HTML to PDF in under a millisecond.

// Markdown to PDF, styled like a GitHub README
byte[] pdf = MarkdownToPdf.Convert(File.ReadAllText("README.md"));

// Markdown to HTML: a body fragment, or a complete page with the stylesheet
string fragment = MarkdownToHtml.Convert("# Hello\n\n*World*");
string page = MarkdownToHtml.ConvertDocument(markdown);

var options = new PdfOptions
{
    PageSize = PageSize.Letter.Landscape,
    Margins = PageMargins.FromMillimeters(20, 15, 20, 15),
    BaseDirectory = "/var/app/templates",       // where relative images and stylesheets come from
    FooterText = "Page {page} of {pages}",
    Title = "Invoice 42", Author = "Accounts",
    MaxPages = 1000,
};
byte[] pdf = HtmlToPdf.Convert(html, options);

var options = new PdfOptions();
options.Fonts.AddFile("fonts/OpenSans-Regular.ttf")
             .AddFile("fonts/OpenSans-Bold.ttf");   // only the glyphs you use are embedded

byte[] pdf = HtmlToPdf.Convert(
    "<p style=\"font-family: 'Open Sans'\">Łódź, Ελλάδα, Москва</p>", options);

var archived = new PdfOptions { Conformance = PdfConformance.PdfA2b };

var secret = new PdfOptions
{
    Watermark = new PdfWatermark { Text = "CONFIDENTIAL", Opacity = 0.25f },
    Security = new PdfSecurity { UserPassword = "1234", Permissions = PdfPermissions.Print },
};

var eInvoice = new PdfOptions { EInvoice = new PdfEInvoice(File.ReadAllBytes("invoice.xml")) };

// Tagged for screen readers, and both PDF/UA-1 and PDF/A
var accessible = new PdfOptions { Accessibility = PdfAccessibility.PdfUA1, Conformance = PdfConformance.PdfA2b };

// Peppol or OIOUBL: the PDF travels inside the UBL invoice XML
byte[] xml = UblInvoice.AttachPdf(File.ReadAllBytes("invoice.xml"), pdf, "INV-1001.pdf");

byte[] merged = PdfMerger.Merge(invoicePdf, termsPdf, attachmentPdf);

// Streams in and out: one input in memory at a time
await PdfMerger.MergeAsync(uploads.Select(f => f.OpenReadStream()), response.Body);

// Or add PDFs as they arrive, and skip the ones that are missing
var merger = new StreamingPdfMerger(response.Body);
foreach (var path in paths)
    if (await storage.DownloadAsync(path) is { Length: > 0 } pdf) await merger.AddAsync(pdf);
await merger.CompleteAsync();

// Every page as PNG bytes, rendered in parallel
byte[][] pages = PdfToImage.Convert(pdfBytes, new ImageOptions { Dpi = 150 });

// report.pdf -> out/report-1.png, out/report-2.png, ...
PdfToImage.ConvertFile("report.pdf", "out");