Apache is a free and open-source cross-platform web server software.
Google Analytics is a free web analytics service that tracks and reports website traffic.
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.
Zendesk is a cloud-based help desk management solution offering customizable tools to build customer service portal, knowledge base and online communities.