Claude Opus 4.5 vs GPT-5.3-Codex-Spark
Anthropic Claude Opus 4.5 | OpenAI GPT-5.3-Codex-Spark | |
|---|---|---|
| Overview | ||
| Company | Anthropic | OpenAI |
| Release date | Nov 24 2025 | Feb 12 2026 |
| Access | Proprietary | Proprietary |
| Specifications | ||
Context window | — | 128k |
| 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. | 90% | — |
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. | 80.9% | — |
Science GPQA DiamondGraduate-level science questions in biology, physics, and chemistry — hard enough that subject-matter PhDs score around 65%. Higher is better. | 87% | — |
| Timeline | ||
| Release gap | Claude Opus 4.5 shipped 80 days before GPT-5.3-Codex-Spark | |
Which is better: Claude Opus 4.5 or GPT-5.3-Codex-Spark?
Claude Opus 4.5 and GPT-5.3-Codex-Spark don't publish scores on any of the same benchmarks, so there's no direct head-to-head comparison. Claude Opus 4.5 shipped 80 days before GPT-5.3-Codex-Spark, 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 Opus 4.5 and GPT-5.3-Codex-Spark don't publish scores on any of the same benchmarks.
Frequently asked questions
Claude Opus 4.5 was released by Anthropic on Nov 24 2025.
GPT-5.3-Codex-Spark was released by OpenAI on Feb 12 2026.
Other comparisons
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