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The short answer
Claude Code is the more mature agent and stronger on large multi-file work. Codex is improving quickly and is included with a ChatGPT subscription.
The deciding factor for most people is which subscription they already have. Both are bundled, so the cheaper option is usually "the one you are already paying for."
| Claude Code | Codex | |
|---|---|---|
| Made by | Anthropic | OpenAI |
| Included with | Claude Pro / Max | ChatGPT paid plans |
| Maturity | Longer in market | Newer, improving fast |
| Multi-file reasoning | Excellent | Good |
| Runs in terminal | Yes | Yes |
| Reads & edits your files | Yes | Yes |
What they have in common
Both are agents that run in your terminal, read your actual codebase, make changes across files, run tests and report back. Both are included with their parent subscription rather than sold separately.
Both represent the same important shift: away from copy-pasting between a browser and an editor, and towards describing an outcome and reviewing a diff.
Where Claude Code is ahead
Multi-file reasoning. On tasks where the work spans a dozen files and the difficulty is in how they interact, Claude Code is more consistent. It catches more of the places a change needs to land.
Maturity. It has been in developers' hands longer, which shows in the rough edges that are not there — recovery when something fails, sensible defaults, and a larger body of community knowledge when you get stuck.
Where Codex competes
It is included with ChatGPT. If you already pay for ChatGPT, Codex costs nothing extra — and "free with what I already have" beats "slightly better for another $20/month" for a lot of people.
It is improving quickly. The gap has narrowed noticeably. Anyone stating a permanent verdict here is overreaching; check both if you can.
How to decide
Already pay for ChatGPT? Use Codex first. It is included, and it may be entirely sufficient.
Already pay for Claude? Use Claude Code. Same logic.
Paying for neither? Claude, if agentic coding is the main reason you are subscribing. The multi-file advantage matters most on exactly the work you would buy an agent for.
One budgeting note: agentic sessions consume usage allowance quickly on either platform. Factor that in rather than assuming the base tier covers unlimited agent work.
Common questions
Is Codex free?
Which is better for large codebases?
Can I use both?
Both come bundled — use what you have
Claude Code is included with Claude Pro. If you're starting fresh and agentic coding is the main use case, that's the stronger option.