codex-1 and codex-mini (Codex)

2025-05-16 · Publisher : OpenAI · Domain : Artificial Intelligence

OpenAI launches Codex, a cloud software development agent powered by codex-1, a version of o3 optimized for software engineering, as well as codex-mini, a version of o4-mini for Codex CLI, available in the API.

What changes

  • codex-1 is trained by reinforcement on real development tasks to produce code close to human style, follow instructions and rerun tests until they pass.
  • Each task runs in an isolated cloud sandbox containing the repository, in parallel, for 1 to 30 minutes; AGENTS.md files guide the agent.
  • codex-mini-latest is a smaller version of o4-mini, the default in Codex CLI, designed for low-latency questions and edits.
  • Sign-in to Codex CLI with a ChatGPT account, with free API credits (5 and 50 dollars for Plus and Pro for 30 days).

### Specifications - codex-mini-latest: context 200,000 tokens, output 100,000 tokens, text and image input, text output, knowledge cutoff June 2024; Responses API and Chat Completions. - Codex in ChatGPT: rollout for Pro, Enterprise and Business; Plus from June 3, 2025, with optional internet access. Research preview, with no image input and no correction during a task. ### Pricing Pricing per million tokens (USD) for codex-mini-latest, with a 75% discount on the cache. | | Input | Cached input | Output | | --- | --- | --- | --- | | codex-mini-latest | 1.50 | 0.375 | 6.00 | Codex in ChatGPT: access at no extra cost during the first weeks, then usage limits and purchases. ### Benchmarks Scores published by the vendor: the announcement compares codex-1 with o3 on SWE-bench Verified (tested with 192,000 tokens of context, medium effort, 23 non-runnable tasks excluded) and on an internal benchmark, only in the form of charts. No numerical value is included here. ### Key takeaways Codex opens the era of asynchronous and parallel coding agents, with verification evidence (terminal logs, tests). It remains a research preview whose generated code teams must review before integrating.

Links

Tags : LLM, OpenAI, Codex, Agent, Code, o3