Chargebee - Chargebee lets you manage subscriptions and payments at scale, handle custom recurring billing scenarios, reduce subscription churn and simplify accounting.

Kahoot! - Kahoot! makes it easy to create, play and share fun learning games in minutes—for any subject, in any language, on any device.

Recurly - Subscription billing and recurring billing management. Recurly offers enterprise-class subscription billing for thousands of companies worldwide.

Sli.do - Slido is the ultimate Q&A and polling platform for live and virtual meetings and events. It offers interactive Q&A, live polls and insights about your audience.

Zuora - Zuora creates cloud-based software on a subscription basis that enables any company in any industry to successfully launch, manage, and transform into a subscription business.

Mentimeter - a web-based polling tool for workshops, conferences & events