OpenAI originally released a model called Codex in 2021, the technology that powered the original version of GitHub Copilot, before deprecating it in 2023 as newer models superseded it. In 2025, OpenAI reused the Codex name for a substantially different product: a cloud-based autonomous coding agent rather than an autocomplete engine, one that takes a task, works independently in its own sandboxed environment, runs tests, and returns a pull request.
That 2025 relaunch has continued expanding since: a Codex CLI brings the same agentic behavior into a local terminal with human oversight over applied changes, IDE and terminal integrations followed through 2025, and a desktop app arrived in early 2026 alongside continued model upgrades. Anyone researching "Codex" should be aware these are two meaningfully different products sharing one name across different eras.
There's no free tier for the current Codex; access runs through ChatGPT Plus or Pro subscriptions starting around $20 a month, or separate API pricing for developers. For anyone specifically interested in OpenAI's current autonomous coding agent, rather than the historical model that once powered early Copilot, the 2025-and-later Codex is the relevant, actively developed product to evaluate.
