VARIANT · Google / Gemini

gemini-3.1-pro-preview API

Google / Gemini

Use gemini-3.1-pro-preview from the Gemini family via RunAPI. Per-call pricing, no subscription, and failed generations are never charged.

Operational · text · Commercial OK

runapi.ai

# Base URL
https://runapi.ai

# Endpoints
POST /v1/chat/completions
POST /v1beta/models/*:streamGenerateContent

curl https://runapi.ai/v1/chat/completions \
  -H "Authorization: Bearer $RUNAPI_KEY" \
  -H "Content-Type: application/json" \
  -d '{
  "model": "gemini-3.1-pro-preview",
  "messages": [
    {
      "role": "user",
      "content": "Analyze this codebase and suggest three performance improvements with before/after examples."
    }
  ]
}'

from openai import OpenAI

client = OpenAI(
    base_url="https://runapi.ai/v1",
    api_key="your-runapi-key"
)

response = client.chat.completions.create(
    model="gemini-3.1-pro-preview",
    messages=[{"role": "user", "content": "Analyze this codebase and suggest three performance improvements with before/after examples."}]
)

import OpenAI from "openai";

const client = new OpenAI({
  baseURL: "https://runapi.ai/v1",
  apiKey: "your-runapi-key"
});

const response = await client.chat.completions.create({
  model: "gemini-3.1-pro-preview",
  messages: [{ role: "user", content: "Analyze this codebase and suggest three performance improvements with before/after examples." }]
});

https://runapi.ai /v1/chat/completions /v1beta/models/*:streamGenerateContent

Switch variant

gemini-2.5-flash gemini-2.5-pro gemini-3-flash-preview gemini-3-pro-preview gemini-3.5-flash

OVERVIEW

gemini-3.1-pro-preview targets the sweet spot of quality and cost within the Gemini family. It shares the same API key, request shape, and async task lifecycle as every other RunAPI model — switch to this variant by changing one model ID parameter. Install the Gemini skill to load docs, typed schemas, pricing notes, and setup steps into your coding workspace. Billing is metered per completed request in USD with no subscription or minimum spend, and failed generations are never charged.

Pay-per-call pricing in USD with no subscription
Failed generations are never charged
Streaming when supported by the model
Schema-validated parameters and tool calls
Switch variant by changing one model ID parameter
Unified billing across all models and providers

PRICING

Pricing

Failed generations are not charged

Chat completion

Input $1.00 / 1M tokens

Output $6.00 / 1M tokens

Cache read $0.10

SPEC SHEET

Technical details

Model ID	gemini-3.1-pro-preview
Provider	Google
Modality	text
Task type	synchronous
Billing unit	1K tokens
API endpoint	/v1/chat/completions
Commercial license	Yes — included via API
Status	Operational

SKILLS

Model skill — gemini-3.1-pro-preview

Install the skill once, then use the variant ID from this page while building.

Endpoint	Protocol
/v1/chat/completions	OpenAI compatible
/v1beta/models/*:streamGenerateContent	/v1beta/models/*:streamGenerateContent

HOW IT WORKS

Use gemini-3.1-pro-preview with a model skill

Install

Install the model skill for the %{model} line. The skill loads docs, typed schemas, pricing notes, and setup steps into your coding workspace so your agent has the right context.

Configure

Set the model field to the full model ID shown on this page and configure your RunAPI API key as an environment variable. The same key works across all models and providers.

Call

Use the skill instructions while adding prompt, input, and callback handling to your application. RunAPI routes the request to the provider, manages the async lifecycle, and returns structured JSON.

Receive

Read the task response by polling the task ID, streaming when supported, or handling the webhook callback at your configured URL. Generated outputs are stored and retrievable by task ID.

DIFFERENCES

What's different about gemini-3.1-pro-preview

VS GEMINI-2.5-FLASH

gemini-3.1-pro-preview

Speed/cost optimized; 1M context; older generation baseline

VS GEMINI-2.5-PRO

gemini-3.1-pro-preview

Best reasoning in 2.5 gen; 1M context

VS GEMINI-3-FLASH-PREVIEW

gemini-3.1-pro-preview

gemini-3-flash-preview

USE CASES

Best for

Customer support

Answer customer questions from a private knowledge base, reducing ticket volume.

Document analysis

Draft contract summaries and flag key clauses for attorney review.

Code generation

Auto-generate unit tests, code reviews, and refactoring suggestions in CI.

FAQ

Frequently asked questions about gemini-3.1-pro-preview

Is the model ID stable across versions?

Yes. RunAPI keeps the model ID stable and handles compatible version refreshes without changing your request shape. You do not need to update your code when the provider releases a new compatible version.

What's the rate limit on this variant?

Per-key rate limits scale with your usage tier. The pricing page shows current limits. If you need higher throughput, contact support to discuss tier upgrades.

Can I switch variants later?

Yes. Variant is a parameter in the request. Switch by changing the model ID — no code changes, no re-authentication, no separate billing setup. All variants share the same API key and request shape.

Does it stream?

Where streaming is available, RunAPI streams end-to-end. LLM models support token-level streaming. Media models use async task polling or webhook callbacks for result delivery.

Where do I report quality issues?

Open an issue on the public GitHub repo or email support at [email protected]. Include the task ID and model ID so the team can investigate the specific generation.

Do I need a separate provider account?

No. Your RunAPI API key is enough to access this variant and every other model in the catalog. You do not need accounts with the underlying provider.