Braintree, a division of PayPal, specializes in mobile and web payment systems for ecommerce companies. Braintree provides clients with a merchant account and a payment gateway.
Klaviyo is an email marketing platform for online businesses.
Nginx is a web server that can also be used as a reverse proxy, load balancer, mail proxy and HTTP cache.
PayPal is an online payments system that supports online money transfers and serves as an electronic alternative to traditional paper methods like checks and money orders.
Stripe offers online payment processing for internet businesses as well as fraud prevention, invoicing and subscription management.