PHPBuilder.com has posted a tutorial showing you how to interact with the PayPal API via your PHP application using their own PHP-SDK.

PayPal recently introduced a new RESTful API that is more convenient and more powerful than the previous version. In this article, I will show you how to integrate your PHP application with the new PayPal API.

They start with a summary of the PayPal API and how to get the SDK loaded and ready to use (either through Composer or manually). The tutorial walks you through the authorization process (OAuth) and the code you'll need to make it happen. They also show you how to create transaction (including currency type and description) after the items have been submitted. There's also some code showing you how to get the current status of the payment once it has been submitted.

On the SitePoint PHP blog there's a new tutorial today showing you how to setup a user login through PayPal that lets users authenticate for your application through PayPal's systems.

Curiosity is one of the most important traits in our job. The other day, I found myself exploring PayPal documentation to find something interesting to learn (and share). After a while I stumbled upon the Log In with PayPal tool. With the “Log In with PayPal” tool, your users can authenticate into your application using PayPal. It’s the same procedure we already know for Facebook, or maybe Twitter and GitHub. Using this type of authentication is recommended if you want to integrate it with an e-commerce website, but you can use it in every situation and application that requires a user account or membership.

He starts by answering the "why use it" question, suggesting that it adheres to one of the main goals of good, secure authentication systems - simplicity. He then shares an overview of how the process flow works including a graphic outlining each piece involved and what kinds of data is transmitted at each step. He then walks you through the full process of setting up a PayPal application on your account and using the Httpful library (installed via Composer) to connect to their API. He includes the code you'll need to include in your application to provide the link to PayPal for the login and the page it will return to once the process is complete.

NetTuts.com has a new tutorial posted today about processing payments with PayPal using their "Payments Pro" API and a handy library that makes it pretty simple.

While one of its most popular features is the ability to simply sign in to your PayPal account to submit payments, merchants using PayPal can also accept credit cards directly just like a traditional merchant account solution would provide. PayPal calls this solution Payments Pro, and I’m going to show you exactly how you can process credit cards directly with PayPal’s API using their Payments Pro web service API’s.

They've broken it up into the different steps including:

• Setting up the configuration
• Creating a first API request
• Sending the HTTP request to the PayPal API (via curl)
• Parsing the response

In a recent post Eran Galperin takes a look at the PayPal API and breaks it down into smaller, easy to digest chunks to show you how to you can implement it in your application. Be warned, though - he mentions that it's the "among the worst API he's ever had to deal with" for several reasons.

PayPal is the most popular platform for receiving online payments. The relative ease of opening a PayPal account and receiving payments compared to opening a merchant account for a traditional payment gateway is the number one reason, and another is the comprehensive API they provide for their payment services. [...] There doesn't seem to be any better alternatives currently, so hopefully this guide will help ease the pain for some of you out there taking your lumps working the API into your applications.

Eran starts with a look at some of the different payment options, express, direct, recurring and mass, and what they're good for. From there, it's off to the code with his tool of choice being curl to make it simpler to make requests with headers, content and fetch the response message. He's put together a little custom function to make it easier to reuse. As an example, he shows how to make an Express Checkout request by grabbing a token and redirecting to the PayPal site for handling.

On the 9Lessons blog today Srinivas Tamadashows you how to create a simple PayPal interface between their API and your site to make accepting payments easier.

I received a tutorial requests from my reader that asked to me how to implement payment gateway system with Paypal API. In this post I want to explain how to work with Paypal Sandbox test accounts for payment system development and sending arguments while click buy now button. It’s simple and very easy to integrate in your web projects.

He includes the SQL to create a basic database for storing product and sales information (as well as a bit of user data linked to them) as well as instructions on creating the accounts you'll need on the PayPal side. The script creates a form that takes the payment information and pushes it to a script on the PayPal side for validation and charging.

In a recent post Matt Williams shares how to integrate your application with the PayPal IPN payment gateway service.

PayPal has a huge API reference to integrate it's services into any website. But from personal experience I found that the theory is far more simple than the practice. There are various methods to implement PayPal's services including Soap webservices with 'Express Checkout' and 'Website Payment Pro'. This tutorial will focus on 'Website Payment Pro' and the 'IPN' event listener.

He shows how to send the information as a POST request in one of two ways - as a standard form submission kind of POST and from a script opening a direct socket to the PayPal server and sending over a well-formed request.

On NETTUTS.com a recent tutorial has been posted about the integration of your PHP application with PayPal's Instant Payment Notification system.

Today we are going to combine Paypal with PHP to allow for the easy processing of payments on your website.

You'll need a Premier PayPal Account to get it all working as well as already have a server with a working PHP installation (there's no setup and install for that in this tutorial). There's ten different steps in the process and screenshots and code are provided the whole way:

• Creating a PayPal Account
• Enable IPN
• Building a Simple HTML Page
• Building a PayPal Button
• Writing ipn.php
• Creating the Database
• Account Creation
• Emailing the Login Credentials
• Invalid Payment Email
• User Login

Juozas Kaziukenas points out a new class in his latest blog post that can be used to make secure connections over to PayPal (encrypted) using their Encrypted Website Payment method.

In my situation, PayPal is only used to pay for orders - cart and order setup is done in our shop, so I do not want to have additional problems with users changing orders numbers, amount to be paid, etc. [...] Only PayPal knows how to decrypt it, because it uses public key encryption technology (you need to upload your certificate in PayPal account).

Some sample usage code is included as is a link to the class itself. His example takes a payment transaction including the item name, amount and currency type and sends it off to the PayPal servers in a connection protected by certificates.

Chris Hartjes in looking for a plugin to integrate a CakePHP application with PayPal, came across an interesting tip from a fellow CakePHP developer - a plugin server.

John Anderson (aka psychic, the lead on the CakePHP Cookbook project) mentioned that he had a plugin I could use. He also provided a link to an experimental CakePHP plugin server he’s setup and asked people to play around with. That PayPal plugin was one of the ones being offered.

This PayPal plugin is one of many housed on the server. There's also a client script that can be used on the command line to fetch and upload plugins to and from the site.

NETTUTS.com has posted their top ten list of some of the largest milestones in web development - one of which is the release of PHP.

Some believe the progression of the great World Wide Web to be a travesty, others a godsend. Regardless, the Internet has evolved over the past few decades, and is in many ways better for the web developer. New technologies have come about that have made web development much easier to get started in, and ultimately more fun.

Here's a few from their list:

• Linus Torvalds Creates the Linux Kernel
• The Open Source Movement Officially Starts
• PayPal is Founded
• Firefox is Released
• and, of course, PHP is Released by Rasmus Lerdorf