Mistral Mistral Medium 3.5 | OpenAI GPT-5.3-Codex | |
|---|---|---|
| Overview | ||
| Company | Mistral | OpenAI |
| Release date | Apr 29 2026 | Feb 5 2026 |
| Model type | — | — |
| Open source | Yes | No |
| Specifications | ||
Parameters | 128B | — |
Context window | 256k | — |
| Benchmarks | ||
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. | 77.6% | — |
| Timeline | ||
| Release gap | GPT-5.3-Codex shipped 83 days before Mistral Medium 3.5 | |
Mistral Medium 3.5 and GPT-5.3-Codex don't publish scores on any of the same benchmarks, so there's no direct head-to-head comparison. GPT-5.3-Codex shipped 83 days before Mistral Medium 3.5, so benchmark comparisons should account for the intervening progress.
Mistral Medium 3.5 is an open-source / open-weight model; GPT-5.3-Codex is proprietary.
Direct benchmark comparisons are unavailable — Mistral Medium 3.5 and GPT-5.3-Codex don't publish scores on any of the same benchmarks.