Klein API Reference

Overview

The Klein API provides a synchronous interface for generating high-quality images from text prompts and reference images. All generation workflows are accessed through a single endpoint. The API automatically selects the appropriate workflow based on the number of reference images provided:

• 0 images → Text-to-image generation
• 1 image → Image-to-image editing
• 2–4 images → Multi-reference generation

Authentication

All requests to the API must include a Bearer token in the Authorization header.

Example header:
Authorization: Bearer YOUR_API_KEY

Endpoint

POST /v1/generate

Generates or edits an image based on a text prompt and optional reference images. Uses multipart/form-data content type.

Workflow Selection

The workflow is automatically determined by the total number of reference images (from images and image_uris combined):

cURL Examples

Text-to-image (no images):

curl -X POST https://us-01.bytecompute.ai/v1/generate \
  -H "Authorization: Bearer " \
  -F "prompt=A futuristic city with neon lights" \
  -F "model=flux2-klein-4b" \
  -F "aspect_ratio=square"

Image-to-image (1 image):

curl -X POST https://us-01.bytecompute.ai/v1/generate \
  -H "Authorization: Bearer " \
  -F "prompt=A cat wearing a space suit" \
  -F "model=flux2-klein-4b" \
  -F "images=@/path/to/your/image.png" \
  -F "aspect_ratio=portrait"

Multi-reference (2+ images):

curl -X POST https://us-01.bytecompute.ai/v1/generate \
  -H "Authorization: Bearer " \
  -F "prompt=A hybrid of these two animals" \
  -F "model=flux2-klein-4b" \
  -F "images=@/path/to/image1.png" \
  -F "images=@/path/to/image2.png" \
  -F "aspect_ratio=landscape"

Response

The response body contains the raw PNG bytes of the generated image with a Content-Type of image/png.

Response headers:

• X-Generation-Id: Unique identifier for the generation.
• X-Generation-Time: Time taken to generate the image in seconds.
• X-Resolution: Resolution of the generated image.
• X-Model: Model identifier used.
• X-Workflow: Workflow that was selected (t2i, i2i, or multi-ref).
• X-Reference-Count: The number of reference images used (only present when images are provided).

Error Responses

The API uses standard HTTP status codes to indicate the success or failure of a request. Errors are returned in a unified JSON format.

{
  "detail": "Error message description"
}

Status codes:

• 401 Unauthorized: Authentication failed due to a missing or invalid API key.
• 422 Unprocessable Entity: The request parameters failed validation.
• 504 Gateway Timeout: The generation process exceeded the allowed time limit.
• 500 Internal Server Error: An unexpected error occurred on the server.

Limits

Available aspect ratios and their corresponding resolutions: