The short answer
Claude Code and Codex are both strong, general-purpose coding agents, and either one can carry a real project. The difference is in how they like to work:
- Choose Claude Code when you want an agent that works closely with you in a long session: exploring an unfamiliar codebase, talking through a design, and making coordinated changes across many files, with rich ways to customise it (project memory, subagents, hooks, skills and slash commands).
- Choose Codex when you want to hand off well-scoped tasks and pick up the result: it runs locally in your terminal or IDE, or in a cloud sandbox connected to your GitHub repo, so you can start several tasks and review each one when it's done.
- Use both when you have more work than one agent can do. Each tool has its own strengths and its own usage limits, and many developers already pay for both. Running them side by side gives you more throughput and a second opinion on every change.
Claude Code vs Codex at a glance
| Claude Code | Codex | |
|---|---|---|
| Made by | Anthropic | OpenAI |
| Models | Claude models | OpenAI models |
| Where it runs | Terminal, IDE extensions (VS Code, JetBrains), desktop app, web and mobile | Terminal (open-source CLI), IDE extension, ChatGPT and Codex apps, cloud sandboxes |
| Working style | Interactive sessions you steer as it goes | Delegated tasks you review when they finish, locally or in the cloud |
| Project instructions | CLAUDE.md | AGENTS.md |
| Customisation | Subagents, hooks, skills, slash commands, plugins, MCP servers | Profiles, sandbox and approval modes, MCP servers, AGENTS.md per directory |
| Parallel work | Several sessions, often in separate git worktrees | Several local sessions or cloud tasks at once |
| Code review | Review in a session or through its GitHub integration | Built-in review of local changes and GitHub pull requests |
| Pricing | Included in Claude Pro and Max plans, or pay per token through the API | Included in ChatGPT plans, or pay per token through the API |
| Best at | Deep, multi-file work where you want to stay in the loop | Well-defined tasks you want to run in the background |
Both products change fast. Check Anthropic's and OpenAI's own docs for current plans, models and limits.
When to use Claude Code
Claude Code is at its best when the task needs judgment along the way.
- Getting to know a codebase. Ask it to trace how a request flows through your app, explain why a module exists, or map out where a change will land before anything is edited.
- Large, coordinated changes. Refactors that touch twenty files, migrations that need the schema, API and UI to move together, or a rename that has to stay consistent everywhere.
- Pairing on design. Talk through options, ask it to sketch two approaches, then pick one. Plan mode lets it propose a plan for you to approve before it writes code.
- A workflow you want to shape.
CLAUDE.mdgives it lasting project context, subagents split research from implementation, hooks run your formatter or tests automatically, and skills package repeatable procedures your whole team can share.
For a deeper look at what Claude Code does on its own and what changes when you run it across several projects, see Chief + Claude Code.
When to use Codex
Codex is at its best when the task is clear and you'd rather not watch it happen.
- Well-scoped implementation. "Add an endpoint that returns the last 30 invoices, with tests" is the kind of task Codex picks up and finishes cleanly.
- Background and cloud work. Start a task in a cloud sandbox from the web or your phone, close your laptop, and review the diff or pull request later.
- Many small tasks at once. Bug fixes, test coverage, dependency bumps and documentation updates can run side by side.
- Reviewing code. Codex can review your local changes or a GitHub pull request and point out issues before you merge.
- An open-source CLI. The Codex CLI is open source, so you can read exactly how it runs commands and handles approvals.
For more on how Codex fits into a larger workflow, see Chief + Codex.
Why many developers use both
The Codex vs Claude Code question often ends with "both", for practical reasons:
- Different strengths. Some tasks suit an interactive session and some suit a background run. Having both means every task goes to a tool that fits it.
- More capacity. Each subscription has its own usage limits. When one is busy or resetting, the other keeps your work moving.
- A second opinion. Asking one agent to review the other's work catches issues that a model reviewing its own output can miss. The multi-provider orchestration guide covers this pattern in detail.
- Comparing on your own code. Benchmarks are a starting point. Running both on your real tasks is the fastest way to learn which one you prefer for which kind of work.
The hard part is coordination: two agents in two terminals, each with its own context, editing the same repo. That's the problem Chief solves.
How Chief lets you use Claude Code and Codex together
Chief is an AI agent manager. It plans your project as milestones, runs each one with the coding agent you choose, and checks the result before it reaches you. Claude Code and Codex are both built in.
- Pick the agent per project or per milestone. Use Claude Code for the refactor and Codex for the endpoint and tests, in the same plan.
- Runs on your computer, with your subscriptions. The Chief relay starts Claude Code and Codex on your own machine, signed in to your own accounts. Your code stays where it is.
- Work runs in the right order. Chief sequences milestones by their dependencies, so the schema change lands before the endpoint that needs it, whichever agent builds each one.
- One review step for both. Chief checks each milestone against its acceptance criteria, whichever agent built it, and collects the decisions that need you in one place.
- Ask Chief from either tool. Chief's MCP server connects to both Claude Code and Codex, so you can ask what's waiting on you or propose the next milestone from the session you already have open.
You don't have to settle the Claude Code vs Codex question up front. Start with the one you already use, add the other when you want more capacity, and let Chief keep both pointed at the right work.
Run Claude Code and Codex together in Chief →
FAQ
Is Codex better than Claude Code?
Neither is better at everything. Claude Code is a great fit for interactive, multi-file work where you want to steer as it goes. Codex is a great fit for well-scoped tasks you want to hand off, locally or in the cloud. Many developers use both and pick per task.
Can I use Claude Code and Codex on the same project?
Yes. Give each agent its own branch or git worktree, or its own part of the codebase, so they don't edit the same files at the same time, and keep shared instructions in both CLAUDE.md and AGENTS.md. Chief helps by splitting the work into milestones, running them in dependency order and letting you choose the agent for each one.
Which is cheaper, Claude Code or Codex?
Both are included in their makers' paid subscriptions and can also be billed per token through an API key. Your real cost depends on the plan and how much you use it. See AI coding agent costs for a breakdown.
Do Claude Code and Codex use the same instruction files?
Not by default. Claude Code reads CLAUDE.md and Codex reads AGENTS.md. Both are plain Markdown, so many teams keep one file and point the other at it.
How does Chief work with Claude Code and Codex?
Chief plans your project as milestones and dispatches each one to Claude Code or Codex through a relay on your own computer, using your existing subscriptions. It reviews each result against its acceptance criteria before asking for your approval.