# Google Gemini 3.1 Flash Image — Text To Image

> Leverage the Nano banana api for sub-second visual inference and 1M context. Build high-speed vision agents and OCR tools with low-latency multimodal power.

## Overview

- **Endpoint**: `POST https://gptproto.com/api/v3/google/gemini-3.1-flash-image/text-to-image`
- **Result URL**: `GET https://gptproto.com/api/v3/predictions/{result_id}/result` — the submit response also returns the authoritative URL in `data.urls.get`
- **Model ID**: `gemini-3.1-flash-image`
- **Vendor**: Google
- **Scene**: `text-to-image`
- **Category**: text-to-image
- **Modalities**: input text → output image
- **Playground**: https://gptproto.com/model/google/gemini-3.1-flash-image
- **API documentation**: https://docs.gptproto.com
- **Other scenes of this model**: `image-edit` — same auth, different endpoint path and input schema

## Authentication

Every request needs a GPTProto API key in the `Authorization` header. Create one at https://gptproto.com/dashboard/api-key, then export it:

```bash
export GPTPROTO_API_KEY="your-api-key"
```

Header: `Authorization: Bearer $GPTPROTO_API_KEY` (plus `Content-Type: application/json` on POST).

## Pricing

Platform price by tier (USD, already includes the GPTProto discount):

- **1k** — $0.0402 per run
- **2k** — $0.0606 per run
- **4k** — $0.0906 per run

Price range: $0.0402 – $0.0906 per generation.

Prices may change. The model page always shows the live price: https://gptproto.com/model/google/gemini-3.1-flash-image

## API Information

The API is asynchronous: POST the endpoint to create a prediction, then poll its result URL until `status` is `completed` or `failed`.

### Input Schema

The endpoint accepts the following JSON body parameters:

- **`prompt`** (`string`, _required_):
  The positive prompt for the generation.

- **`aspect_ratio`** (`enum`, _optional_):
  The aspect ratio of the generated media.
  - Default: `16:9`
  - Options: 1:1, 3:2, 2:3, 3:4, 4:3, 4:5, 5:4, 9:16, 16:9, 21:9

- **`size`** (`enum`, _optional_):
  The size of the output image.
  - Default: `1k`
  - Options: 1k, 2k, 4k

- **`output_formart`** (`enum`, _optional_):
  The format of the output image.
  - Default: `png`
  - Options: png, jpeg

- **`enable_base64_output`** (`enum`, _optional_):
  If enabled, the output will be encoded into a BASE64 string instead of a URL. This property is only available through the API.
  - Default: `false`
  - Options: true, false

- **`enable_sync_mode`** (`enum`, _optional_):
  If set to true, the function will wait for the result to be generated and uploaded before returning the response. It allows you to get the result directly in the response. This property is only available through the API.
  - Default: `false`
  - Options: true, false

**Required Parameters Example**:

```json
{
  "prompt": "A tiny origami fox sailing a teacup across a moonlit puddle"
}
```

**Full Example**:

```json
{
  "prompt": "A tiny origami fox sailing a teacup across a moonlit puddle",
  "aspect_ratio": "16:9",
  "size": "1k",
  "output_formart": "png",
  "enable_base64_output": false,
  "enable_sync_mode": false
}
```

### Output Schema

Both submit and poll return the same envelope:

- **`data.id`** (`string`): Prediction id. Use it as `result_id` when polling for the result.
- **`data.status`** (`string`): One of `created`, `running`, `completed`, `failed`. See Status Values below.
- **`data.outputs`** (`array of string`): Generated files. Empty until `status` is `completed`; then it holds the output URLs (or base64 strings when the model exposes a base64 option).
- **`data.urls.get`** (`string`): Authoritative result URL for this prediction. Prefer it over building the poll URL yourself.
- **`data.error`** (`string | null`): Failure reason when `status` is `failed`, otherwise `null`.
- **`data.executionTime`** (`integer`): Total processing time in milliseconds.
- **`data.timings.inference`** (`integer`): Model inference time in milliseconds.
- **`data.hasNsfwContents`** (`array of boolean`): Per-output moderation flags.
- **`message`** (`string`): `success` on a normal response, otherwise the error message.
- **`code`** (`integer`): Business status code. `200` means the request was accepted.

**Example Response — submit (task accepted)**:

```json
{
  "data": {
    "id": "pred_example_01",
    "model": "gemini-3.1-flash-image",
    "outputs": [],
    "urls": {
      "get": "https://gptproto.com/api/v3/predictions/pred_example_01/result"
    },
    "hasNsfwContents": [],
    "status": "created",
    "createdAt": "2026-01-01T12:00:00Z",
    "executionTime": 0,
    "timings": {
      "inference": 0
    }
  },
  "message": "success",
  "code": 200
}
```

**Example Response — poll (completed)**:

```json
{
  "data": {
    "id": "pred_example_01",
    "model": "gemini-3.1-flash-image",
    "outputs": [
      "https://oss-us.gptproto.com/example/output.png"
    ],
    "urls": {
      "get": "https://gptproto.com/api/v3/predictions/pred_example_01/result"
    },
    "status": "completed",
    "error": null,
    "executionTime": 12345,
    "timings": {
      "inference": 12000
    },
    "has_nsfw_contents": [],
    "created_at": "2026-01-01T12:00:00Z"
  },
  "message": "success",
  "code": 200
}
```

### Status Values

- `created` — Task accepted. Use `data.id` as `result_id` for polling.
- `running` — Generation is in progress. Keep polling.
- `completed` — Finished successfully. Generated files are in `data.outputs`.
- `failed` — Generation failed. Read `data.error` for the reason.

