cdnjs is a free distributed JS library delivery service.
Cloudflare Browser Insights is a tool that measures the performance of websites from the perspective of users.
Cloudflare is a web-infrastructure and website-security company, providing content-delivery-network services, DDoS mitigation, Internet security, and distributed domain-name-server services.
Facebook pixel is an analytics tool that allows you to measure the effectiveness of your advertising.
Google Analytics is a free web analytics service that tracks and reports website traffic.
Heroku is a cloud platform as a service (PaaS) supporting several programming languages.
HTTP Strict Transport Security (HSTS) informs browsers that the site should only be accessed using HTTPS.
Mailchimp is a marketing automation platform and email marketing service.
RackCache is a quick drop-in component to enable HTTP caching for Rack-based applications.
Ruby on Rails is a server-side web application framework written in Ruby under the MIT License.
Twitter is a 'microblogging' system that allows you to send and receive short posts called tweets.