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GPT-5.3 Codex vs Kimi K3
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| Attribute | GPT-5.3 Codex | Kimi K3 |
|---|---|---|
| Scores | ||
| Intelligence (ECI) | 156 | 158 |
| Coding | 56 | 97 |
| Math | — | 80 |
| Reasoning & Knowledge | 84 | 73 |
| Agentic & Tools | 57 | 72 |
| Specifications | ||
| Developer | OpenAI | Moonshot |
| Family | GPT | Kimi |
| Released | Feb 5, 2026 | Jul 16, 2026 |
| Parameters | — | 2.8T |
| Availability | API access | Open weights (non-commercial) |
| Context window | 400K | 1M |
| Price — $/M input | $1.75 | $2.10 |
| Price — $/M output | $14.00 | $10.95 |
| Inputs | text, image, file | text, image, video |
| Outputs | text | text |
| Benchmarks | ||
| APEX | 32% | 51% |
| GPQA Diamond | 92% | 93% |
| Humanity's Last Exam | 43% | 47% |
| METR task horizon | 5.8 h | — |
| SciCode | 53% | 60% |
| SWE-bench Verified | 75% | — |
| Terminal-Bench | 78% | — |
| WebDev Arena | 1370 | 1674 |
| WeirdML | 79% | 83% |
| τ²-bench | 86% | — |
| AIME 2024/2025 | — | 97% |
| ARC-AGI | — | 95% |
| ARC-AGI-2 | — | 60% |
| SimpleBench | — | 61% |
| SimpleQA Verified | — | 51% |
Use-case scores are 0–100 percentile composites across each area’s benchmarks, ranked against every model from the past year. Highlighted cells lead each row. Open a model for the full picture.
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Benchmarks & model data from Epoch AI (CC BY); pricing & specs from OpenRouter. ECI = Epoch Capabilities Index.