FLUX.2 [klein] 4B Base LoRA

POST/v1/run

Flux 2 Klein 4b by BFL - AI-powered image editing, style transfer, and transformation. Edit photos with natural language instructions, remove backgrounds, change styles, and enhance images effortlessly.

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/base/edit/lora.

Default: bfl/flux-2/klein/4b/base/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<number>guidance_scale

Guidance scale for classifier-free guidance.

Range: 0 to 20

Default: 5

Optional<integer>num_inference_steps

The number of inference steps to perform.

Range: 4 to 50

Default: 28

Optional<string>output_format

The format of the generated image.

Allowed values: jpeg, png

Default: png

Optional<array<object>>loras

List of LoRA weights to apply (maximum 3).

Default:

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.

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/base/edit/lora",
  "prompt": "Change his clothes to casual suit and tie",
  "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/base/edit/lora",
  "status": "running",
  "outputs": []
}