OpenAI Open-Sources Codex Harness Framework, Slashing Token Consumption for AI Coding Agents

OpenAI has open-sourced the Codex Harness Framework, the execution engine powering its Codex AI agent, under the Apache-2.0 license as of August 20, 2026. The release includes the core server (app-server), a command-line interface (codex exec), and the official Codex SDK, making the foundational infrastructure of OpenAI's production AI agent publicly available for the first time.