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 o3OpenAI | GPT-5.5 OpenAI |  Gemini 2.5 Pro | |
|---|---|---|---|
| Vendor | OpenAI | OpenAI | |
| Family | o-series | GPT | Gemini |
| Release date | 2025-04-16 | 2026-04-23 | 2025-03-25 |
| Context window | 200,000 tokens | 400,000 tokens | 2,000,000 tokens |
| Parameters | — | — | — |
| Modality | text, vision | text, vision, audio | text, vision, audio, video |
| License | proprietary | proprietary | proprietary |
| Source | proprietary | proprietary | proprietary |
| Description | Reasoning-focused model in the o-series. | OpenAI's smartest and most intuitive model — successor to GPT-5, with major coding, research, and document workflow gains. GPT-5.5 Pro variant also available for heavier reasoning. | Predecessor to Gemini 3 Pro. |
| Links | |||
| Benchmarks | |||
| MMLU-Pro | — | 87.6% | 84.1% |
| GPQA-D | 87.7% | 89.4% | 84.0% |
| HumanEval | — | 96.8% | — |
| Aider | — | 89.7% | — |
| AIME-25 | 88.9% | 94.2% | — |
| LiveCB | — | 78.9% | — |
| MMMU | — | 78.4% | 72.4% |
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