KwickPython

What It Does

KwickPython is a tiny Python CGI script that bridges the gap between your web application and local printers. It runs as a local HTTP server on port 9100 and accepts AJAX requests from your webpage — enabling silent, direct printing to any attached printer.

JavaScript API

Get List of Printers

$.ajax({
  url: 'http://127.0.0.1:9100/htbin/kp.py',
  success: function(printers) {
    console.log(printers);  // JSON object of all printers
  }
});

Check Printer Status

$.ajax({
  url: 'http://127.0.0.1:9100/htbin/kp.py',
  data: { p: 'Kitchen_Printer' },
  success: function(status) {
    console.log(status);  // "Kitchen_Printer Ready"
  }
});

Send Print Job

$.ajax({
  url: 'http://127.0.0.1:9100/htbin/kp.py',
  data: {
    p: 'Receipt_Printer',
    d: btoa(rawEscPosData)  // Base64 encoded ESC/POS data
  },
  success: function(bytes) {
    console.log(bytes + ' bytes sent');
  }
});

Setup (5 Minutes)

Requirements: Windows + Python 3 + pywin32

1. Create directory: C:\KwickPython\htbin
2. Save kp.py to C:\KwickPython\htbin\kp.py
3. Start the server:

# Start KwickPython on port 9100
cd C:\KwickPython
python -m http.server --cgi 9100

Your web app can now print to any local printer via AJAX calls to http://127.0.0.1:9100/htbin/kp.py

Port Configuration

Port 9100 is the standard raw printing port. You can use any port — just update both the server command and your AJAX URLs to match:

# Use a custom port
python -m http.server --cgi 1234

Security

By default, KwickPython accepts requests from any origin (Access-Control-Allow-Origin: *). For production, lock it down to your domain:

# In kp.py, change:
print('Access-Control-Allow-Origin: *')
# To:
print('Access-Control-Allow-Origin: https://yourdomain.com')

Full Source Code

The entire script — under 50 lines:

# KwickPython [FREE TO USE FOR ANY PROJECT, NO WARRANTY]
# Link back to https://kwickpos.com if it works for you
import cgi, os, sys, win32print, pywintypes

print("Access-Control-Allow-Origin: *")
print("Content-Type: text/plain\n")

form = cgi.FieldStorage()
p = form.getvalue('p')

if p:
    data = form.getvalue('data')
    if data:
        import base64
        raw_data = base64.b64decode(data)
        if raw_data:
            h = win32print.OpenPrinter(p)
            hJob = win32print.StartDocPrinter(h, 1,
                ("KwickPOS Ticket", None, "RAW"))
            win32print.StartPagePrinter(h)
            b = win32print.WritePrinter(h, raw_data)
            win32print.EndPagePrinter(h)
            win32print.EndDocPrinter(h)
            win32print.ClosePrinter(h)
            print(b)
            sys.exit()
    else:
        try:
            h = win32print.OpenPrinter(p)
            d = win32print.GetPrinter(h, 2)
            win32print.ClosePrinter(h)
            a = d['Attributes']
            hex_val = hex(a)
            if hex_val[-3] == '6':
                print(p + ' Offline')
                sys.exit()
            s = d['Status']
            if s == 1:
                print(p + ' Paused')
                sys.exit()
            print(p + ' Ready')
        except pywintypes.error:
            print(p + ' No Such Printer')
else:
    import json
    p = {}
    lst = win32print.EnumPrinters(2)
    for f, d, n, c in lst:
        p[n] = {'d': d, 'c': c}
    print(json.dumps(p))