Nano Banana 2.1 API: Image Generation & Editing

Overview

Nano Banana 2.1 supports text-to-image generation and reference-guided image editing. It accepts flexible aspect ratios, up to 10 reference images in image-to-image mode, and 1K, 2K, or 4K output.

Capability	Value
Model ID	`nano-banana-2-1`
Modes	`text-to-image`, `image-to-image`
Prompt length	1-20,000 characters
Reference images	Required for `image-to-image`; up to 10 URLs
Aspect ratios	`auto`, `1:1`, `1:4`, `4:1`, `1:8`, `8:1`, `2:3`, `3:2`, `3:4`, `4:3`, `4:5`, `5:4`, `9:16`, `16:9`, `21:9`
Resolution tiers	`1K`, `2K`, `4K`
Output formats	`jpg`, `jpeg`, `png`

Endpoint and authentication

Base URL:

https://api.apixo.ai/api/v1

Method	Endpoint	Purpose
`POST`	`/generateTask/nano-banana-2-1`	Submit a generation task
`GET`	`/statusTask/nano-banana-2-1?taskId={taskId}`	Poll task status and retrieve results

All requests require your APIXO API key:

Authorization: Bearer YOUR_API_KEY

Submit requests also require:

Content-Type: application/json

Copy-paste async quickstart

This request submits a text-to-image task and returns a taskId.

curl -X POST "https://api.apixo.ai/api/v1/generateTask/nano-banana-2-1" \
  -H "Authorization: Bearer YOUR_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "request_type": "async",
    "input": {
      "mode": "text-to-image",
      "prompt": "A cinematic banana-shaped spaceship above a neon city",
      "aspect_ratio": "16:9",
      "resolution": "2K",
      "output_format": "jpg"
    }
  }'

Successful response:

{
  "code": 200,
  "message": "success",
  "data": {
    "taskId": "task_12345678"
  }
}

Save the taskId; you need it to poll for the final result.

Poll for result

curl -X GET "https://api.apixo.ai/api/v1/statusTask/nano-banana-2-1?taskId=task_12345678" \
  -H "Authorization: Bearer YOUR_API_KEY"

Processing response:

{
  "code": 200,
  "message": "success",
  "data": {
    "taskId": "task_12345678",
    "state": "processing",
    "createTime": 1791469979361
  }
}

Success response:

{
  "code": 200,
  "message": "success",
  "data": {
    "taskId": "task_12345678",
    "state": "success",
    "resultJson": "{\"resultUrls\":[\"https://file.apixo.ai/xxx.jpg\"]}",
    "createTime": 1791469979361,
    "completeTime": 1791470020749,
    "costTime": 41388
  }
}

Failed response:

{
  "code": 200,
  "message": "success",
  "data": {
    "taskId": "task_12345678",
    "state": "failed",
    "failCode": "SensitiveContent",
    "failMsg": "Content violates safety policy, please adjust the prompt",
    "createTime": 1791469979361,
    "completeTime": 1791469990132
  }
}

Parse resultJson after state becomes success:

const payload = JSON.parse(data.resultJson);
const imageUrls = payload.resultUrls;

Request body

Text-to-image

{
  "request_type": "async",
  "input": {
    "mode": "text-to-image",
    "prompt": "A warm editorial portrait with soft window light",
    "aspect_ratio": "4:5",
    "resolution": "2K",
    "output_format": "png"
  }
}

Image-to-image

{
  "request_type": "async",
  "input": {
    "mode": "image-to-image",
    "prompt": "Keep the subject and change the background to a snowy mountain",
    "image_urls": [
      "https://example.com/reference.png"
    ],
    "aspect_ratio": "3:2",
    "resolution": "4K",
    "output_format": "jpg"
  }
}

Parameters

string

default:"async"

Result delivery mode. Use async for polling with statusTask, or callback for webhook delivery.

string

Required when request_type is callback. Must be a public HTTPS URL that can receive the final task payload. See Webhooks.

object

required

Nano Banana 2.1 input parameters.

Show properties

string

required

Generation mode. Supported values: text-to-image, image-to-image.

string

required

Text prompt describing the desired image or edit. Leading and trailing whitespace is ignored for validation. Supports 1-20,000 characters.

string[]

Reference image URLs. Required for image-to-image; provide 1-10 public, directly fetchable image URLs. Optional in text-to-image mode.

string

default:"1:1"

Output aspect ratio. Supported values: auto, 1:1, 1:4, 4:1, 1:8, 8:1, 2:3, 3:2, 3:4, 4:3, 4:5, 5:4, 9:16, 16:9, 21:9.

string

default:"1K"

Output resolution tier. Supported values: 1K, 2K, 4K. Values are case-insensitive.

string

default:"jpg"

Output image format. Supported values: jpg, jpeg, png. jpeg is accepted as an alias for jpg.

image_urls is required only when mode is image-to-image. When omitted, aspect_ratio, resolution, and output_format default to 1:1, 1K, and jpg.

