Use OpenAI Developers in Codex to build AI applications, agents, and ChatGPT Apps. Build agents with the Agents API and OpenAI-hosted sandboxes, or use the Agents SDK for application-owned agent loops, handoffs, and guardrails. Connect to the OpenAI Platform (platform.openai.com) to configure API keys, deploy Agents SDK projects locally, scaffold ChatGPT Apps, and prepare submission artifacts.