by DeepSeek
DeepSeek-V3.1 Terminus is an update to [DeepSeek V3.1](/deepseek/deepseek-chat-v3.1) that maintains the model's original capabilities while addressing issues reported by users, including language consistency and agent capabilities, further optimizing the model's performance in coding and search agents. It is a large hybrid reasoning model (671B parameters, 37B active) that supports both thinking and non-thinking modes. It extends the DeepSeek-V3 base with a two-phase long-context training process, reaching up to 128K tokens, and uses FP8 microscaling for efficient inference. Users can control the reasoning behaviour with the `reasoning` `enabled` boolean. [Learn more in our docs](https://openrouter.ai/docs/use-cases/reasoning-tokens#enable-reasoning-with-default-config) The model improves tool use, code generation, and reasoning efficiency, achieving performance comparable to DeepSeek-R1 on difficult benchmarks while responding more quickly. It supports structured tool calling, code agents, and search agents, making it suitable for research, coding, and agentic workflows.
| Signal | Strength | Weight | Impact |
|---|---|---|---|
| Recency2026-03-03T20:26:21.905Z | 100 | 15% | +15.0 |
| Capabilities2026-03-03T20:26:21.905Z | 57 | 25% | +14.3 |
| Context Window2026-03-03T20:26:21.905Z | 83 | 15% | +12.4 |
| Versatility2026-03-03T20:26:21.905Z | 33 | 10% | +3.3 |
| Output Capacity2026-03-03T20:26:21.905Z | 20 | 10% | +2.0 |
| Pricing Tier2026-03-03T20:26:21.905Z | 1 | 25% | +0.2 |
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