## Usage Examples

### 1. Submit a request

```bash
curl --request POST "https://gptproto.com/api/v3/google/gemini-3.1-flash-image/text-to-image" \
  --header "Authorization: Bearer $GPTPROTO_API_KEY" \
  --header "Content-Type: application/json" \
  --data '{
    "prompt": "A tiny origami fox sailing a teacup across a moonlit puddle",
    "aspect_ratio": "16:9",
    "size": "1k",
    "output_formart": "png",
    "enable_base64_output": false,
    "enable_sync_mode": false
  }'
```

```python
import os
import requests

url = "https://gptproto.com/api/v3/google/gemini-3.1-flash-image/text-to-image"
headers = {
  "Authorization": f"Bearer {os.environ['GPTPROTO_API_KEY']}",
  "Content-Type": "application/json"
}
payload = {
  "prompt": "A tiny origami fox sailing a teacup across a moonlit puddle",
  "aspect_ratio": "16:9",
  "size": "1k",
  "output_formart": "png",
  "enable_base64_output": False,
  "enable_sync_mode": False
}

response = requests.request("POST", url, headers=headers, json=payload)
print(response.json())
```

```typescript
const response = await fetch("https://gptproto.com/api/v3/google/gemini-3.1-flash-image/text-to-image", {
  method: "POST",
  headers: {
    "Authorization": `Bearer ${process.env.GPTPROTO_API_KEY}`,
    "Content-Type": "application/json",
  },
  body: JSON.stringify({
    prompt: "A tiny origami fox sailing a teacup across a moonlit puddle",
    aspect_ratio: "16:9",
    size: "1k",
    output_formart: "png",
    enable_base64_output: false,
    enable_sync_mode: false,
  }),
});

const data = await response.json();
console.log(data);
```

### 2. Poll until the task finishes

Replace `YOUR_RESULT_ID` with `data.id` from the submit response (or call `data.urls.get` directly), and keep polling every 1–3 seconds while `status` is `created` or `running`.

```bash
result_id="YOUR_RESULT_ID"

curl --request GET "https://gptproto.com/api/v3/predictions/$result_id/result" \
  --header "Authorization: Bearer $GPTPROTO_API_KEY"
```

```python
import os
import requests

result_id = "YOUR_RESULT_ID"
url = f"https://gptproto.com/api/v3/predictions/{result_id}/result"
headers = {
  "Authorization": f"Bearer {os.environ['GPTPROTO_API_KEY']}"
}
response = requests.request("GET", url, headers=headers)
print(response.json())
```

```typescript
const result_id = "YOUR_RESULT_ID";
const response = await fetch(`https://gptproto.com/api/v3/predictions/${result_id}/result`, {
  method: "GET",
  headers: {
    "Authorization": `Bearer ${process.env.GPTPROTO_API_KEY}`,
  },
});

const data = await response.json();
console.log(data);
```

## Example Prompts

- an epic sci-fi movie poster, a lone astronaut standing on a vast desert planet, a gigantic ringed planet rising in the sky, dramatic sunset lighting, blowing sand, cinematic composition, IMAX scale, photorealistic, space for title at the top, film poster design, ultra detailed
- "resolution": "8K ultra high definition", "style": "hyper - realistic food illustration with editorial infographic overlays", "lighting": "soft directional key light, subtle rimlight' "scene_description": "A vertical stack of cake slices floating above a plate against soft pink g…
- A beautiful anime scene in the style of Studio Ghibli. A young girl in a simple summer dress sits alone on a weathered wooden bench at a rural bus stop in the Japanese countryside. It's late afternoon, and the sky is a soft orange. The bus stop is surrounded by lush, overgrown gr…

## HTTP Status Codes

- `400` — malformed body, a parameter or value this model does not accept, or input blocked by the provider's content moderation
- `401` — missing or invalid API key
- `403` — insufficient credits
- `413` — request body too large
- `429` — rate limited; retry with backoff
- `500` — An internal server error occurred
- `502` — An internal server error occurred
- `504` — Gateway timeout — upstream service did not respond in time; retry later

## Additional Resources

- [Model playground](https://gptproto.com/model/google/gemini-3.1-flash-image)
- [API documentation](https://docs.gptproto.com)
- [All models](https://gptproto.com/model)
- [API keys](https://gptproto.com/dashboard/api-key)
- [Platform overview for LLMs](https://gptproto.com/llm-full.txt)
- Any other model: `https://gptproto.com/model/{vendor}/{model}/{scene}/llms.txt`