Claude Opus 4 vs GPT-5-Codex
Anthropic Claude Opus 4 | OpenAI GPT-5-Codex | |
|---|---|---|
| Overview | ||
| Company | Anthropic | OpenAI |
| Release date | May 22 2025 | Sep 15 2025 |
| Access | Proprietary | Proprietary |
| Benchmarks | ||
Nonsense detection BullshitBench v2Given a confidently-worded but nonsensical prompt, does the AI spot that it makes no sense and push back — instead of playing along and inventing an answer? The score is how often it clearly called out the nonsense. Higher is better. | 34% | 39%Best |
Coding SWE-Bench VerifiedReal coding tasks pulled from open-source projects — the AI has to find and fix actual bugs. A human-checked version of the original SWE-Bench. Higher is better. | 72.5% | — |
Science GPQA DiamondGraduate-level science questions in biology, physics, and chemistry — hard enough that subject-matter PhDs score around 65%. Higher is better. | 79.6% | — |
| Timeline | ||
| Release gap | Claude Opus 4 shipped 116 days before GPT-5-Codex | |
Which is better: Claude Opus 4 or GPT-5-Codex?
GPT-5-Codex leads Claude Opus 4 on 1 of the 1 benchmark they both report (BullshitBench v2). Claude Opus 4 shipped 116 days before GPT-5-Codex, so benchmark comparisons should account for the intervening progress.
Published specifications for these two models are limited — see each model page for the latest details.
On BullshitBench v2, GPT-5-Codex leads at 39% vs Claude Opus 4 at 34%.
Frequently asked questions
Claude Opus 4 was released by Anthropic on May 22 2025.
GPT-5-Codex was released by OpenAI on Sep 15 2025.
Other comparisons
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