Define and document API specifications, endpoints, data models, and protocols. Design, build, and implement APIs using programming languages and frameworks. Ensure seamless integration of APIs with internal and external systems. Write unit, integration, and end-to-end tests for APIs, and debug. Create and maintain clear, comprehensive documentation for API consumers. Implement authentication, authorization, encryption, and other security best practices. Monitor and optimize API performance, scalability, and reliability. Manage API versions and ensure backward compatibility. Collaborate with developers, architects, QA engineers, and stakeholders. Provide ongoing support, troubleshoot issues, and implement enhancements.