Khan Academy Payment Storing Services

To donate to Khan Academy
https://www.khanacademy.org/donate?amount=3&week=23&treatment=11&utm_source=Sailthru&utm_medium=email&utm_campaign=Blast%204:%20Users%20%28Forward%29&utm_term=all_users_12_3_15

Khan Academy uses Stripe to accept payment.
https://stripe.com/checkout/info