FLUX.2 [klein] 4B LoRA

POST/v1/run

Flux 2 Klein 4b is BFL's intelligent image editing model. Transform, retouch, and reimagine existing images using text prompts - from background replacement to artistic style conversion.

Request body

Submit an async generation request. The model field selects the model; other fields are model-specific input parameters.

stringmodelrequired

Model identifier. Set to bfl/flux-2/klein/4b/edit/lora.

Default: bfl/flux-2/klein/4b/edit/lora

stringpromptrequired

The prompt to edit the image.

Optional<array<string>>images

The URLs of the images for editing. A maximum of 4 images are allowed.

Optional<string>output_format

The format of the generated image.

Allowed values: jpeg, png

Default: png

Optional<string>aspect_ratio

The aspect ratio of the generated image.

Allowed values: 21:9, 16:9, 3:2, 4:3, 5:4, 1:1, 4:5, 3:4, 2:3, 9:16

Optional<integer>seed

The seed to use for the generation. If not provided, a random seed will be used.

Optional<integer>num_inference_steps

Number of denoising or inference steps to run when supported.

Range: 4 to 8

Default: 4

Optional<array>loras

Request parameter supported by this model.

Default:

Response Schema

The submit endpoint returns an accepted generation task. Poll the result endpoint with the returned id for terminal outputs or errors.

Optional<string>error

Error message if the task failed. Empty on success.

stringidrequired

Unique identifier for the generation task.

Optional<string>model

Model ID used for the prediction.

Optional<array>outputs

Array of generated content. Empty when status is not completed.

stringstatusrequired

Status of the task: pending, running, completed, failed, or timeout.

Allowed values: pending, running, completed, failed, timeout

Model capabilities

array<string>capability_tagsrequired

Capabilities declared by the model registry.

Default: image-to-image

stringexecution_moderequired

Execution mode declared by the model registry.

Default: async

# 1. Submit a generation request
curl -X POST https://api.sandbase.ai/v1/run \
  -H "Authorization: Bearer $SANDBASE_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
  "model": "bfl/flux-2/klein/4b/edit/lora",
  "prompt": "Turn this into a realistic image",
  "output_format": "png",
  "aspect_ratio": "21:9"
}'

# 2. If the response is still running, poll the returned id
curl https://api.sandbase.ai/v1/run/run_abc123 \
  -H "Authorization: Bearer $SANDBASE_API_KEY"

Response202 Accepted

{
  "id": "run_abc123",
  "model": "bfl/flux-2/klein/4b/edit/lora",
  "status": "running",
  "outputs": []
}