HTML to PDF on Azure App Service (Linux) in C#

Build it step by step.

1. 1Create the project

   A web project with three packages. The engine package matches the machine that builds the app, so dotnet run works on Windows, and dotnet publish -r linux-x64 packs the Linux engine for App Service. The fonts package covers Chinese, Japanese, Korean and other scripts that the Linux image has no fonts for.

   PdfApp.csproj COPY

   <Project Sdk="Microsoft.NET.Sdk.Web">
   
     <PropertyGroup>
       <TargetFramework>net10.0</TargetFramework>
       <Nullable>enable</Nullable>
       <ImplicitUsings>enable</ImplicitUsings>
     </PropertyGroup>
   
     <!-- the engine for the machine that builds the app; publishing with -r linux-x64 picks Linux,
          which is what App Service on Linux needs. Fonts: the Linux image has none for CJK and other scripts. -->
     <PropertyGroup>
       <_SelectPdfArch>$([System.Runtime.InteropServices.RuntimeInformation]::OSArchitecture.ToString().ToLowerInvariant())</_SelectPdfArch>
       <SelectPdfRid Condition="$([MSBuild]::IsOSPlatform('Windows'))">win-$(_SelectPdfArch)</SelectPdfRid>
       <SelectPdfRid Condition="$([MSBuild]::IsOSPlatform('Linux'))">linux-$(_SelectPdfArch)</SelectPdfRid>
       <SelectPdfRid Condition="$([MSBuild]::IsOSPlatform('OSX'))">osx-$(_SelectPdfArch)</SelectPdfRid>
       <SelectPdfRid Condition="'$(RuntimeIdentifier)' != ''">$(RuntimeIdentifier)</SelectPdfRid>
     </PropertyGroup>
   
     <ItemGroup>
       <PackageReference Include="SelectPdf.Universal" Version="26.5.0" />
       <PackageReference Include="SelectPdf.Universal.Native.$(SelectPdfRid)" Version="26.5.0" />
       <PackageReference Include="SelectPdf.Universal.Fonts" Version="26.5.0" />
     </ItemGroup>
   
   </Project>

2. 2A minimal web app

   Program.cs · lines 1–7 COPY

   using SelectPdf.Universal;
   
   var builder = WebApplication.CreateBuilder(args);
   var app = builder.Build();
   
   // GET /report.pdf: a PDF made on the server, with text in Latin, Greek and CJK scripts
   app.MapGet("/report.pdf", async (CancellationToken cancel) =>

   One endpoint, GET /report.pdf. The CancellationToken is the request's.

3. 3HTML in three scripts

   Program.cs · lines 9–13 COPY

       string html = """
           <h1>Quarterly report</h1>
           <p>English · Deutsch · Ελληνικά</p>
           <p>日本語 · 中文 · 한국어</p>
           """;

   Latin, Greek and CJK text. The CJK line needs SelectPdf.Universal.Fonts on Linux; without it, those characters would print as empty boxes.

4. 4Convert and return the PDF

   Program.cs · lines 15–23 COPY

       HtmlToPdf converter = new HtmlToPdf();
       PdfDocument doc = await converter.ConvertHtmlStringAsync(html, cancel);
       byte[] pdf = doc.Save();
       doc.Close();
   
       return Results.File(pdf, "application/pdf");
   });
   
   app.Run();

   ConvertHtmlStringAsync renders the HTML and Save() returns the bytes. Without a file name, Results.File lets the browser show the PDF.

5. 5Run it

   terminal COPY

   dotnet run
   
   # then open the address dotnet run prints, followed by /report.pdf

   The request returns report.pdf. Without a license key, every page carries a trial watermark; set GlobalProperties.LicenseKey before the first conversion to remove it.

The complete Program.cs.

This is the exact file our samples pipeline compiled and ran on Azure App Service Linux .NET 10 image, x64 and Linux ARM64 and Linux x64 and macOS ARM64 and Windows x64 to produce the output on this page.

using SelectPdf.Universal;

var builder = WebApplication.CreateBuilder(args);
var app = builder.Build();

// GET /report.pdf: a PDF made on the server, with text in Latin, Greek and CJK scripts
app.MapGet("/report.pdf", async (CancellationToken cancel) =>
{
    string html = """
        <h1>Quarterly report</h1>
        <p>English · Deutsch · Ελληνικά</p>
        <p>日本語 · 中文 · 한국어</p>
        """;

    HtmlToPdf converter = new HtmlToPdf();
    PdfDocument doc = await converter.ConvertHtmlStringAsync(html, cancel);
    byte[] pdf = doc.Save();
    doc.Close();

    return Results.File(pdf, "application/pdf");
});

app.Run();

Open the project on GitHub → this program and the variations below, ready to dotnet run

Deploy it.

Create a Linux plan and a .NET 10 web app, turn on Always On, and deploy the published app as a zip. Replace <app-name> with a name of your own; on Windows, create the zip with Compress-Archive publish\* app.zip.

az login
az group create --name selectpdf-rg --location westeurope
az appservice plan create --resource-group selectpdf-rg --name selectpdf-plan --sku P1v3 --is-linux
az webapp create --resource-group selectpdf-rg --plan selectpdf-plan --name <app-name> --runtime "DOTNETCORE:10.0"
az webapp config set --resource-group selectpdf-rg --name <app-name> --always-on true

dotnet publish -c Release -r linux-x64 --self-contained false -o publish
cd publish && zip -r ../app.zip . && cd ..
az webapp deploy --resource-group selectpdf-rg --name <app-name> --src-path app.zip --type zip

# then open https://<app-name>.azurewebsites.net/report.pdf

These steps, with the Windows variants, are in the documentation: selectpdf.com/pdf-library/html/Azure-App-Service.htm.

The PDF it produces.

Common problems and fixes.

Good to know.

• App Service runs SelectPdf on Windows and Linux on the Basic plan or above, with the complete feature set; Free and Shared plans are not supported. Source
• The Linux image has no fonts for Chinese, Japanese and Korean, and a code deployment cannot install any, so reference SelectPdf.Universal.Fonts. Source
• On Premium v3 a warm Linux instance converts selectpdf.com in about 1.3 seconds; Basic and Standard take about four times longer. Source
• Always On keeps the application loaded while idle, so the engine stays warm. Source