PayPal/IPN

Overview

Instant Payment Notification (IPN) is one of two methods by which a web site may retrieve payment information from PayPal in real-time, i.e. immediately after a payment is completed. The other method is Payment Data Transfer (PDT).

IPN is somewhat more reliable than PDT in that PayPal's server contacts the merchant's server directly to transmit transaction data as soon as the transaction has occurred, rather than depending on the customer's browser to convey the data.

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Example

Sample data passed back to the merchant's server using IPN (using the PayPal Sandbox, not a real transaction), as collected by SpecialLogPost:

HTML form code

<xml> <form action="https://www.sandbox.paypal.com/cgi-bin/webscr" method="post"> <input type="hidden" name="cmd" value="_s-xclick"> <input type="hidden" name="hosted_button_id" value="14406"> <input type="hidden" name="custom" value="UserNameWouldGoHere"> <input type="hidden" name="invoice" value="InvoiceFieldGoesHere"> <input type="hidden" name="notify_url" value="http://wiki.vbz.net/Special:LogPost"> <input type="hidden" name="return" value="http://test.vbz.net/cgi-bin/runpl"> <input type="image" src="https://www.sandbox.paypal.com/en_US/i/btn/btn_subscribeCC_LG.gif"

border="0" name="submit" alt="">

<img alt="" border="0" src="https://www.sandbox.paypal.com/en_US/i/scr/pixel.gif" width="1" height="1"> </form> </xml>

IPN POSTed data

2009-01-01 21:58:16
	REQUEST_METHOD	POST
	HTTP_USER_AGENT	
	REMOTE_ADDR	216.113.191.33
		transaction_subject	
		payment_date	18:58:14 Jan 01, 2009 PST
		txn_type	subscr_payment
		subscr_id	S-5G6357170N2927728
		last_name	User
		residence_country	US
		item_name	Full Site Access - one year
		payment_gross	49.00
		mc_currency	USD
		business	paypal_1230320215_biz@hypertwins.org
		payment_type	instant
		protection_eligibility	Ineligible
		verify_sign	AxvQhTcd4JBdIIpB5MztE755SMD7AMz0sJLKKvdDiqzSP8TKRFoLHttM
		payer_status	verified
		test_ipn	1
		payer_email	paypal_1230659178_per@hypertwins.org
		txn_id	17R310755W630331M
		receiver_email	paypal_1230320215_biz@hypertwins.org
		first_name	Test
		invoice	InvoiceFieldGoesHere
		payer_id	9AAMA7CUQ8TUN
		receiver_id	YCRD6GWFSUZ5L
		payment_status	Completed
		payment_fee	1.72
		mc_fee	1.72
		btn_id	14406
		mc_gross	49.00
		charset	windows-1252
		notify_version	2.6
2009-01-01 21:58:16
	REQUEST_METHOD	POST
	HTTP_USER_AGENT	
	REMOTE_ADDR	216.113.191.33
		txn_type	subscr_signup
		subscr_id	S-5G6357170N2927728
		last_name	User
		residence_country	US
		mc_currency	USD
		item_name	Full Site Access - one year
		business	paypal_1230320215_biz@hypertwins.org
		amount3	49.00
		recurring	1
		verify_sign	AdXmlE88KERMphmdMG4e.jeWGlkRAcUYzJVdMfWdteAAmuWxx9bpnguV
		payer_status	verified
		test_ipn	1
		payer_email	paypal_1230659178_per@hypertwins.org
		first_name	Test
		receiver_email	paypal_1230320215_biz@hypertwins.org
		payer_id	9AAMA7CUQ8TUN
		invoice	InvoiceFieldGoesHere
		reattempt	1
		subscr_date	18:58:12 Jan 01, 2009 PST
		btn_id	14406
		charset	windows-1252
		notify_version	2.6
		period3	1 Y
		mc_amount3	49.00

Note that IPN returns the invoice data but not the custom data.