bfl/flux-2/klein/9b/base
Flux 2 Klein 9b by BFL - generate stunning images from text prompts with state-of-the-art AI. Supports multiple aspect ratios, styles, and high-resolution output for creative and commercial use.
Example output — click Run to generate your own
Send your first request
OpenAI-compatible endpoint with unified authentication and usage tracking.
https://api.sandbase.ai/v1/runbfl/flux-2/klein/9b/baseInput 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, ortimeout - Retrieve — Read
outputsfrom 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/9b/base",
"prompt": "A cyberpunk samurai standing in neon-lit Tokyo street at night, rain-soaked pavement reflecting holographic advertisements in pink and blue, steam rising from street vents, wearing futuristic armor with glowing accents, cinematic composition, Unreal Engine 5 quality, ray-traced reflections, shallow depth of field, hyper-detailed",
"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"API README
Flux 2 Klein 9b
Flux 2 Klein 9b exposes the FLUX.2 Klein 9B Base capability for compact image generation. The undistilled Base architecture retains full training signal and higher output diversity for adaptation and research.
Use this 9B route when a stronger quality-to-speed balance and more complex visual understanding matter. Write a detailed narrative prompt because Klein does not depend on automatic prompt upsampling. Choose the Base form for fine-tuning or diverse research outputs rather than minimum inference latency.
Highlights
- FLUX.2 Klein 9B Base architecture. Uses the undistilled 9B foundation with full training signal and diverse output behavior.
- Detailed image generation. Creates coherent photographic and designed imagery from narrative prompts.
- Expanded visual capacity. Uses the larger Klein variant for more complex concepts and a stronger quality-speed balance.
- Fine-tuning foundation. Provides an adaptable starting point for LoRA training, full fine-tuning, and research.
Pricing
| Configuration | Billing unit | Price |
|---|---|---|
| Base generation | Per request | $0.015 |
When to Use
| ✅ Good fit | ❌ Consider alternatives |
|---|---|
| The project needs this exact generation or editing route | The intended task belongs to video, audio, or 3D media |
| Available references match every required local field | Required source assets or rights are unavailable |
| The brief can specify composition, color, and finish | Output must be deterministic at pixel level |
| Supported dimensions and formats fit final placement | Delivery requires unsupported canvas specifications |
| An asynchronous generated image fits production | A live frame-synchronous response is mandatory |
Prompt Guide
Write a complete visual brief: identify the subject and references, define composition and viewpoint, describe lighting, palette, materials, typography, and finish, then list exact preservation constraints. FLUX.2 Klein does not rely on prompt upsampling, so use clear descriptive sentences rather than sparse keywords.
{
"prompt": "A photorealistic editorial composition with precise subject placement, controlled lighting, exact colors, and clean typography",
"seed": 1,
"aspect_ratio": "21:9",
"output_format": "jpeg"
}
Technical Specs
| Spec | Value |
|---|---|
| Model ID | bfl/flux-2/klein/9b/base |
| Input fields | seed (integer)<br>prompt (string)<br>aspect_ratio (string; 21:9, 16:9, 3:2, 4:3, 5:4, 1:1, 4:5, 3:4, 2:3, 9:16)<br>output_format (string; jpeg, png)<br>guidance_scale (number; 0–20)<br>num_inference_steps (integer; 4–50) |
| Required input | prompt |
| Output fields | url, content_type |
| Execution | Asynchronous job |
Related Models
bfl/flux-2/klein/4bbfl/flux-2/klein/4b/basebfl/flux-2/klein/4b/base/edit