Question 1

Which one should I use for a codebase I already have?

Accepted Answer

Both read and edit files. The difference people report is in how much direction each needs: Claude Code tends to explore before changing, Codex to act sooner. Send a task against your own repository and read both transcripts rather than taking either vendor's benchmark.

Question 2

Do they run the same model?

Accepted Answer

No. Claude Code runs Claude models and Codex runs GPT models, so you are comparing a pairing rather than a harness in isolation. That is the pairing you would actually ship, which is why the page compares it that way.

Question 3

Can I change the options?

Accepted Answer

Yes. Change the available models or add another compatible agent in the composer before sending. All options use normal usage billing unless explicitly marked as sponsored.

Question 4

How does blind comparison work?

Accepted Answer

You know the candidate set, but results are labelled anonymously until you submit your preference. The original sessions remain available after reveal.

Question 5

Is this free?

Accepted Answer

This comparison uses normal compute and model pricing. Specific sponsored activities have their own limited coverage; comparing does not automatically make usage free.

Configuration	Claude Code	Codex
Model	Claude Opus 5.5	GPT-6.1 Sol
Thinking level	High	Medium

Claude Code vs Codex

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