API reference · BFL

bfl/flux-2/klein/4b/base

Integrate this model through SandBase's unified API, with production-ready schemas and examples.

IMAGEAsyncOpen model

Production endpoint

Send your first request

OpenAI-compatible endpoint with unified authentication and usage tracking.

POSThttps://api.sandbase.ai/v1/run

Model IDbfl/flux-2/klein/4b/base

Input Schema

6 parameters · 1 required · 5 optional

Parameter	Type	Required	Description
`prompt`	string	Required	The prompt to generate an image from.
`seed`	integer	Optional	The seed to use for the generation. If not provided, a random seed will be used.
`aspect_ratio`	string	Optional	The aspect ratio of the generated image. · Options: 21:9, 16:9, 3:2, 4:3, 5:4, 1:1, 4:5, 3:4, 2:3, 9:16 · Default: "16:9" 21:916:93:24:35:41:14:53:42:39:16
`output_format`	string	Optional	The format of the generated image. · Options: jpeg, png · Default: "png" jpegpng
`guidance_scale`	number	Optional	Guidance scale for classifier-free guidance. · Min: 0 · Max: 20 · Default: 5
`num_inference_steps`	integer	Optional	The number of inference steps to perform. · Min: 4 · Max: 50 · Default: 28

Output Schema

Field	Type	Description
`id`	string	Unique identifier for the generation task
`status`	string	Task status: pending, running, completed, failed, timeout
`model`	string	Model used for the generation
`outputs`	array	Array of output items
`outputs[].url`	string	URL of the generated artifact
`outputs[].content_type`	string	MIME type (e.g. image/png, video/mp4)
`error`	object \| null	Error details if failed, null on success
`error.type`	string	Machine-readable error type code
`error.message`	string	Human-readable error description

Async Workflow

This model uses asynchronous execution. Submit a request and poll for the result.

Submit — POST to /v1/run, receive an id
Poll — GET /v1/run/{id} until status is completed, failed, or timeout
Retrieve — Read outputs from the completed response

Code Examples

Ready-to-run snippets

# Step 1: Submit
curl -X POST https://api.sandbase.ai/v1/run \
  -H "Content-Type: application/json" \
  -H "Authorization: Bearer YOUR_API_KEY" \
  -d '{
  "model": "bfl/flux-2/klein/4b/base",
  "prompt": "Japanese zen garden at first light, perfect rake lines in gravel, koi pond with morning mist, temple bell in background, meditation ready",
  "aspect_ratio": "16:9",
  "output_format": "png",
  "guidance_scale": 5,
  "num_inference_steps": 28
}'

# Step 2: Poll result (replace <id>)
curl https://api.sandbase.ai/v1/run/<id> \
  -H "Authorization: Bearer YOUR_API_KEY"

← Back to Flux 2 Klein 4b