> ## Documentation Index
> Fetch the complete documentation index at: https://mintlify.com/firebase/genkit/llms.txt
> Use this file to discover all available pages before exploring further.

# Google GenAI Plugin

> Use Google AI (Gemini) and Vertex AI models with Genkit

# Google GenAI Plugin

The `@genkit-ai/google-genai` plugin provides a unified interface to connect with Google's generative AI models, offering access through both the **Gemini Developer API** and **Vertex AI**. It replaces the previous `googleAI` and `vertexAI` plugins.

## Installation

```bash theme={null}
npm install @genkit-ai/google-genai
```

## Configuration

This unified plugin exports two main initializers:

* **`googleAI`**: Access models via the Gemini Developer API using API key authentication
* **`vertexAI`**: Access models via Google Cloud Vertex AI

### Using Gemini Developer API (`googleAI`)

Ideal for quick prototyping and access to models available in Google AI Studio.

**Authentication:** Requires a Google AI API Key from [Google AI Studio](https://aistudio.google.com/apikey). Provide the key via `GEMINI_API_KEY` or `GOOGLE_API_KEY` environment variables, or pass it in the plugin configuration.

```typescript theme={null}
import { genkit } from 'genkit';
import { googleAI } from '@genkit-ai/google-genai';

const ai = genkit({
  plugins: [
    googleAI(),
    // Or with an explicit API key:
    // googleAI({ apiKey: 'your-api-key' }),
  ],
});
```

### Using Vertex AI (`vertexAI`)

Suitable for applications leveraging Google Cloud's AI infrastructure.

**Authentication Methods:**

* **Application Default Credentials (ADC):** Standard method for production. Uses credentials from the environment (service account on GCP, user credentials from `gcloud auth application-default login` locally). Requires a Google Cloud Project with billing and Vertex AI API enabled.

* **Vertex AI Express Mode:** Streamlined way to try Vertex AI features using just an API key, without billing setup. Ideal for quick experimentation with generous free tier quotas. [Learn more about Express Mode](https://cloud.google.com/vertex-ai/generative-ai/docs/start/express-mode/overview).

```typescript theme={null}
import { genkit } from 'genkit';
import { vertexAI } from '@genkit-ai/google-genai';

const ai = genkit({
  plugins: [
    // Using Application Default Credentials (Recommended for full features)
    vertexAI({ location: 'us-central1' }), // Regional endpoint
    // vertexAI({ location: 'global' }),      // Global endpoint

    // OR

    // Using Vertex AI Express Mode (Easy to start, some limitations)
    // vertexAI({ apiKey: process.env.VERTEX_EXPRESS_API_KEY }),
  ],
});
```

**Note:** When using Express Mode, don't provide `projectId` and `location` in the plugin config.

### Using Both Google AI and Vertex AI

You can configure both plugins to access models or features from both services:

```typescript theme={null}
import { genkit } from 'genkit';
import { googleAI, vertexAI } from '@genkit-ai/google-genai';

const ai = genkit({
  plugins: [
    googleAI(),
    vertexAI(),
  ],
});
```

## Available Models

### Gemini Models

* `gemini-2.5-flash` - Fast, efficient model for most tasks
* `gemini-2.5-pro` - Advanced reasoning and complex tasks
* `gemini-1.5-flash` - Previous generation fast model
* `gemini-1.5-pro` - Previous generation advanced model

### Image Generation

* `imagen-3.0-generate-002` - High-quality image generation

### Embeddings

* `gemini-embedding-001` - Text embeddings (Google AI)
* `text-embedding-005` - Text embeddings (Vertex AI)

### Music Generation (Vertex AI Only)

* `lyria-002` - AI music generation

## Usage Examples

### Text Generation with Google AI

```typescript theme={null}
import { genkit } from 'genkit';
import { googleAI } from '@genkit-ai/google-genai';

const ai = genkit({
  plugins: [googleAI()],
});

const response = await ai.generate({
  model: googleAI.model('gemini-2.5-flash'),
  prompt: 'Tell me something interesting about Google AI.',
});

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

### Text Generation with Vertex AI

```typescript theme={null}
import { genkit } from 'genkit';
import { vertexAI } from '@genkit-ai/google-genai';

const ai = genkit({
  plugins: [vertexAI()],
});

const response = await ai.generate({
  model: vertexAI.model('gemini-2.5-pro'),
  prompt: 'Explain Vertex AI in simple terms.',
});

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

### Text Embedding

**With Google AI:**

```typescript theme={null}
import { genkit } from 'genkit';
import { googleAI } from '@genkit-ai/google-genai';

const ai = genkit({
  plugins: [googleAI()],
});

const embeddings = await ai.embed({
  embedder: googleAI.embedder('gemini-embedding-001'),
  content: 'Embed this text.',
});
```

**With Vertex AI:**

```typescript theme={null}
import { genkit } from 'genkit';
import { vertexAI } from '@genkit-ai/google-genai';

const ai = genkit({
  plugins: [vertexAI()],
});

const embeddings = await ai.embed({
  embedder: vertexAI.embedder('text-embedding-005'),
  content: 'Embed this text.',
});
```

### Image Generation (Imagen)

**With Google AI:**

```typescript theme={null}
import { genkit } from 'genkit';
import { googleAI } from '@genkit-ai/google-genai';

const ai = genkit({
  plugins: [googleAI()],
});

const response = await ai.generate({
  model: googleAI.model('imagen-3.0-generate-002'),
  prompt: 'A beautiful watercolor painting of a castle in the mountains.',
});

const generatedImage = response.media();
```

**With Vertex AI:**

```typescript theme={null}
import { genkit } from 'genkit';
import { vertexAI } from '@genkit-ai/google-genai';

const ai = genkit({
  plugins: [vertexAI()],
});

const response = await ai.generate({
  model: vertexAI.model('imagen-3.0-generate-002'),
  prompt: 'A beautiful watercolor painting of a castle in the mountains.',
});

const generatedImage = response.media();
```

### Music Generation (Lyria - Vertex AI Only)

```typescript theme={null}
import { genkit } from 'genkit';
import { vertexAI } from '@genkit-ai/google-genai';

const ai = genkit({
  plugins: [vertexAI()],
});

const response = await ai.generate({
  model: vertexAI.model('lyria-002'),
  prompt: 'A relaxing, instrumental piano track.',
});

const generatedAudio = response.media();
```

## Key Differences

### Google AI (`googleAI`)

* Easier setup for smaller projects
* Great for prototyping with Google AI Studio
* Uses API keys for authentication
* Access to Gemini and Imagen models

### Vertex AI (`vertexAI`)

* Enterprise-ready with Google Cloud IAM
* Integrates with other Vertex AI services
* Broader range of models and features
* Supports Lyria music generation
* Fine-tuning capabilities
* Robust governance and compliance
* Express Mode for easy experimentation

## Links

* [Google AI Studio](https://aistudio.google.com/)
* [Vertex AI](https://cloud.google.com/vertex-ai)
* [Vertex AI Express Mode](https://cloud.google.com/vertex-ai/generative-ai/docs/start/express-mode/overview)
* [Source Code](https://github.com/firebase/genkit/tree/main/js/plugins/google-genai)