Developer Tools
OpenAI's developer tooling has evolved from a simple API into a rich ecosystem of agentic coding tools, customisable AI configurations, and a public marketplace. Whether you are building software, creating specialised AI assistants, or exploring the GPT Store, this section covers the key products.
In This Section
Codex Agent
OpenAI's agentic software engineering product — autonomous task execution, repo-scale reasoning, and benchmark results.
Codex CLI
The open-source terminal-based coding agent — install, usage, and what it can and cannot do.
Custom GPTs
Build your own GPT configurations with custom instructions, knowledge files, and API Actions — then publish to the GPT Store.
Featured & Built-in GPTs
OpenAI-published and editor-picked GPTs in the Store — how to find and use them without building your own.