Amazon S3 or Amazon Simple Storage Service is a service offered by Amazon Web Services (AWS) that provides object storage through a web service interface.
Calendly is an app for scheduling appointments, meetings, and events.
Google Analytics is a free web analytics service that tracks and reports website traffic.
Mailchimp is a marketing automation platform and email marketing service.
Nginx is a web server that can also be used as a reverse proxy, load balancer, mail proxy and HTTP cache.
YouTube is a video sharing service where users can create their own profile, upload videos, watch, like and comment on other videos.