Stripe

https://stripe.com/

Stripe helps power millions of small businesses in more than 100 countries and across nearly every industry. Start collecting payments via card, ACH, or other popular payment methods instantly. Stripe provides billing software for everything from per-seat pricing to metered billing out of the box. It also gives you the ability to set custom pricing, automate the collection process, and sync billing and payment data with your other accounting software and tools.

Stripe