# DeepSeek Reasoner

> DeepSeek Reasoner is an open-weight language model from DeepSeek, released on 1 Dec 2025. It accepts text and generates text, with a 64K-token context window and up to 66K output tokens per response.

Source page: https://www.aimodel.directory/models/deepseek-reasoner
Last verified: 4 Oct 2026

## Specifications

- **Developer:** DeepSeek
- **Release date:** 1 Dec 2025 (source: models.dev, https://github.com/sst/models.dev/blob/dev/providers/nano-gpt/models/deepseek-reasoner.toml)
- **Status:** Generally available (source: models.dev, https://github.com/sst/models.dev/blob/dev/providers/nano-gpt/models/deepseek-reasoner.toml)
- **Weights:** Open weights (source: models.dev, https://github.com/sst/models.dev/blob/dev/providers/nano-gpt/models/deepseek-reasoner.toml)
- **Context window:** 64K (64,000 tokens) (source: models.dev, https://github.com/sst/models.dev/blob/dev/providers/nano-gpt/models/deepseek-reasoner.toml)
- **Max output:** 66K tokens (source: models.dev, https://github.com/sst/models.dev/blob/dev/providers/nano-gpt/models/deepseek-reasoner.toml)
- **Knowledge cutoff:** Sept 2025 (source: models.dev, https://github.com/sst/models.dev/blob/dev/providers/nano-gpt/models/deepseek-reasoner.toml)
- **Input:** Text (source: models.dev, https://github.com/sst/models.dev/blob/dev/providers/nano-gpt/models/deepseek-reasoner.toml)
- **Output:** Text (source: models.dev, https://github.com/sst/models.dev/blob/dev/providers/nano-gpt/models/deepseek-reasoner.toml)
- **Reasoning mode:** No (source: models.dev, https://github.com/sst/models.dev/blob/dev/providers/nano-gpt/models/deepseek-reasoner.toml)
- **Tool calling:** No (source: models.dev, https://github.com/sst/models.dev/blob/dev/providers/nano-gpt/models/deepseek-reasoner.toml)
- **Structured output:** No (source: models.dev, https://github.com/sst/models.dev/blob/dev/providers/nano-gpt/models/deepseek-reasoner.toml)

## API pricing (USD per 1M tokens)

| Provider | Input | Output | Cached input | Context |
|---|---|---|---|---|

## FAQ

### What is the context window of DeepSeek Reasoner?

DeepSeek Reasoner has a context window of 64,000 tokens (64K) and can generate up to 65,536 tokens in a single response, according to models.dev.

### Is DeepSeek Reasoner open source?

DeepSeek Reasoner is an open-weight model. Check the license terms before commercial use.

### When was DeepSeek Reasoner released?

DeepSeek released DeepSeek Reasoner on 1 Dec 2025, according to models.dev.

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Data licensed CC BY 4.0. Cite as: AI Model Directory, "DeepSeek Reasoner", https://www.aimodel.directory/models/deepseek-reasoner