root element. The supported standards and combinations are listed, with what each requires from the HTML, in Create PDF/UA and PDF/A Compliant Documents. You can also generate a PDF/UA or PDF/A document from your own HTML in the online demo and run it through veraPDF or PAC yourself.

var converter = new HtmlToPdfConverter();

// collect the position of every invoice line and of the signature box
converter.HtmlElementsInfoSelector = ".line-item, #signature";

byte[] pdf = converter.ConvertUrl(url);

foreach (HtmlElementInfo element in converter.HtmlElementsInfo.Elements)
{
    // one rectangle per page the element appears on
    foreach (PdfRenderedRectangle rect in element.RenderedRectangles)
    {
        Console.WriteLine($"{element.TagName}#{element.Id} page {rect.PageNumber}: " +
            $"{rect.Bounds.X}, {rect.Bounds.Y}, {rect.Bounds.Width} x {rect.Bounds.Height} pt");
    }
}

Each HtmlElementInfo carries the tag name, id, CSS class and text of the element; the collection can also be searched with FindById, FindByClass and FindByTagName. With the page and the rectangle in hand, the PDF editor from the Core component adds whatever the layout needs at exactly that spot. What developers use it for:

The documentation sample highlights every selected element with a colored border, which is the quickest way to see what the converter reports: Retrieve HTML Element Positions in PDF; the same page in the online demo runs it on your own HTML.