Gemini 3.1 Flash Image Preview

gemini-3.1-flash-image-preview is the Gemini 3.1 Flash image model for generation and editing. Use the canonical Gemini model id and pass an aspect ratio through size.

API surface

Operation	Endpoint	Mode
Image generation	POST /v1/images/generations	Sync
Image generation task	POST /v1/async/images/generations	Async
Image editing	POST /v1/images/edits	Sync
Image editing task	POST /v1/async/images/edits	Async

Pricing

Credits

Model id	Output tier	Credits / image
gemini-3.1-flash-image-preview-512	512px	4
gemini-3.1-flash-image-preview	1K (1024px)	4
gemini-3.1-flash-image-preview-2k	2K (2048px)	6
gemini-3.1-flash-image-preview-4k	4K (4096px)	8

Request fields

This model uses the same OpenAI-compatible image fields as the rest of Pixapi.

Field	Type	Required	Description
model	string	Yes	Use gemini-3.1-flash-image-preview.
prompt	string	Yes	Describe the desired image or edit.
image	string or string[]	Required for edits	Input image URL, or an array of image URLs when multiple references are supported.
n	number	No	Number of images to return. Only 1 is currently supported.
size	string	No	Output aspect ratio: 1:1, 16:9, 9:16, 4:3, 3:4, 2:3, 3:2, 4:5, 5:4, 21:9, 1:4, 4:1, 8:1, or 1:8.

Example

cURL

curl https://api.pixapi.ai/v1/images/generations \
  -H "Authorization: Bearer $PIXAPI_KEY" \
  -H "Content-Type: application/json" \
  -d '{
  "model": "gemini-3.1-flash-image-preview",
  "prompt": "A polished product photo of a ceramic coffee cup",
  "n": 1,
  "size": "1:1"
}'

Python

import os
import requests

response = requests.post(
    "https://api.pixapi.ai/v1/images/generations",
    headers={
        "Authorization": f"Bearer {os.environ['PIXAPI_KEY']}",
        "Content-Type": "application/json",
    },
    json={
    "model": "gemini-3.1-flash-image-preview",
    "prompt": "A polished product photo of a ceramic coffee cup",
    "n": 1,
    "size": "1:1"
},
)
response.raise_for_status()
print(response.json())

JavaScript

const response = await fetch('https://api.pixapi.ai/v1/images/generations', {
  method: 'POST',
  headers: {
    Authorization: `Bearer ${process.env.PIXAPI_KEY}`,
    'Content-Type': 'application/json',
  },
  body: JSON.stringify({
  "model": "gemini-3.1-flash-image-preview",
  "prompt": "A polished product photo of a ceramic coffee cup",
  "n": 1,
  "size": "1:1"
}),
});

if (!response.ok) {
  throw new Error(await response.text());
}

console.log(await response.json());

Go

package main

import (
  "bytes"
  "fmt"
  "io"
  "net/http"
  "os"
)

func main() {
  body := []byte(`{
  "model": "gemini-3.1-flash-image-preview",
  "prompt": "A polished product photo of a ceramic coffee cup",
  "n": 1,
  "size": "1:1"
}`)

  req, err := http.NewRequest(
    "POST",
    "https://api.pixapi.ai/v1/images/generations",
    bytes.NewBuffer(body),
  )
  if err != nil {
    panic(err)
  }
  req.Header.Set("Authorization", "Bearer "+os.Getenv("PIXAPI_KEY"))
  req.Header.Set("Content-Type", "application/json")

  resp, err := http.DefaultClient.Do(req)
  if err != nil {
    panic(err)
  }
  defer resp.Body.Close()

  result, _ := io.ReadAll(resp.Body)
  fmt.Println(string(result))
}

For the shared response shape and edit upload example, see the API Reference.