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

Google Authenticator - Google Authenticator is a multifactor app for mobile devices.

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

Microsoft Authenticator - One app to quickly and securely verify your identity online, for all of your accounts.

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.

Authenticator - Authenticator is a simple, free, and open source two-factor authentication app.