Response format

Submit task response

POST /generateTask/nano-banana-2-1 returns a task ID when the task is accepted:

integer

API status code. 200 means the task was accepted.

string

Human-readable status message.

string

Unique task identifier used with the status endpoint.

Status response fields

string

Unique task identifier.

string

Current task state: pending, processing, success, or failed.

string

JSON string containing a resultUrls array. Present when state is success.

string

Machine-readable failure code. Present when state is failed.

string

Human-readable failure message. Present when state is failed.

integer

Task creation timestamp in Unix milliseconds.

integer

Task completion timestamp in Unix milliseconds. Present after completion.

integer

Processing duration in milliseconds. Present after successful completion when available.

Webhook callback mode

Use callback mode when your backend should receive the final result automatically instead of polling.

curl -X POST "https://api.apixo.ai/api/v1/generateTask/nano-banana-2-1" \
  -H "Authorization: Bearer YOUR_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "request_type": "callback",
    "callback_url": "https://your-server.com/webhooks/apixo",
    "input": {
      "mode": "image-to-image",
      "prompt": "Turn this product photo into a polished studio ad",
      "image_urls": [
        "https://example.com/product.png"
      ],
      "aspect_ratio": "1:1",
      "resolution": "2K",
      "output_format": "png"
    }
  }'

See Webhooks for delivery requirements and retry behavior.

Billing

Nano Banana 2.1 is billed per generated image. The selected resolution determines the unit price.

Resolution	APIXO price
`1K`	`$0.04 / image`
`2K`	`$0.06 / image`
`4K`	`$0.135 / image`

For current published pricing, see Pricing.

Latency and polling

Actual latency varies by prompt complexity, reference image accessibility, resolution, and current queue load.

Stage	Guidance
First poll	Wait 10s-20s after task creation before the first status request
Poll interval	Poll every 10s while `state` is `pending` or `processing`
Production delivery	Use callback mode for high-concurrency workloads

Download and store important outputs promptly instead of relying on result URLs as permanent storage.

Rate limits and concurrency vary by account and API key. If you receive 429, slow down requests and retry with backoff.

Errors and troubleshooting

HTTP errors

Code	Meaning	What to do
`400`	Invalid request body, mode, parameter, or image URL shape	Fix the request before retrying
`401`	Missing or invalid API key	Check the `Authorization` header
`402`	Insufficient balance or quota	Add balance or switch account/key
`403`	Your key cannot access the model	Check account permissions
`429`	Rate limit or concurrency limit reached	Retry with exponential backoff
`500`	Server error	Retry with backoff
`502`	Generation service error	Retry with backoff
`504`	Generation timeout	Retry or use callback mode for long-running jobs

Task failure codes

Fail code	Meaning	What to do
`PromptInvalid`	Prompt was invalid or rejected	Revise the prompt
`SensitiveContent`	Prompt, reference, or output violated safety policy	Change the prompt or reference image
`ImageFormatIncorrect`	A reference image could not be processed	Use a public, directly fetchable image URL in a common image format
`MissingParameter`	A required parameter was missing	Check `mode`, `prompt`, and `image_urls` when editing
`RateLimited`	Generation capacity was temporarily limited	Retry with backoff
`Timeout`	Generation timed out	Retry or use callback mode
`Unknown error`	The failure did not match a known rule	Retry with backoff or contact support with the `taskId`

See Error Codes for the full error reference.

​Overview

​Endpoint and authentication

​Copy-paste async quickstart

​Poll for result

​Request body

​Text-to-image

​Image-to-image

​Parameters

​Response format

​Submit task response

​Status response fields

​Webhook callback mode

​Billing

​Latency and polling

​Errors and troubleshooting

​HTTP errors

​Task failure codes

​Related links

Overview

Endpoint and authentication

Copy-paste async quickstart

Poll for result

Request body

Text-to-image

Image-to-image

Parameters

Response format

Submit task response

Status response fields

Webhook callback mode

Billing

Latency and polling

Errors and troubleshooting

HTTP errors

Task failure codes

Related links