Prerequisites
You need a Google account and a free Google AI Studio API key. Sign up at aistudio.google.com.
Install the SDK
```
npm install @google/generative-ai
```
Your First Request
```javascript
import { GoogleGenerativeAI } from "@google/generative-ai";
const genAI = new GoogleGenerativeAI(process.env.GEMINI_API_KEY);
const model = genAI.getGenerativeModel({ model: "gemini-2.5-flash" });
const result = await model.generateContent("Explain quantum entanglement simply");
console.log(result.response.text());
```
Model Selection Guide
**gemini-2.5-flash** — Best for most use cases: fast, cheap, capable. Use this first.
**gemini-2.5-pro** — Complex reasoning, long documents, difficult coding tasks. Costs more.
**gemini-2.5-flash-lite** — Ultra-fast, ultra-cheap. Ideal for classification, summarization, batch jobs.
Free Tier Limits
Google AI Studio free tier: 15 RPM, 1 million tokens/day. No credit card required.