Express Checkout Express Checkout Integration Guide (PDF, HTML) Learn the basics of how to integrate Express Checkout with your website. See where Express Checkout goes on your site. Learn where your site needs to call the API. Express Checkout Advanced Features Guide (PDF, HTML) Learn about advanced features that enhance your integration of Express Checkout, such as customizing PayPal payment pages to match the look of your website and updating shipping charges as buyers make changes on the PayPal review page. Digital Goods Integration Guide - Express Checkout Edition (PDF, HTML) Learn how to streamline the checkout process for buyers of digital goods. Buyers can conveniently purchase digital goods during checkout with a minimum of clicks without leaving your website or interrupting their online activities. Preparing for the New Updated PayPal Checkout Experience (PDF) Learn about the new updated PayPal Checkout experience for Express Checkout. This guide provides the programming variables to customize the new updated checkout user interface. Name-Value Pair API Developer Guide and Reference (PDF, HTML) Learn how to use the Name-Value Pair API. Includes code samples, an API reference, information on SDKs, and web samples. SOAP API Developer Reference (PDF, HTML) Programmers familiar with SOAP (Simple Object Access Protocol) can learn more about the PayPal SOAP API. Sandbox User Guide (PDF , HTML) Learn how to test your PayPal-based applications before using them in production with the Sandbox – PayPal's virtual test environment. Instant Payment Notification Guide (PDF, HTML) Instant Payment Notification (IPN) is a message service that notifies you of events related to PayPal transactions. You can use IPN to automate back-office and administrative functions. Express Checkout User Interface Standards (PDF) Express Checkout User Interface Standards details the requirements and best practices for placing PayPal graphic images on your website. It also explains how buyers who pay with PayPal will experience checkout on your website, and how you can modify that buyer experience depending on your needs. Adaptive Payments Adaptive Payments Developer Guide (PDF, HTML) The Adaptive Payments API enables you to send money in many different scenarios, from simple to complex. For example, you might build a small send money application for a social networking site or a robust payroll system. Adaptive Accounts Adaptive Accounts Developer Guide (PDF, HTML) The Adaptive Accounts API lets you build applications that create PayPal accounts and handle account management. Permissions Permissions Service Guide (PDF, HTML) The Permissions Service enables you to obtain permission to execute PayPal API operations on behalf of PayPal account holders. Merchant Setup and Administration Guide Merchant Setup and Administration Guide (PDF, HTML) Learn how merchants set up and administer their accounts, including setting their credit card statement names, blocking certain kinds of payment, adding users to their accounts, managing multiple currency balances, creating custom payment pages, getting contact numbers from payers, and working with transaction history. Website Payments Standard Website Payments Standard Integration Guide (PDF, HTML) Learn how to use HTML forms and get paid through PayPal. Preparing for the New Updated PayPal Checkout Experience (PDF) Learn about the new updated PayPal Checkout experience for Website Payments Standard. This guide provides the programming variables to customize the new updated checkout user interface. NOTE: For Website Payments Standard, the new updated experience applies only to Buy Now and Add to Cart buttons and the Cart Upload command.

Updates: 10th August 2011 The payments.php code (Line 60-64) has been slightly amended to fix the IPN Invalid Response. If you are not receiving the correct response from Paypal ensure that you are using the main test account (Verified Business Account) from your Paypal Sandbox account. Also ensure that you are testing the Paypal IPN Script on an online webserver (Not MAMP, Xampp etc..) as Paypal requires a reachable ‘return url’, ‘cancel url’ and ‘notify url’. The downloadable source code has been updated with the above changes. PayPal is the most popular payment service on the web so being able to integrate your website with PayPal’s Instant Payment Notification Service (IPN) is essential if you need to process payments through your website. There are 3 main parts to the PayPal IPN system. A webpage that initiates a request to PayPal to make a payment. A PHP page on your webserver that PayPal calls to notify you that payment has been made. A webpage that confirms the above payment and continues on to the next phase of your web application, such as a ‘Thank You’ page. Parts 1 and 3 are accessible by customers on your website. Part 2 is only visible to PayPal. The diagram below illustrates the interaction between your customer, PayPal and your website.

