> ## Documentation Index
> Fetch the complete documentation index at: https://docs.bettertoken.ai/llms.txt
> Use this file to discover all available pages before exploring further.
# Gemini text-to-image API
> Generate images with Nano Banana through BetterToken’s Gemini API. Try model selection, prompts, resolutions and aspect ratios in the interactive API playground.
Generate an image from a text description with Nano Banana Pro, 2, or 2.1.
`POST /v1beta/models/{model}:generateContent`
Text-to-image and image editing use the same endpoint. Image editing adds a reference image to the request.
## Try a request
Enter your BetterToken API Key in **x-goog-api-key**, select **model**, and edit the text in **contents**. Start with `1K` and `1:1`, then click **Send**.
Clicking **Send** makes a real generation request and may incur charges. Wait for the synchronous response. After a timeout or disconnection, check usage records and the request result before sending it again.
All three offer `1K`, `2K`, and `4K`. Nano Banana 2 and 2.1 support 14 aspect ratios; Pro supports 10. `X-BetterToken-Max-Images` is a delivery and billing cap, not a guaranteed image count. [Aspect ratios](/en/api-reference/nano-banana#aspect-ratios)
BetterToken API does not support search-assisted image generation, including Google Web Search and Image Search grounding. Do not add search tools.
Text-to-image requires only a text description; no reference image is needed. Use non-streaming `generateContent`. Files, Batch, Interactions, and streaming are not supported.
## Read the response
Images are returned in `candidates[].content.parts[].inlineData`. Iterate over the parts, skip `thought: true`, decode `data`, and choose the file extension from `mimeType`. Do not assume the image is always the first part or always PNG.
## Related guides
* [Image editing](/en/api-reference/gemini-images-edits)
* [SDK, image saving, and multi-turn editing](/en/api-reference/nano-banana)
* [Model introduction](/en/model-updates/nano-banana)
* Model plaza
## OpenAPI
````yaml api-reference/gemini-images-generations.en.json POST /v1beta/models/{model}:generateContent
openapi: 3.1.0
info:
title: Gemini text-to-image API
description: >-
Generate images with Nano Banana through BetterToken’s Gemini API. Try model
selection, prompts, resolutions and aspect ratios in the interactive API
playground.
version: 1.0.0
servers:
- url: https://bettertoken.ai
security:
- geminiApiKey: []
paths:
/v1beta/models/{model}:generateContent:
post:
summary: Gemini text-to-image API
description: >-
Generate an image from a text description with Nano Banana Pro, 2, or
2.1. BetterToken API does not support search-assisted image generation,
including Google Web Search and Image Search grounding. Do not add
search tools.
operationId: generateGeminiImage_en
parameters:
- name: model
in: path
required: true
description: BetterToken Model ID. Choose one of the three Nano Banana models.
schema:
type: string
enum:
- nano-banana-pro
- nano-banana-2
- nano-banana-2.1
default: nano-banana-2.1
- name: X-BetterToken-Max-Images
in: header
description: >-
Maximum number of returned and billable images, not a guaranteed
count. Defaults to 1.
schema:
type: integer
minimum: 1
maximum: 4
default: 1
requestBody:
required: true
content:
application/json:
schema:
type: object
required:
- contents
properties:
contents:
type: array
description: >-
Conversation contents. Keep the complete model content and
thoughtSignature for follow-up edits.
minItems: 1
items:
type: object
required:
- parts
properties:
role:
type: string
description: >-
Use user for a new request; use model for previous
model responses in editing history.
enum:
- user
- model
default: user
parts:
type: array
description: >-
Text and image parts. Put text and inlineData in
separate parts.
minItems: 1
items:
anyOf:
- type: object
required:
- text
properties:
text:
type: string
description: Image description or editing instruction.
example: >-
A studio product photograph of a blue
ceramic mug on a white table.
additionalProperties: true
- type: object
required:
- inlineData
properties:
inlineData:
type: object
description: Reference image embedded as base64.
required:
- mimeType
- data
properties:
mimeType:
type: string
description: The reference image MIME type.
enum:
- image/png
- image/jpeg
example: image/png
data:
type: string
description: >-
Raw base64 image bytes, without a Data
URL prefix.
contentEncoding: base64
example: REPLACE_WITH_IMAGE_BASE64
additionalProperties: false
additionalProperties: true
additionalProperties: false
generationConfig:
type: object
description: Image generation settings.
properties:
responseModalities:
type: array
description: Explicitly request image output.
items:
type: string
enum:
- IMAGE
default:
- IMAGE
candidateCount:
type: integer
enum:
- 1
default: 1
description: Omit or use the integer 1. Do not send root-level n.
imageConfig:
type: object
description: Output image settings.
properties:
imageSize:
type: string
description: Output resolution. Use uppercase K.
enum:
- 1K
- 2K
- 4K
default: 1K
aspectRatio:
type: string
description: >-
Aspect ratio. Pro supports 10 ratios; 2 and 2.1 also
support 1:4, 4:1, 1:8, and 8:1.
enum:
- '1:1'
- '1:4'
- '1:8'
- '2:3'
- '3:2'
- '3:4'
- '4:1'
- '4:3'
- '4:5'
- '5:4'
- '8:1'
- '9:16'
- '16:9'
- '21:9'
default: '1:1'
additionalProperties: false
additionalProperties: false
additionalProperties: false
example:
contents:
- role: user
parts:
- text: >-
A studio product photograph of a blue ceramic mug on a
white table.
generationConfig:
responseModalities:
- IMAGE
candidateCount: 1
imageConfig:
imageSize: 1K
aspectRatio: '1:1'
responses:
'200':
description: Generation response. Inspect final image parts and finishReason.
content:
application/json:
schema:
type: object
properties:
candidates:
type: array
items:
type: object
properties:
content:
type: object
properties:
role:
type: string
parts:
type: array
items:
type: object
properties:
text:
type: string
thought:
type: boolean
thoughtSignature:
type: string
inlineData:
type: object
properties:
mimeType:
type: string
data:
type: string
contentEncoding: base64
finishReason:
type: string
promptFeedback:
type: object
additionalProperties: true
usageMetadata:
type: object
additionalProperties: true
example:
candidates:
- content:
role: model
parts:
- inlineData:
mimeType: image/png
data: BASE64_IMAGE_DATA
finishReason: STOP
'400':
description: Invalid parameters or unsupported capability.
'401':
description: Missing or invalid API Key.
'402':
description: Insufficient balance.
'429':
description: Rate limit or upstream busy.
'500':
description: Generation service error. Check the request result before retrying.
components:
securitySchemes:
geminiApiKey:
type: apiKey
in: header
name: x-goog-api-key
description: BetterToken API Key.
````
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