Google Gemini API: Complete Guide and Integration

Google Gemini is Google DeepMind's family of multimodal AI models. The Gemini API offers an extremely generous free tier (1.5M tokens/day) to integrate AI into your projects.

Key Features

• Free API: 15 requests/min, 1.5M tokens/day, no credit card required
• Models: Gemini Pro (balanced), Flash (fast), Ultra (powerful)
• Multimodal: text + image + video + code
• Large context: up to 1 million tokens
• Official SDK: @google/generative-ai (Node.js)

Available Models

Model Selection Guide

Getting Started with Gemini API

1. Obtain Your API Key

1. Visit Google AI Studio
2. Sign in with your Google account
3. Click "Get API key" and create a new key
4. Store it securely (never commit to version control)

2. Install the SDK

npm install @google/generative-ai

3. Basic Text Generation

import { GoogleGenerativeAI } from "@google/generative-ai";

const genAI = new GoogleGenerativeAI(process.env.GEMINI_API_KEY);
const model = genAI.getGenerativeModel({ model: "gemini-1.5-flash" });

const prompt = "Explain how AI works in simple terms";
const result = await model.generateContent(prompt);
const response = result.response;
console.log(response.text());

4. Multimodal Input (Text + Image)

import { GoogleGenerativeAI } from "@google/generative-ai";
import fs from "fs";

const genAI = new GoogleGenerativeAI(process.env.GEMINI_API_KEY);
const model = genAI.getGenerativeModel({ model: "gemini-1.5-pro" });

const imageData = fs.readFileSync("image.jpg");
const base64Image = imageData.toString("base64");

const result = await model.generateContent([
  { text: "Describe what's in this image in detail" },
  {
    inlineData: {
      mimeType: "image/jpeg",
      data: base64Image
    }
  }
]);

console.log(result.response.text());

5. Streaming Responses

const model = genAI.getGenerativeModel({ model: "gemini-1.5-flash" });
const prompt = "Write a short story about a robot";

const result = await model.generateContentStream(prompt);

for await (const chunk of result.stream) {
  const chunkText = chunk.text();
  process.stdout.write(chunkText);
}

Use Cases

1. Content Generation and Code

• Article writing: Generate blog posts, documentation, marketing copy
• Code generation: Create functions, debug code, explain algorithms
• Creative writing: Stories, poetry, dialogue
• Summarization: Condense long documents into key points

2. Image and Document Analysis

• OCR alternative: Extract text from images and PDFs
• Visual understanding: Describe scenes, identify objects
• Document parsing: Extract structured data from invoices, receipts
• Accessibility: Generate alt text for images

3. Chatbots and Conversational AI

• Customer support: Automated helpdesk with context retention
• Virtual assistants: Task automation and information retrieval
• Interactive tutorials: Adaptive learning experiences
• Multi-turn conversations: Context-aware dialogue

4. Multilingual Translation

• 100+ languages: Including Arabic, French, English
• Context-aware: Better than literal translation
• Tone preservation: Maintains formality and style
• Code comments: Translate documentation and comments

5. RAG (Retrieval-Augmented Generation)

Combine Gemini with your own data for accurate, context-specific responses:

Pricing and Limits

Free Tier

Paid Tier (Pay-as-you-go)

For production applications exceeding free tier limits:

• Gemini Flash: $0.075 per 1M input tokens, $0.30 per 1M output tokens
• Gemini Pro: $1.25 per 1M input tokens, $5.00 per 1M output tokens
• No minimum: Pay only for what you use
• Higher rate limits: 1000+ requests per minute available

Best Practices

Security

• Never expose API keys: Use environment variables, never commit keys
• Server-side only: Don't call API from client-side JavaScript
• Rate limiting: Implement your own rate limiting for user-facing features
• Content filtering: Use Gemini's safety settings to filter inappropriate content

Optimization

• Caching: Cache common responses to reduce API calls
• Model selection: Use Flash for simple tasks, Pro for complex ones
• Prompt optimization: Clear, specific prompts produce better results
• Streaming: Use streaming for better perceived performance

Comparison with Other APIs

Additional Resources

• Official Gemini API Documentation
• Google AI Studio: Test prompts and get API keys
• Artificial Intelligence Expertise: our AI services
• All our publications: tech guides and news

Article published on 2025-12-06. Complete guide to Google Gemini API integration with examples and best practices.