APIs, or Application Programming Interfaces, are crucial for enabling communication between different software applications, serving as logical contracts between client requests and server responses. Emerging over the last two decades, various API architecture styles such as REST, gRPC, GraphQL, and OpenAPI have been developed to improve this communication. REST is a resource-based architecture known for its flexibility and scalability, despite limitations like over-fetching and under-fetching data. gRPC, an open-source RPC framework, offers high performance and efficient binary data transmission, though it lacks browser support. GraphQL addresses REST's data fetching issues by allowing precise data queries, enhancing scalability but requiring a steep learning curve. OpenAPI provides a standardized format for REST APIs, facilitating machine-readable API definitions, though it doesn't cover all service styles. Deploying APIs on serverless platforms like Koyeb can optimize cloud resource efficiency, offering features like autoscaling and global edge networks.