Printing Server

A lightweight HTTP print server that runs as a Windows service and accepts localhost API calls from a browser to send files to system printers.

Prerequisites

• Windows 10/11 (x64)
• .NET 10 SDK (for building)
• Inno Setup (for creating the installer manually)

Supported File Types

Type	Content-Type	Print Method
PDF	application/pdf	SumatraPDF (Session 0 safe)
PNG	image/png	GDI+ PrintDocument
JPEG	image/jpeg	GDI+ PrintDocument
BMP	image/bmp	GDI+ PrintDocument
GIF	image/gif	GDI+ PrintDocument
TIFF	image/tiff	GDI+ PrintDocument
Plain text	text/plain	GDI+ PrintDocument (Consolas 10pt, paginated)
ZPL	application/vnd.zebra.zpl or text/x-zpl	Raw print via Windows spooler
Word	application/msword, application/vnd.openxmlformats-officedocument.wordprocessingml.document	Shell verb (interactive mode only)
Excel	application/vnd.ms-excel, application/vnd.openxmlformats-officedocument.spreadsheetml.sheet	Shell verb (interactive mode only)

Office documents (DOC/DOCX/XLS/XLSX) are only supported when running interactively (not as a Windows service). Convert to PDF first when running as a service.

CI/CD

The project includes a GitHub Actions workflow (.github/workflows/build.yml) that runs on every push and PR to main. It restores, builds, runs tests, publishes, and compiles the Inno Setup installer. The resulting PrintingServerSetup.exe is uploaded as a build artifact.

SumatraPDF portable is committed to the repo at PrintingServer/tools/SumatraPDF.exe and bundled automatically during publish.

Build and Install

From CI (recommended)

1. Download PrintingServerSetup.exe from the latest GitHub Actions run artifacts
2. Run the installer as administrator on the target machine

The installer will:

• Copy files to Program Files\PrintingServer
• Register and start a Windows service named PrintingServer
• The service starts automatically on boot

Manual build

1. Publish

dotnet publish PrintingServer/PrintingServer.csproj -c Release -o PrintingServer/bin/publish

2. Create installer

Compile installer.iss with Inno Setup. The output installer will be in installer_output/PrintingServerSetup.exe.

3. Run the installer

Run PrintingServerSetup.exe as administrator.

Configuration

Edit appsettings.json in the install directory to change the port (default 5123):

{
  "PrintingServer": {
    "Port": 5123
  }
}

Restart the service after changing configuration:

sc stop PrintingServer
sc start PrintingServer

API

Health check

GET http://localhost:5123/health

{ "status": "ok" }

List printers

GET http://localhost:5123/printers

{
  "defaultPrinter": "HP LaserJet Pro",
  "printers": ["HP LaserJet Pro", "Microsoft Print to PDF", "Zebra ZD420"]
}

Print a file

POST http://localhost:5123/print?printer=HP%20LaserJet%20Pro&copies=2
Content-Type: application/pdf

<file bytes>

Parameter	Required	Description
printer	No	Printer name. Uses default printer if omitted.
copies	No	Number of copies. Defaults to 1.

Success:

{ "message": "Print job submitted.", "printer": "HP LaserJet Pro" }

Error:

{ "error": "Printer 'FakePrinter' is not valid." }

JavaScript examples

// Print a PDF (2 copies)
await fetch("http://localhost:5123/print?printer=HP%20LaserJet%20Pro&copies=2", {
  method: "POST",
  headers: { "Content-Type": "application/pdf" },
  body: pdfBlob
});

// Print a PNG
await fetch("http://localhost:5123/print?printer=HP%20LaserJet%20Pro&copies=1", {
  method: "POST",
  headers: { "Content-Type": "image/png" },
  body: pngBlob
});

// Print a JPEG
await fetch("http://localhost:5123/print?printer=HP%20LaserJet%20Pro&copies=1", {
  method: "POST",
  headers: { "Content-Type": "image/jpeg" },
  body: jpegBlob
});

// Print a ZPL label (3 copies)
await fetch("http://localhost:5123/print?printer=Zebra%20ZD420&copies=3", {
  method: "POST",
  headers: { "Content-Type": "text/x-zpl" },
  body: "^XA^FO50,50^ADN,36,20^FDShipping Label^FS^XZ"
});

// Print plain text
await fetch("http://localhost:5123/print?printer=HP%20LaserJet%20Pro&copies=1", {
  method: "POST",
  headers: { "Content-Type": "text/plain" },
  body: "Pick List\n---------\nItem 1: Widget A  x3\nItem 2: Widget B  x1"
});

// Print a Word document (interactive mode only)
await fetch("http://localhost:5123/print?printer=HP%20LaserJet%20Pro&copies=1", {
  method: "POST",
  headers: { "Content-Type": "application/vnd.openxmlformats-officedocument.wordprocessingml.document" },
  body: docxBlob
});

// Print an Excel spreadsheet (interactive mode only)
await fetch("http://localhost:5123/print?printer=HP%20LaserJet%20Pro&copies=1", {
  method: "POST",
  headers: { "Content-Type": "application/vnd.openxmlformats-officedocument.spreadsheetml.sheet" },
  body: xlsxBlob
});

Running Tests

dotnet test

Uninstall

Run the uninstaller from Add/Remove Programs. It stops and removes the Windows service, then deletes the installed files.