AddThis is a social bookmarking service that can be integrated into a website with the use of a web widget.
Websites that have a shopping cart or checkout page, either using a known ecommerce platform or a custom solution.
Google Tag Manager is a tag management system (TMS) that allows you to quickly and easily update measurement codes and related code fragments collectively known as tags on your website or mobile app.
Prototype is a JavaScript Framework that aims to ease development of web applications.