Compare models
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 DeepSeek-R1DeepSeek | DeepSeek-V4-Pro DeepSeek |  GPT-5.5OpenAI | |
|---|---|---|---|
| Vendor | DeepSeek | DeepSeek | OpenAI |
| Family | DeepSeek | DeepSeek | GPT |
| Release date | 2025-01-20 | 2026-04-22 | 2026-04-23 |
| Context window | 128,000 tokens | 1,000,000 tokens | 400,000 tokens |
| Parameters | 671B | 1.6T (49B active) | — |
| Modality | text | text | text, vision, audio |
| License | MIT | MIT | proprietary |
| Source | open weights | open weights | proprietary |
| Description | Reasoning-focused open-weight model. | DeepSeek's flagship open-weight MoE. 1.6T parameters with 49B activated, 1M-token context, and a hybrid attention scheme (CSA + HCA) that delivers long-context inference at ~27% of V3.2's FLOPs. | 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. |
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