Key Differences Between the OpenAI Responses API and the Assistants API

OpenAI has introduced the Responses API as a simpler, more efficient replacement for the existing Assistants API, which is planned for deprecation. The new API streamlines building AI agents by managing conversation state server-side, using a `previous_response_id` to maintain context without resending the entire chat history. Key advantages of the Responses API include reduced complexity, built-in tools for web and file search, and faster performance. Developers can maintain conversational context by passing the ID of the last response in subsequent requests, though all previous tokens are still billed.