DeepSeek Reasoner
Summary
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.
DeepSeek reasoning model for multi-step analysis, math, coding, and tools
Last verified 4 Oct 2026. Every figure on this page links to its source.
Specifications
| Developer | DeepSeek |
|---|---|
| Release date | 1 Dec 2025 [models.dev] |
| Status | Generally available [models.dev] |
| Weights | Open weights [models.dev] |
| Context window | 64K (64,000 tokens) [models.dev] |
| Max output | 66K tokens [models.dev] |
| Knowledge cutoff | Sept 2025 [models.dev] |
| Input | Text [models.dev] |
| Output | Text [models.dev] |
| Reasoning mode | No [models.dev] |
| Tool calling | No [models.dev] |
| Structured output | No [models.dev] |
DeepSeek Reasoner API pricing by provider
USD per million tokens. Sorted by input price.
We do not currently track a paid API listing for this model.
Frequently asked questions
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.
Change history
No changes detected since we started tracking this model. We re-check every source daily.