Anthropic Claude 2.1 vs OpenAI GPT-5.3-Codex — side-by-side specs.
Anthropic Claude 2.1 | OpenAI GPT-5.3-Codex | |
|---|---|---|
| Overview | ||
| Company | Anthropic | OpenAI |
| Release date | Nov 21 2023 | Feb 5 2026 |
| Model type | — | — |
| Open source | No | No |
| Specifications | ||
Parameters | — | — |
Context window | — | — |
| Benchmarks | ||
| Timeline | ||
| Release gap | Claude 2.1 shipped 807 days before GPT-5.3-Codex | |
Claude 2.1 and GPT-5.3-Codex don't publish scores on any of the same benchmarks, so there's no direct head-to-head comparison. Claude 2.1 shipped 807 days before GPT-5.3-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 2.1 and GPT-5.3-Codex don't publish scores on any of the same benchmarks.