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

Zelle - Zelle is a fast, safe and easy way to send money in minutes to your friends and family.

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.

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

PaymentSpring - The all-in-one, developer-driven payment gateway

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