Magento One Step Checkout - One step checkout is an extension for the ecommerce store.
Fattmerchant - Subscription-based credit card payment processing platform
LandofCoder Magento2 One Step Checkout - The Magento 2 one step checkout with only one- page form helps customers checkout easily as well as saves their time and efforts spent on the last step to complete the purchase.
Helcim - Helcim is a feature-rich online solution that facilitates payment procedures by enabling a range of industries as well as businesses to accommodate several payment options.
MageAnts - Magento 2 Performant Extensions
Gravity Payments - Gravity Payments is a comprehensive credit card processing platform that helps you get paid any way you want, with the least amount of hassle.