Claude Sonnet 4 vs GPT-5-Codex
Anthropic Claude Sonnet 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. | 30% | 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. | 72.7% | — |
Science GPQA DiamondGraduate-level science questions in biology, physics, and chemistry — hard enough that subject-matter PhDs score around 65%. Higher is better. | 75.4% | — |
| Timeline | ||
| Release gap | Claude Sonnet 4 shipped 116 days before GPT-5-Codex | |
Which is better: Claude Sonnet 4 or GPT-5-Codex?
GPT-5-Codex leads Claude Sonnet 4 on 1 of the 1 benchmark they both report (BullshitBench v2). Claude Sonnet 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 Sonnet 4 at 30%.
Frequently asked questions
Claude Sonnet 4 was released by Anthropic on May 22 2025.
GPT-5-Codex was released by OpenAI on Sep 15 2025.
Other comparisons
Claude Sonnet 4 vs Gemini 3.5 FlashGPT-5-Codex vs Gemini 3.5 FlashClaude Sonnet 4 vs Muse Spark 1.1GPT-5-Codex vs Muse Spark 1.1Claude Sonnet 4 vs Grok 4.5GPT-5-Codex vs Grok 4.5Claude Sonnet 4 vs DeepSeek-V4-ProGPT-5-Codex vs DeepSeek-V4-ProClaude Sonnet 4 vs Mistral Medium 3.5GPT-5-Codex vs Mistral Medium 3.5Claude Sonnet 4 vs Kimi K2.7 CodeGPT-5-Codex vs Kimi K2.7 Code