Claude 3.5 Sonnet (upgraded) vs GPT-5-Codex
Anthropic Claude 3.5 Sonnet (upgraded) | OpenAI GPT-5-Codex | |
|---|---|---|
| Overview | ||
| Company | Anthropic | OpenAI |
| Release date | Oct 22 2024 | 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. | — | 39% |
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. | 49% | — |
| Timeline | ||
| Release gap | Claude 3.5 Sonnet (upgraded) shipped 328 days before GPT-5-Codex | |
Which is better: Claude 3.5 Sonnet (upgraded) or GPT-5-Codex?
Claude 3.5 Sonnet (upgraded) and GPT-5-Codex don't publish scores on any of the same benchmarks, so there's no direct head-to-head comparison. Claude 3.5 Sonnet (upgraded) shipped 328 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.
Direct benchmark comparisons are unavailable — Claude 3.5 Sonnet (upgraded) and GPT-5-Codex don't publish scores on any of the same benchmarks.
Frequently asked questions
Claude 3.5 Sonnet (upgraded) was released by Anthropic on Oct 22 2024.
GPT-5-Codex was released by OpenAI on Sep 15 2025.
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