DeepSeek DeepSeek V2.5 vs OpenAI GPT-5.3-Codex — side-by-side specs.
DeepSeek DeepSeek V2.5 | OpenAI GPT-5.3-Codex | |
|---|---|---|
| Overview | ||
| Company | DeepSeek | OpenAI |
| Release date | Sep 2024 | Feb 5 2026 |
| Model type | — | — |
| Open source | Yes | No |
| Specifications | ||
Parameters | — | — |
Context window | — | — |
| Benchmarks | ||
Science reasoning GPQA Diamond | — | — |
Software engineering SWE-Bench Verified | — | — |
Multimodal understanding MMMU | — | — |
| Timeline | ||
| Release gap | DeepSeek V2.5 shipped 522 days before GPT-5.3-Codex | |
DeepSeek V2.5 and GPT-5.3-Codex do not have directly comparable benchmark scores published on GPQA Diamond, SWE-Bench Verified, or MMMU. DeepSeek V2.5 shipped 522 days before GPT-5.3-Codex, so benchmark comparisons should account for the intervening progress.
DeepSeek V2.5 is an open-source / open-weight model; GPT-5.3-Codex is proprietary.
Direct benchmark comparisons are unavailable — at least one of these models has not published scores on GPQA Diamond, SWE-Bench Verified, or MMMU.