Google: Gemini 3.1 Pro Preview · fastrouter

Google's gemini-3.1-pro-preview (also called Gemini 3.1 Pro Preview) is a preview-stage, multimodal AI model from Google DeepMind, optimized for advanced reasoning, agentic workflows, software engineering, and complex problem-solving across text, images, video, audio, and PDFs. It refines the Gemini 3 Pro series with improved thinking, token efficiency, factual consistency, and reliability for multi-step tasks, tool use, and long-horizon stability. Key specs include a 1M input token context window (1,048,576 tokens), 64K-65K output tokens, and support for capabilities like function calling, structured outputs, code execution, search grounding, and a new "MEDIUM" thinking level for balancing cost, speed, and performance.

Base model All models on this base All models of the provider to the provider

Input, $/1M $2.00

Output, $/1M $12.00

Cache read $0.20

Cache write —

Context 1 048 576

Max output 65 536

Accepts audio, files, images, text, video

Last checked 04.11.2026 12:00:14 UTC

Source provider's page

Price alerts

API

OpenAI-compatible API: the official OpenAI SDKs work with this base URL. Replace YOUR_API_KEY with your key from the provider.

API base URL	`https://go.fastrouter.ai/api/v1`
Endpoint	`https://go.fastrouter.ai/api/v1/chat/completions`
Model id	`google/gemini-3.1-pro-preview`

curl

curl https://go.fastrouter.ai/api/v1/chat/completions \
  -H "Authorization: Bearer YOUR_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{"model": "google/gemini-3.1-pro-preview", "messages": [{"role": "user", "content": "Hello!"}], "max_tokens": 256}'

Python

import requests

r = requests.post(
    "https://go.fastrouter.ai/api/v1/chat/completions",
    headers={"Authorization": "Bearer YOUR_API_KEY"},
    json={
      "model": "google/gemini-3.1-pro-preview",
      "messages": [
        {
          "role": "user",
          "content": "Hello!"
        }
      ],
      "max_tokens": 256
    },
)
print(r.json())

JavaScript

const r = await fetch("https://go.fastrouter.ai/api/v1/chat/completions", {
  method: "POST",
  headers: {Authorization: "Bearer YOUR_API_KEY", "Content-Type": "application/json"},
  body: JSON.stringify({
    "model": "google/gemini-3.1-pro-preview",
    "messages": [
      {
        "role": "user",
        "content": "Hello!"
      }
    ],
    "max_tokens": 256
  }),
});
console.log(await r.json());

Request (JSON)

{
  "model": "google/gemini-3.1-pro-preview",
  "messages": [
    {
      "role": "user",
      "content": "Hello!"
    }
  ],
  "max_tokens": 256
}

Response (JSON)

{
  "id": "chatcmpl-...",
  "object": "chat.completion",
  "model": "google/gemini-3.1-pro-preview",
  "choices": [
    {
      "index": 0,
      "message": {
        "role": "assistant",
        "content": "Hi! How can I help?"
      },
      "finish_reason": "stop"
    }
  ],
  "usage": {
    "prompt_tokens": 9,
    "completion_tokens": 12,
    "total_tokens": 21
  }
}

The address is taken from the provider's model list; check it against the provider's documentation.

Provider's API documentation

Source: AI Rate Card, https://airatecard.com/en/c/offer%3Afastrouter%7Cgoogle/gemini-3.1-pro-preview, prices checked 2026-11-04; seller's page: https://fastrouter.ai/models/google/gemini-3.1-pro-preview

Technical details

ID: offer:fastrouter|google/gemini-3.1-pro-preview