Documentation Index
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Black Forest Labs’ 5.6B open-weight FLUX 3 image model: text-to-image, editing and multi-reference generation. See parameters, pricing, response fields, and API examples.
black-forest-labs/flux-3-image-klein
| Parameter | Type | Required | Default | Description |
|---|---|---|---|---|
prompt | string | Yes | - | Text description of the image, or the edit to apply to the reference images |
aspect_ratio | string | No | "16:9" | "21:9", "16:9", "4:3", "1:1", "3:4", "9:16", "9:21" |
resolution | string | No | "1mp" | "0.6mp", "1mp", "2mp", "4mp" |
image_urls | string[] | No | null | Up to 4 reference image URLs for editing or multi-reference generation |
steps | integer | No | 16 | Sampling steps, 1-50 |
seed | integer | No | random | Seed for reproducibility |
nsfw_check | boolean | No | true | Check uploaded media inputs for NSFW content |
guidance, negative_prompt or prompt_upsampling. For CFG guidance and a negative prompt use FLUX 3 Image Klein Base.curl -X POST https://api.unifically.com/v1/tasks -H "Content-Type: application/json" -H "Authorization: Bearer YOUR_API_KEY" -d '{
"model": "black-forest-labs/flux-3-image-klein",
"input": {
"prompt": "A minimalist line drawing of a mountain landscape",
"aspect_ratio": "16:9",
"resolution": "1mp",
"seed": 42
}
}'
curl -X POST https://api.unifically.com/v1/tasks -H "Content-Type: application/json" -H "Authorization: Bearer YOUR_API_KEY" -d '{
"model": "black-forest-labs/flux-3-image-klein",
"input": {
"prompt": "Keep the composition, change the season to deep winter with snow on every surface",
"image_urls": ["https://example.com/reference.png"]
}
}'
{
"code": 200,
"success": true,
"data": {
"task_id": "abc123def456",
"status": "processing"
}
}