DeepSeek V3.1 API

deepseek/deepseek-reasoner-v3.1-terminus
DeepSeek V3.1 is a large hybrid reasoning model supporting both thinking and non-thinking modes.
Context
128K tokens
Input
$0.371358 / 1M tokens
Output
$1.3754 / 1M tokens
Released
Aug 28, 2025

How to use DeepSeek V3.1 API

Install any OpenAI-compatible SDK, point it at api.aimlapi.com/v1, and set the model to deepseek/deepseek-reasoner-v3.1-terminus.
import requests

r = requests.post(
    "https://api.aimlapi.com/v1/chat/completions",
    headers={"Authorization": "Bearer " + AIMLAPI_KEY},
    json={
      "model": "deepseek/deepseek-reasoner-v3.1-terminus",
      "messages": [
        {
          "role": "user",
          "content": "Hello!"
        }
      ]
    },
)
print(r.json())
const r = await fetch("https://api.aimlapi.com/v1/chat/completions", {
  method: "POST",
  headers: {
    Authorization: `Bearer ${process.env.AIMLAPI_KEY}`,
    "Content-Type": "application/json",
  },
  body: JSON.stringify({
    "model": "deepseek/deepseek-reasoner-v3.1-terminus",
    "messages": [
      {
        "role": "user",
        "content": "Hello!"
      }
    ]
  }),
});
console.log(await r.json());
curl -X POST https://api.aimlapi.com/v1/chat/completions \
  -H "Authorization: Bearer $AIMLAPI_KEY" \
  -H "Content-Type: application/json" \
  -d '{"model":"deepseek/deepseek-reasoner-v3.1-terminus","messages":[{"role":"user","content":"Hello!"}]}'

OpenAI-compatible — swap the base URL and it works with your existing SDK.

DeepSeek V3.1 API Pricing

TypePrice
Input
$0.371358 / 1M tokens
Output
$1.3754 / 1M tokens
Cached input
$0.371358 / 1M tokens

DeepSeek V3.1 Terminus has a documented pricing caveat: DeepSeek says its API uses cache-hit/cache-miss and peak/off-peak pricing, with off-peak rates half of peak rates, and its V3.1 release note says new pricing

DeepSeek V3.1 Benchmarks

BenchmarkScoreWhat it measuresSourceRetrieved
Intelligence
13.7
Composite score across standardised reasoning, knowledge and problem-solving evaluations, measured independently by Artificial AnalysisSourceSeptember 12, 2026
Math
49.7
Composite score across standardised mathematics evaluations, measured independently by Artificial AnalysisSourceSeptember 12, 2026

DeepSeek V3.1 vs other models

ModelInputOutputContextBest for
DeepSeek V3.1
This page
$0.371358 / 1M tokens
$1.3754 / 1M tokens
128K tokens
Agentic workflows and structured output
$1.625 / 1M
$1.625 / 1M
128K tokens
Reasoning + agents
$0.34385 / 1M tokens
$1.03155 / 1M tokens
128K tokens
Reasoning + agents
$0.039 / 1M
$0.156 / 1M
128K tokens
Reasoning + agents

Frequently asked questions

DeepSeek V3.1 has a 128,000 tokens context window and can return up to 8,000 tokens.

DeepSeek V3.1 takes text as input and returns text.

Use deepseek/deepseek-reasoner-v3.1-terminus as the model id. Requests go to https://api.aimlapi.com/v1/chat/completions.

DeepSeek V3.1 became available on August 28, 2025.

DeepSeek V3.1 is priced at input $0.371358 / 1M tokens, output $1.3754 / 1M tokens, cached input $0.371358 / 1M tokens.

Yes, DeepSeek V3.1 can stream responses as they are generated.

DeepSeek V3.1 was built by DeepSeek.

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