Intercom - Intercom is a customer relationship management and messaging tool for web businesses. Build relationships with users to create loyal customers.
PayPal - PayPal is the faster, safer way to pay online without sharing financial details, send and receive money or accept credit and debit cards as a seller
Drift - A messaging app that helps you grow your business.
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.
C++ - Has imperative, object-oriented and generic programming features, while also providing the facilities for low level memory manipulation
Braintree - An all-in-one solution to accept, process, and split payments in your mobile app or online - from small business to large enterprise.