What is it?
Composer is the de facto standard for dependency management in PHP these days. Using Composer, you can install and upgrade both open source and your own private components.
How to support
Jordi Boggiano, lead developer of Composer, runs his own company. One of the products he has released specifically to fund time for his Composer work is Toran Proxy. Toran ensures more stable and faster use of Composer by forming a proxy layer between your server and the repositories used by your project. While Toran Proxy is free for personal use, you can buy yourself a supporter license, or if you have a company you can purchase company licenses.