The growing environmental impact of computing has driven the search for more sustainable solutions, leading to the development of the Green Software concept. Green Software refers to the practice of designing, developing, and maintaining software in a way that minimizes energy consumption, reduces carbon footprint, and optimizes resource usage while maintaining high performance and reliability. In this context, the creation of Green Web APIs plays a fundamental role in enabling the construction of efficient systems with low energy consumption. APIs act as intermediaries between different software components, and their design significantly influences the overall resource consumption of applications. Poorly designed APIs can lead to excessive computational overhead, unnecessary data transfers, and high energy usage, negatively impacting both environmental and operational efficiency. This work explores existing patterns and introduces new patterns with best practices for developing sustainable APIs, highlighting design patterns that promote efficiency, such as Green by default and Granular Services, among others that support call optimization, payload reduction, and response aggregation.