DeepSeek V3.1 Terminus
VerifiedOpen-weight LLM built for 160K-token text tasks.
About DeepSeek V3.1 Terminus
DeepSeek V3.1 Terminus uses a transformer-based design scaled for very long sequences. Its open-weight release enables direct inspection, fine-tuning, and local deployment by researchers and engineers. This approach removes licensing barriers common in closed models.
The primary strength lies in maintaining coherence across documents, codebases, or multi-turn dialogues that exceed typical context limits. It suits workloads requiring synthesis of large text collections without truncation. Users commonly apply it to technical writing, code review, and detailed question answering.
Capabilities
How DeepSeek V3.1 Terminus compares
DeepSeek V3.1 Terminus (striped bar) vs other language models on intelligence, speed and price.
Price
USD per 1M output tokens · Lower is better · DeepSeek V3.1 Terminus ranks #38 of 66
Sources: Artificial Analysis (intelligence, speed) · OpenRouter (price).
Best for
Long Document Analysis
The 163840-token context allows the model to process and reason over entire books, legal contracts, or research papers without chunking.
Large-Scale Codebase Tasks
It handles full repositories or multi-file projects in one session, supporting refactoring, debugging, and architecture reviews.
Extended Multi-Turn Reasoning
Sustains coherent reasoning across very long conversations or step-by-step problem-solving workflows.
Strengths & limitations
Strengths
- +Very large context window support
- +Strong coding and technical reasoning
- +Efficient handling of extended inputs
Limitations
- –Text-only modality
- –No native vision or multimodal support
- –May require careful prompting for complex tasks
Cost calculator
Estimate what DeepSeek V3.1 Terminus would cost for your usage.
Based on DeepSeek V3.1 Terminus's $0.27/1M input · $0.95/1M output. Estimate only — actual cost varies by provider and caching.
Quick start
OpenRouter's API is OpenAI-compatible — most SDKs work by just swapping the base URL. Only the model slug changes between models.
import OpenAI from "openai";
const client = new OpenAI({
baseURL: "https://openrouter.ai/api/v1",
apiKey: process.env.OPENROUTER_API_KEY,
});
const completion = await client.chat.completions.create({
model: "deepseek/deepseek-v3.1-terminus",
messages: [{ role: "user", content: "Hello!" }],
});
console.log(completion.choices[0].message.content);Model slug: deepseek/deepseek-v3.1-terminus
Editor's verdict
DeepSeek V3.1 Terminus is DeepSeek's open-weight language models with a 164K-token context window.
At $0.95 per 1M output tokens, it is very cost-efficient for its class.
As an open-weight model you can self-host it or call it through a hosted API.
Best suited to very large context window support and strong coding and technical reasoning.
Frequently asked questions
The model provides a context window of 163840 tokens.
User reviews
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