Developed an OAuth2 API client for LLM services in the knownsec/aipyapp repository, focusing on secure token retrieval and efficient authorization header management. The implementation leveraged Python and the httpx library to improve performance and concurrency, while a follow-up refactor enabled token reuse and addressed an incompatible client issue, reducing authentication overhead. The work emphasized clear separation of concerns and maintainable code structure, resulting in faster, more secure API calls and simplified maintenance. By applying expertise in API development, client-server architecture, and OAuth2 protocols, the developer delivered a robust solution that enhanced both security and operational efficiency for API integrations.