Stripe - Online payment processing for internet businesses. Stripe is a suite of payment APIs that powers commerce for online businesses of all sizes. Use Stripe’s payment platform to accept and process payments online for easy-to-use commerce solutions.

Bobby - Keep track of your subscriptions

Recurpay - Recurpay is a subscription SaaS app for businesses that automates recurring billing.

Rocket Money - Find your paid subscriptions and cancel with one click

Stripe Billing Customer Portal - Stripe-hosted page for customers to manage subscriptions

ServiceBot - The new, open source way to run a business online. Subscription billing, Self-service customer portal, service lifecycle management?