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.
PayHere - Run a services business or startup? Charge recurring and one-off payments with beautifully designed payment forms. Get up and running in less than 5 minutes!
Killbill - Open-Source Subscription Billing and Payment Platform
ChargeOver - ChargeOver automates recurring billing, subscription billing, & payment acceptance. A SaaS that integrates with Xero, Quickbooks, & has an API. Free trial.
Chargebee - Chargebee lets you manage subscriptions and payments at scale, handle custom recurring billing scenarios, reduce subscription churn and simplify accounting.
Checkout Page - Sell on your site with customizable checkouts. Tailor-made one page checkouts to sell digital products & services without an ecommerce store.