Gemini 3.1 Pro Preview API: pricing, integration and limits

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Published: Oct 24, 2026, 6:11 AM UTC · Updated: Oct 24, 2026, 5:18 PM UTC

Exact ID: gemini-3.1-pro-preview. Models available to your key: GET /v1/models.

Gemini 3.1 Pro Preview API pricing

Cost calculator for Gemini 3.1 Pro Preview

Context and capabilities of Gemini 3.1 Pro Preview

The manufacturer specifies an input limit of 1,048,576 and a maximum output of 65,536 tokens for its own API (specification: Google, checked Oct 24, 2026, 6:11 AM UTC). These are manufacturer limits, not verified effective API429 limits: test very long contexts on your own request.

API429 capabilities published for this exact ID: chat reasoning search vision . Test any mode missing from this list on your own request.

Speed and errors of Gemini 3.1 Pro Preview over 24 hours

Over the last 24 hours: mean successful response time — 21 s; service error rate — 0%. Data as of Oct 25, 2026, 8:06 AM UTC.

Source: public 24-hour statistics. The mean is neither a median nor a response time guarantee.

How to connect Gemini 3.1 Pro Preview: curl, Python, JavaScript

Create a key, check your balance and set API429_API_KEY on the server. The request is paid from your balance; Python and JavaScript first check that the model is available to your key.

curl

Before generation, check the exact ID in the response from GET https://gateway.api429.com/v1/models using the same Bearer key.

curl --fail-with-body https://gateway.api429.com/v1/chat/completions \
  -H "Authorization: Bearer $API429_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{"model":"gemini-3.1-pro-preview","messages":[{"role":"user","content":"Follow this instruction: Return three items; if data is absent, write unknown. Data: no cost is stated; the deadline is 8 days. Return deadline, cost and the main question for the author."}],"max_tokens":512,"stream":false}'

Python 3

import json
import os
import urllib.request

key = os.environ["API429_API_KEY"]
base = "https://gateway.api429.com/v1"
headers = {"Authorization": "Bearer " + key, "Content-Type": "application/json"}
models_request = urllib.request.Request(base + "/models", headers=headers)
with urllib.request.urlopen(models_request, timeout=30) as response:
    available = {item["id"] for item in json.load(response)["data"]}
model = "gemini-3.1-pro-preview"
if model not in available:
    raise ValueError("Model is unavailable to this key")
payload = json.loads("{\"model\":\"gemini-3.1-pro-preview\",\"messages\":[{\"role\":\"user\",\"content\":\"Follow this instruction: Return three items; if data is absent, write unknown. Data: no cost is stated; the deadline is 8 days. Return deadline, cost and the main question for the author.\"}],\"max_tokens\":512,\"stream\":false}")
request = urllib.request.Request(base + "/chat/completions",
    data=json.dumps(payload).encode("utf-8"), headers=headers, method="POST")
with urllib.request.urlopen(request, timeout=60) as response:
    result = json.load(response)
choice = result["choices"][0]
if choice.get("finish_reason") != "stop" or not choice.get("message", {}).get("content"):
    raise ValueError("Incomplete or empty response")
print(choice["message"]["content"])
print(result.get("usage"))

JavaScript: Node.js 18+

const key = process.env.API429_API_KEY;
if (!key) throw new Error("Set API429_API_KEY");
const base = "https://gateway.api429.com/v1";
const headers = { Authorization: "Bearer " + key, "Content-Type": "application/json" };
const model = "gemini-3.1-pro-preview";
const available = await fetch(base + "/models", { headers, signal: AbortSignal.timeout(30000) });
if (!available.ok) throw new Error("Models HTTP " + available.status);
if (!(await available.json()).data.some(item => item.id === model)) throw new Error("Model unavailable to this key");
const response = await fetch(base + "/chat/completions", {
  method: "POST", headers, signal: AbortSignal.timeout(60000),
  body: JSON.stringify({"model":"gemini-3.1-pro-preview","messages":[{"role":"user","content":"Follow this instruction: Return three items; if data is absent, write unknown. Data: no cost is stated; the deadline is 8 days. Return deadline, cost and the main question for the author."}],"max_tokens":512,"stream":false})
});
if (!response.ok) throw new Error("Generation HTTP " + response.status);
const result = await response.json();
const choice = result.choices?.[0];
if (choice?.finish_reason !== "stop" || !choice?.message?.content) throw new Error("Incomplete or empty response");
console.log(choice.message.content);
console.log(result.usage);

The examples use basic fields from the published API contract.

Gemini 3.1 Pro Preview in n8n: HTTP Request

1. Create an HTTP Request with method POST and URL https://gateway.api429.com/v1/chat/completions.
2. Store the Bearer key in credentials; add Content-Type: application/json. Do not put the key in an exported workflow example.
3. Send the JSON from curl: the exact model gemini-3.1-pro-preview, messages, max_tokens and stream=false.
4. After the HTTP node, check choices, finish_reason and the response content before writing the result to your production system.

HTTP Request documentation.

Alternatives to Gemini 3.1 Pro Preview: similar models and prices

Compare them on the same task. Prices apply to a short text request; see the catalog for full pricing.

Version and release date

Manufacturer API release date, Google: Feb 19, 2026. The exact predecessor has not been established in the reviewed sources.

Frequently asked questions

Sources and review

• ai.google.dev/gemini-api/docs/models/gemini-3.1-pro-preview
• ai.google.dev/gemini-api/docs/pricing
• ai.google.dev/gemini-api/docs/deprecations
• gateway.api429.com/api/public/openapi.json

Editorial review: Oct 24, 2026, 6:11 AM UTC. Pricing and general calculator · Getting started · Compare the family: Gemini