Adyen

Adyen's API is comprehensive and enterprise-grade, supporting hundreds of global payment methods through a unified platform. The RESTful API uses both API key and basic authentication, with extensive documentation and multiple SDKs available. It covers online payments, point-of-sale, platforms, payouts, and disputes extensively with strong versioning support.

The API includes advanced features like 3D Secure 2, tokenization, and fraud management. However, it's complex for beginners and requires understanding of payment processing concepts. Rate limiting and pricing are transaction-based with Interchange++ model. Ideal for businesses needing global payment processing with extensive customization options and omnichannel support.