ResponsesAPI

ResponsesAPI is OpenAI’s next-generation, unified interface for building high-performance, agentic AI applications with native tool use and state management.

This is the new standard: ResponsesAPI streamlines complex AI development, combining the simplicity of Chat Completions with the power of the Assistants API (scheduled for deprecation by 2026). It is built for agentic workflows, featuring native multimodal support (text and images) and a suite of built-in tools (web search, file search, code interpreter). Expect significant performance gains: internal tests show up to an 80% improvement in cache utilization and a 3% boost in model intelligence (e.g., on SWE-bench) when using reasoning models like GPT-5. The API handles conversation state automatically, simplifying multi-turn interactions and allowing you to focus purely on application logic.

https://platform.openai.com/docs/guides/responses