Images API v1

The images API endpoint allows you to generate AI images using various models from different providers like OpenAI, Together AI, Google, and OpenRouter. Generate stunning visuals from text prompts with a unified API interface.

Generate a User/Org API key

You will need to generate an API key to authenticate your requests. For more information, visit the User/Org API key documentation.

LLM API Keys Required

You'll need to add the LLM API keys for the image generation providers you want to use. The API key should be passed in the LB-LLM-Key header.

POST/v1/images

Generate images

Generate AI images by sending a text prompt to the images API endpoint.

Headers

Name
Content-Type
Type
string
Required
Required
Description
Request content type. Needs to be application/json.
Name
Authorization
Type
string
Required
Required
Description
Replace <YOUR_API_KEY> with your user/org API key.
Name
LB-LLM-Key
Type
string
Required
Required
Description
Your LLM provider API key (OpenAI, Together AI, Google, etc.).

Request Body

Name
prompt
Type
string
Required
Required
Description
A text description of the image you want to generate. Be descriptive for best results.
Name
model
Type
string
Required
Required
Description
The image generation model to use. Format: provider:model-name
Examples:
- openai:gpt-image-1
- together:black-forest-labs/FLUX.1-schnell-Free
- google:gemini-2.5-flash-image-preview
- openrouter:google/gemini-2.5-flash-image-preview
Name
width
Type
number
Description
The width of the generated image in pixels. Default varies by model.
Common values: 1024, 1792, 512
Name
height
Type
number
Description
The height of the generated image in pixels. Default varies by model.
Common values: 1024, 1792, 512
Name
n
Type
number
Description
The number of images to generate.
Default: 1
Name
steps
Type
number
Description
Number of inference steps (for models that support it).
Higher values may produce better quality but take longer.
Name
image_url
Type
string
Description
Base image URL for image-to-image generation (if supported by the model).

Usage example

Install the SDK

npm i langbase

Environment variables

.env file

LANGBASE_API_KEY="<YOUR_API_KEY>"
OPENAI_API_KEY="<YOUR_OPENAI_KEY>"

Generate an image

Generate Image

POST

/v1/images

curl https://api.langbase.com/v1/images \
-X POST \
-H 'Authorization: Bearer <YOUR_API_KEY>' \
-H 'LB-LLM-Key: <YOUR_OPENAI_KEY>' \
-H 'Content-Type: application/json' \
-d '{
  "prompt": "A futuristic cityscape with flying cars and neon lights",
  "model": "openai:gpt-image-1",
  "size": "1024x1024"
}'

Response

Response of the endpoint is a ImageGenerationResponse object.

ImageGenerationResponse Object

interface ImageGenerationResponse {
  id: string;
  provider: string;
  model: string;
  object: string;
  created: number;
  choices: Choice[];
  usage: Usage;
}

Name
id
Type
string
Description
Unique identifier for the image generation request.
Name
provider
Type
string
Description
The provider used for image generation (e.g., "openai", "together", "google").
Name
model
Type
string
Description
The model used for image generation.
Name
object
Type
string
Description
Object type, typically "chat.completion".
Name
created
Type
number
Description
Unix timestamp of when the image was created.
Name
choices
Type
Choice[]
Description
Array of generated image results. Can contain more than one element if n is greater than 1.
Choice Object
interface Choice { logprobs: null; finish_reason: string; native_finish_reason: string; index: number; message: Message; }
Name
usage
Type
Usage
Description
Token usage statistics for the request.
Usage Object
interface Usage { prompt_tokens: number; completion_tokens: number; total_tokens: number; prompt_tokens_details: PromptTokensDetails; completion_tokens_details: CompletionTokensDetails; }

API Response

{
  "id": "chatcmpl-xxx",
  "provider": "openai",
  "model": "gpt-image-1",
  "object": "chat.completion",
  "created": 1234567890,
  "choices": [
    {
      "logprobs": null,
      "finish_reason": "stop",
      "native_finish_reason": "stop",
      "index": 0,
      "message": {
        "role": "assistant",
        "content": null,
        "images": [
          {
            "type": "image_url",
            "image_url": {
              "url": "https://oaidalleapiprodscus.blob.core.windows.net/..."
            },
            "index": 0
          }
        ]
      }
    }
  ],
  "usage": {
    "prompt_tokens": 15,
    "completion_tokens": 0,
    "total_tokens": 15,
    "prompt_tokens_details": {
      "cached_tokens": 0
    },
    "completion_tokens_details": {
      "reasoning_tokens": 0,
      "image_tokens": 1
    }
  }
}

API Reference