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

# Nano Banana2 Image Generation

> Nano Banana2 Image Generation API: Powered by Gemini 3.1 Flash. Only $0.055/image, supports text-to-image + image editing, 4K resolution, compatible with OpenAI SDK and Google native format.

**🆕 Nano Banana2 (Gemini 3.1 Flash) Now Available!**
The new benchmark for value. Usage is identical to Nano Banana Pro.

* **Great Value**: Only **\$0.055/image**, cheaper than Pro
* **4K Quality**: Supports 1K, 2K, 4K resolutions
* **Full Features**: Text-to-image + image editing, compatible with OpenAI SDK and Google native format

## 🎁 Free Trial

Register and get **\$0.5** credit toward Nano Banana2 usage

## 🚀 Live Demo

AI Images - Try instantly, no code required

## Prerequisites

1

Get API Key

Login to [YeLIn AI console](https://api.yelinai.com) to get your API key

2

Configure Billing Mode

Edit token settings and select one of these billing modes (same price):

* **Pay-per-use Priority** (Recommended): Use balance first, auto-switch when insufficient
* **Pay-per-use**: Direct charge per request, best for strict budget control

Both modes have **identical pricing** at \$0.055/image, only the billing method differs.

<Note>
  请在 **Console** 查看对应界面截图。
</Note>

API calls will fail without proper billing configuration. Complete this setup first!

## Model Overview

**Nano Banana2** is LaoZhang API’s custom name for Google’s **Gemini 3.1 Flash Image Preview** (`gemini-3.1-flash-image-preview`) model. Built on the latest Gemini 3.1 Flash architecture, it delivers high-quality output with better value.
**Nano Banana2 usage is identical to [Nano Banana Pro](/en/api-capabilities/nano-banana-pro-image)** - just replace the model name with `gemini-3.1-flash-image-preview`.

## 📋 Nano Banana Model Comparison

| Model               | Model ID                         | Billing | LaoZhang API Price | Resolution | Speed | Highlight                              |
| ------------------- | -------------------------------- | ------- | ------------------ | ---------- | ----- | -------------------------------------- |
| **Nano Banana Pro** | `gemini-3-pro-image-preview`     | Per-use | \$0.09/image       | 1K/2K/4K   | \~10s | Most intelligent, complex instructions |
| **Nano Banana2**    | `gemini-3.1-flash-image-preview` | Per-use | \$0.055/image      | 1K/2K/4K   | \~10s | Best value, high quality               |
| **Nano Banana**     | `gemini-2.5-flash-image`         | Per-use | \$0.025/image      | 1K (fixed) | \~10s | Basic, stable & reliable               |

💡 **How to Choose?**

* **Ultimate quality & complex instructions**: Choose Nano Banana Pro (\$0.09/image)
* **Best value for advanced use**: Choose **Nano Banana2** (\$0.055/image)
* **Budget-conscious, basic needs**: Choose Nano Banana Standard (\$0.025/image)

## 🚀 Quick Start: OpenAI Compatible Mode

### Curl Example

```
curl -X POST "https://api.yelinai.com/v1/chat/completions" \
     -H "Authorization: Bearer $API_KEY" \
     -H "Content-Type: application/json" \
     -d '{
    "model": "gemini-3.1-flash-image-preview",
    "stream": false,
    "messages": [
        {
            "role": "user",
            "content": "a beautiful sunset over mountains"
        }
    ]
}'
```

### Python SDK Example

```
from openai import OpenAI
import base64
import re

client = OpenAI(
    api_key="sk-YOUR_API_KEY",
    base_url="https://api.yelinai.com/v1"
)

response = client.chat.completions.create(
    model="gemini-3.1-flash-image-preview",
    messages=[
        {
            "role": "user",
            "content": "a beautiful sunset over mountains"
        }
    ]
)

# Extract base64 image data
content = response.choices[0].message.content
match = re.search(r'!\[.*?\]\((data:image/png;base64,.*?)\)', content)

if match:
    base64_data = match.group(1).split(',')[1]
    image_data = base64.b64decode(base64_data)

    with open('output.png', 'wb') as f:
        f.write(image_data)
    print("✅ Image saved: output.png")
```

## 🎨 Image Editing

Nano Banana2 also supports image editing, with usage identical to Pro. Simply include reference images and editing instructions in your request, using model name `gemini-3.1-flash-image-preview`.

```
# Image editing example (OpenAI compatible mode)
response = client.chat.completions.create(
    model="gemini-3.1-flash-image-preview",
    messages=[{
        "role": "user",
        "content": [
            {"type": "text", "text": "Transform this image into Van Gogh Starry Night style"},
            {"type": "image_url", "image_url": {"url": "https://example.com/your-image.jpg"}}
        ]
    }]
)
```

For more image editing features (multi-image fusion, 4K output, Google native format, etc.), see the [Nano Banana Pro Image Editing docs](/en/api-capabilities/nano-banana-pro-image-edit) and replace the model name with `gemini-3.1-flash-image-preview`.

## 📖 Complete Usage Guide

**Nano Banana2 API calls are identical to Nano Banana Pro**, including OpenAI compatible mode and Google native format. Simply replace the model name from `gemini-3-pro-image-preview` to `gemini-3.1-flash-image-preview` - no other code changes needed.

## Pro Text-to-Image Guide

4K resolution, Google native format, multiple aspect ratios, complete code examples

## Pro Image Editing Guide

Style transfer, multi-image fusion, 4K HD editing, URL input method

## Token Management

Create and manage your API tokens

## Pricing

View detailed pricing and billing information

## ❓ FAQ

What's the difference between Nano Banana2 and Nano Banana Pro?

| Feature    | Nano Banana Pro              | Nano Banana2                     |
| ---------- | ---------------------------- | -------------------------------- |
| Model      | `gemini-3-pro-image-preview` | `gemini-3.1-flash-image-preview` |
| Technology | Gemini 3 Pro                 | Gemini 3.1 Flash                 |
| Resolution | 1K/2K/4K                     | 1K/2K/4K                         |
| Price      | \$0.09/image                 | \$0.055/image                    |
| API Usage  | Identical                    | Identical                        |

Both share the same API interface. Banana2 is based on Gemini 3.1 Flash architecture with a more affordable price point.

How to migrate from Pro to Banana2?

Just change one line of code: replace the model name from `gemini-3-pro-image-preview` to `gemini-3.1-flash-image-preview`. Everything else stays the same.

Does Banana2 support Google native format?

**Yes, fully supported!** Use this endpoint:

```
https://api.yelinai.com/v1beta/models/gemini-3.1-flash-image-preview:generateContent
```

Supports custom aspect ratios (10 options) and resolutions (1K/2K/4K), same usage as Pro.

Does Banana2 support image editing?

**Yes!** Full text-to-image and image editing features. See the [Pro Image Editing docs](/en/api-capabilities/nano-banana-pro-image-edit) for details.

***

## 📝 Changelog

2026-02: Nano Banana2 Launched

**🆕 Nano Banana2 Released**

* Based on Gemini 3.1 Flash architecture
* Pricing has been synced to the current page rate while keeping the same value positioning
* Usage identical to Nano Banana Pro
* Supports text-to-image, image editing, 4K resolution