OpenAI Codex CLI
OpenAI Codex CLI is an open-source command-line tool for AI-assisted coding, built by OpenAI (released 2025-05). OpenAI Codex CLI integrates with 7 verified models, including GPT-5.4 Mini, GPT-5.4, and GPT-5.3-Codex. It's free and open source. Use this page to compare model coverage, pricing, release timing, source availability, and adjacent harnesses before choosing an AI coding workflow.
Overview
Open-source command-line coding agent released April 2025 that runs code, browses files, and executes multi-step tasks in a sandboxed environment using OpenAI models.
Best LLMs for this agent
Default — latest frontier agentic coding model
Pricing and Provider Comparison
Hosted agents expose plan pricing. Bring-your-own-key agents pass the main cost through the model provider route you configure.
Agent access tiers
| Tier | Price | Includes |
|---|---|---|
| Free | Free | Limited Codex access |
| ChatGPT Go | $8/mo | Basic Codex access, entry-level paid tier |
| ChatGPT Plus | $20/mo | Codex included, message limits per 5hrs |
| ChatGPT Pro | $200/mo | Highest priority, maximum message limits |
| ChatGPT Business | $30/mo | Workspace credits, admin controls |
| Enterprise | Custom | Unlimited high-speed access, SSO, advanced security |
Provider routes for recommended models
| Model | Provider | Input / 1M | Output / 1M | Notes |
|---|---|---|---|---|
| GPT-5.4 | OpenAI API | $2.50 | $15.00 | Batch pricing listed; Cache reads listed |
| GPT-5.4 | OpenRouter | $2.5 | $15 | Published token price |
| GPT-5.4 | Vercel AI Gateway | $2.5 | $15 | Cache reads listed |
Featured Model Specs
| Model | Lab | Released | Context | Reasoning | Open source |
|---|---|---|---|---|---|
| GPT-5.4 | OpenAI | 2026-03-05 | 1.05m | Yes | No |
| GPT-5.4 Mini | OpenAI | 2026-03-05 | 400k | Yes | No |
| GPT-5.3-Codex | OpenAI | 2026-02-05 | 400k | Yes | No |
| GPT-5.2 Codex | OpenAI | 2025-12-18 | — | Yes | No |
| GPT-5.2 | OpenAI | 2025-12-11 | 400k | Yes | No |
Model Compatibility Matrix
| Model | Lab | Default | Access tier | Notes |
|---|---|---|---|---|
| GPT-5.4 | OpenAI | Yes | ChatGPT Plus | Default — latest frontier agentic coding model |
| GPT-5.4 Mini | OpenAI | No | ChatGPT Plus | Smaller frontier agentic coding model |
| GPT-5.3-Codex | OpenAI | No | ChatGPT Plus | Frontier Codex-optimized agentic coding model |
| GPT-5.2 Codex | OpenAI | No | ChatGPT Plus | Frontier agentic coding model based on GPT-5.2 |
| GPT-5.2 | OpenAI | No | ChatGPT Plus | Optimized for professional work and long-running agents |
| GPT-5.1 Codex Max | OpenAI | No | ChatGPT Plus | Codex-optimized flagship for deep and fast reasoning |
| GPT-5.1 Codex Mini | OpenAI | No | ChatGPT Plus | Cheaper, faster, but less capable — optimized for Codex |
Underlying Models
Compare to Similar Harnesses
FAQ
What is OpenAI Codex CLI?
OpenAI Codex CLI is an open-source command-line tool for AI-assisted coding, built by OpenAI (released 2025-05). Engineers run it from a terminal, where it can inspect repositories, edit files, call tools, and drive repeatable agentic coding workflows across local projects. It is primarily used for agentic coding from a local shell.
What models does OpenAI Codex CLI support?
OpenAI Codex CLI runs GPT-5.4 Mini, GPT-5.4, GPT-5.3-Codex, GPT-5.2 Codex, GPT-5.2, and 2 more.
How much does OpenAI Codex CLI cost?
OpenAI Codex CLI is free and open source. You pay only for the underlying model API usage.
Is OpenAI Codex CLI open source?
Yes, OpenAI Codex CLI is open-source software.
What are alternatives to OpenAI Codex CLI?
Alternatives include Mistral Vibe, Claude Code, and Aider.
When was OpenAI Codex CLI released?
OpenAI Codex CLI was released in 2025-05.