Using a framework can help speeding up and improving the application. Find out which framework to learn and how to create your custom framework.
There are quite a lot of existing open source very good solutions for eCommerce purposes currently available in PHP.
PHP ecosystem of open source code from various resources.
Application programming interfaces
How to test and write quality PHP code.
Get your application into production.
Upgrade your PHP.
What is a license and which license should you pick for your open source project.
Asynchronous programming in PHP.