Express Checkout Express Checkout Integration Guide (PDF, HTML) Learn the basics of how to integrate Express Checkout with your website. See where Express Checkout goes on your site. Learn where your site needs to call the API. Express Checkout Advanced Features Guide (PDF, HTML) Learn about advanced features that enhance your integration of Express Checkout, such as customizing PayPal payment pages to match the look of your website and updating shipping charges as buyers make changes on the PayPal review page. Digital Goods Integration Guide - Express Checkout Edition (PDF, HTML) Learn how to streamline the checkout process for buyers of digital goods. Buyers can conveniently purchase digital goods during checkout with a minimum of clicks without leaving your website or interrupting their online activities. Preparing for the New Updated PayPal Checkout Experience (PDF) Learn about the new updated PayPal Checkout experience for Express Checkout. This guide provides the programming variables to customize the new updated checkout user interface. Name-Value Pair API Developer Guide and Reference (PDF, HTML) Learn how to use the Name-Value Pair API. Includes code samples, an API reference, information on SDKs, and web samples. SOAP API Developer Reference (PDF, HTML) Programmers familiar with SOAP (Simple Object Access Protocol) can learn more about the PayPal SOAP API. Sandbox User Guide (PDF , HTML) Learn how to test your PayPal-based applications before using them in production with the Sandbox – PayPal's virtual test environment. Instant Payment Notification Guide (PDF, HTML) Instant Payment Notification (IPN) is a message service that notifies you of events related to PayPal transactions. You can use IPN to automate back-office and administrative functions. Express Checkout User Interface Standards (PDF) Express Checkout User Interface Standards details the requirements and best practices for placing PayPal graphic images on your website. It also explains how buyers who pay with PayPal will experience checkout on your website, and how you can modify that buyer experience depending on your needs. Adaptive Payments Adaptive Payments Developer Guide (PDF, HTML) The Adaptive Payments API enables you to send money in many different scenarios, from simple to complex. For example, you might build a small send money application for a social networking site or a robust payroll system. Adaptive Accounts Adaptive Accounts Developer Guide (PDF, HTML) The Adaptive Accounts API lets you build applications that create PayPal accounts and handle account management. Permissions Permissions Service Guide (PDF, HTML) The Permissions Service enables you to obtain permission to execute PayPal API operations on behalf of PayPal account holders. Merchant Setup and Administration Guide Merchant Setup and Administration Guide (PDF, HTML) Learn how merchants set up and administer their accounts, including setting their credit card statement names, blocking certain kinds of payment, adding users to their accounts, managing multiple currency balances, creating custom payment pages, getting contact numbers from payers, and working with transaction history. Website Payments Standard Website Payments Standard Integration Guide (PDF, HTML) Learn how to use HTML forms and get paid through PayPal. Preparing for the New Updated PayPal Checkout Experience (PDF) Learn about the new updated PayPal Checkout experience for Website Payments Standard. This guide provides the programming variables to customize the new updated checkout user interface. NOTE: For Website Payments Standard, the new updated experience applies only to Buy Now and Add to Cart buttons and the Cart Upload command.

Apps and Integration Experts Magento Connect - the world's largest commerce application marketplace with nearly 5,000 extensions to customize your online store*** Per extension PayPal and eBay apps Per app X.commerce Solution Partners – world class solution providers working with existing store fronts to integrate the stand-alone capabilities, services and apps of X.commerce. † Custom Magento Solution Partners - world class system solution providers to help you develop and manage your technology needs. Custom * Please see applicable links for full terms of service for each capability - e.g. standard fees for eBay, PayPal and other providers. ** International products will have similar pricing based on local offerings and currency. *** In 2012, X.commerce will be adding to this marketplace, listing apps built using eBay, PayPal, Milo, Red Laser, Where, Zong technology, providing the leading platform for developers to create extensions and apps that serve all parts of the commerce universe.