Review of OpenAI Codex
OpenAI Codex is an AI coding agent built by OpenAI, designed to execute engineering tasks end-to-end: feature development, complex refactors, migrations, debugging, documentation and tests. Available via CLI, IDE extensions and cloud, Codex orchestrates several agents in parallel to deliver in days what would take a human team weeks. Included in ChatGPT Plus, Pro and Business, the agent is powered by GPT-5.3-Codex-Spark and extends its capabilities via skills and automations.
OpenAI Codex: Agent CLI et cloud qui exécute du code, ouvre des PR et travaille en parallèle sur vos projets.
Best for
- Solo developers accelerating features
- Engineering teams delegating repetitive tasks
- Startups shipping fast MVPs
- DevOps automating triage and monitoring
Not ideal for
- Non-tech profiles without code understanding
- Highly security-sensitive projects without audit
- Teams without code review process
- Use cases without clear Git repository
Pros & cons
- ✅ Autonomous agent for features and refactors
- ✅ Parallel execution via worktrees and cloud
- ✅ Skills to customize capabilities
- ✅ Automations for CI/CD, triage, monitoring
- ✅ Included in ChatGPT Plus at $20/month
- ⚠️ Costs that explode on intensive use
- ⚠️ Quotas on 5h rolling windows on Plus
- ⚠️ Shell skills require PR validation
- ⚠️ Pricing token-based since April 2026
Our verdict
OpenAI Codex has become in 2026 one of the references for AI coding agents, and one of the most accomplished incarnations of the concept of AI able to deliver complete engineering tasks. Its native integration in ChatGPT Plus at $20/month is a massive pricing argument against competitors like Cursor, Claude Code or GitHub Copilot Workspace, and parallel orchestration via worktrees and cloud allows parallelizing the development of several features simultaneously. Skills and automations open a very large customization field, transforming Codex into a real production copilot able to orchestrate ticket triage, alert monitoring and deployments. Limits concern cost control (token-based pricing since April 2026 can rapidly increase the bill) and the systematic need for human validation on generated PRs. For modern engineering teams that want to integrate an AI agent into their workflow, Codex is today essential in the shortlist.
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FAQ
Is OpenAI Codex free?
No, Codex is included in ChatGPT subscriptions Plus ($20/month), Pro ($200/month) and Business/Enterprise. There is no fully free plan.
What is the difference between Codex and ChatGPT?
ChatGPT is a generalist conversational assistant while Codex is a code-specialized agent able to execute, test and ship features end-to-end in a Git repository.
Can Codex work on multiple projects in parallel?
Yes, Codex uses Git worktrees and a cloud execution environment to orchestrate multiple agents simultaneously, particularly useful to handle tickets in parallel.
What is a Codex Skill?
A Skill is a customized capability that extends Codex beyond code: codebase understanding, prototyping, documentation, third-party tool integrations. Skills are configurable per team.
Is Codex secure for proprietary code?
Yes, OpenAI offers enterprise guarantees (data residency, no-train on customer data, SSO, audit logs) on Business and Enterprise plans for proprietary code.