Sell Digital Downloads with Google Scripts

You can set up your own digital shop on the Internet with the help of PayPal and Google Scripts. You upload your file on Google Drive, the buyer makes a purchase through PayPal and Google Apps Script will deliver the file to the buyer through Gmail.

See: Sell Digital Products Online

/* PayPal Shop with Apps Script */
/* Written by Amit Agarwal - ctrlq.org */


/* Add the PayPal Item Ids and Google Drive Files names here */
PAYPAL = [
  ["product-001", "useful-websites-book.pdf"],
  ["product-002", "linux-training-course.mp4"],
  ["product-003", "labnol-audio-book.mp3"],
  ["product-004", "presentation-template.ppt"]
];

/* The script will scan your Gmail inbox every 5 minutes for PayPal emails */
function PayPal() {
  ScriptApp.newTrigger("myShop").timeBased().everyMinutes(5).create();
}

function myShop() {
  
  var file, size, files, threads;
  
  for (var p in PAYPAL) {
    
    threads = GmailApp.search("is:unread from:paypal " + PAYPAL[p][0]);
    
    if (threads.length > 0) {
      
      /* Find the file in Google Drive */
      files = DriveApp.searchFiles('title contains "' + PAYPAL[p][1] + '"');
      
      if (files.hasNext()) {
        
        file = files.next();
        size = file.getSize()/(1024*1024);
        
        for (var i=0; i<threads.length; i++) {   
          
          /* The PayPal transaction emails container the buyer's email in the Reply-To field */
          var buyer   = threads[i].getMessages()[0].getReplyTo();
          var subject = "Thank you for your purchase";
          var body    = "Please download the file using the link below.\n\n";
          
          /* Check the size of the Google Drive file (in MB) */
          if (size > 20) {
            file.addViewer(buyer); /* For big files, share the file with the buyer */
            GmailApp.sendEmail(buyer, subject, body + file.getUrl());
          } else {
            /* Else attach the file in the email message itself */
            GmailApp.sendEmail(buyer, subject, body, {attachments: file.getBlob()});
          }
          
          /* Move the PayPal email to Archive and Mark it as Read */
          threads[i].markRead().moveToArchive();
        }
      }
    }
  }
}