Chargebee - Chargebee lets you manage subscriptions and payments at scale, handle custom recurring billing scenarios, reduce subscription churn and simplify accounting.
Giftbit Payment API - Stripe for gift cards
Recurly - Subscription billing and recurring billing management. Recurly offers enterprise-class subscription billing for thousands of companies worldwide.
Raise - The easiest way to save money on the go
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.
Gemnote - Handwritten cards & premium custom gifts for companies