cdnjs is a free distributed JS library delivery service.
Cloudflare is a web-infrastructure and website-security company, providing content-delivery-network services, DDoS mitigation, Internet security, and distributed domain-name-server services.
Cloud CDN uses Google's global edge network to serve content closer to users.
HTTP Strict Transport Security (HSTS) informs browsers that the site should only be accessed using HTTPS.
Zendesk is a cloud-based help desk management solution offering customizable tools to build customer service portal, knowledge base and online communities.