title: Pay to 3rd Party PayPal account from website, and confirm success
body: <p><strong>Question:</strong></p>
  
  <p>How can I have a visitor to my site pay to a 3rd party PayPal account (one I do not have access to) and have PayPal return the visitor to my site, confirming that the payment was a success (while requiring no special setup or confidential information from the 3rd party account)?</p>
  
  <p><strong>Details:</strong></p>
  
  <p>My company provides a service to clients of other organizations, however, we collect payment directly from those organizations (and not from their clients). In our particular case, if the organization's client opts to use our service, they will pay the organization they are part of (and not us) - the entirety of their payment goes to the 3rd party organization (the value of the payment may vary, but it will always be billed as a single item). The only information we need from this transaction is: the ID of the client (a value from our database), and some type of verifiable confirmation (ideally, a dollar value paid).</p>
  
  <p>The flow is as follows:</p>
  
  <ol>
  <li>Our site </li>
  <li>redirect to 3rd party PayPal</li>
  <li>return to our site with confirmation </li>
  <li>Authorize transaction and enable service 
  <ul>
  <li>e.g. thank you page with Next button</li>
  <li>payment needs to be authorized before going to next page</li>
  </ul></li>
  </ol>
  
  <p>We would like to implement this in such a way that the 3rd party organization does not need to set up anything additional in their PayPal account, and does not need to share confidential information with us (ideally, they should only need to share their PayPal email address).</p>
  
  <p>Currently, we are exploring using the following:</p>
  
  <ol>
  <li>Buy Now button</li>
  <li>Set the notify_url field on the form</li>
  <li>Setup an IPN listener on our server that will process (and verify) the transaction</li>
  </ol>
  
  <p>The problems are two fold:</p>
  
  <ol>
  <li>We have been unable to confirm that this implementation would not require the 3rd party
  organization to setup anything in their PayPal account (e.g. they
  don't need to setup IPN, since we are using a per transaction URL
  and they don't need to share their API key). </li>
  <li>IPN is asynchronous - so we will not receive the notification as part of the transaction flow (which complicates things, but if no better option exists, we
  can make it work). Is there any synchronous approach that would
  notify us of a successful transaction without requiring additional
  credentials (e.g. PDT requires an identity token so does not appear
  to be an option for us).</li>
  </ol>
  
  <p>If there are any better ways to approach this problem, suggestions would be appreciated.</p>