FLUX 3 Image - Unifically

Generate and edit images with FLUX 3 Image, the full FLUX 3 image model from Black Forest Labs. One route covers text-to-image, image editing and multi-reference generation with up to 10 reference images, and the prompt can carry bounding boxes that place each element. Try it in the browser: FLUX 3 Image API playground.

Model

black-forest-labs/flux-3-image

Parameters

Parameter	Type	Required	Default	Description
`prompt`	string	Yes	-	Text description of the image or the edit to apply. May end with a bounding-box element table (see below)
`image_urls`	string[]	No	`[]`	0-10 reference image URLs for editing or multi-reference generation. Refer to them in the prompt as image 1, image 2, …
`aspect_ratio`	string	No	`"auto"`	`"auto"`, `"21:9"`, `"2:1"`, `"16:9"`, `"3:2"`, `"7:5"`, `"4:3"`, `"5:4"`, `"1:1"`, `"4:5"`, `"3:4"`, `"5:7"`, `"2:3"`, `"9:16"`, `"1:2"`, `"9:21"`. With `auto` the prompt decides, or the first reference image’s framing when one is attached
`resolution`	string	No	`"1k"`	`"768sq"`, `"1k"`, `"1.5k"`, `"2k"`, `"4k"` (case-insensitive). Each is a fixed pixel area; exact dimensions follow the aspect ratio
`grounding`	boolean	No	`true`	Research the prompt with web and image search before generating. Set `false` for faster runs that use only the prompt

FLUX 3 Image has no seed, steps, guidance or negative_prompt. Output is a single JPG image.

Bounding boxes

Append a JSON array to the prompt, one row per element, and tag each element in the caption with its id (<cabin_1>). Each bbox is [top, left, bottom, right] on a 0 to 1000 grid at any aspect ratio.

A small black timber cabin <cabin_1> on a snowy slope, with the headline <headline_1> in the sky above it. [{"id": "headline_1", "bbox": [60, 60, 230, 640], "desc": "\"QUIET PLACES\" in a tall black serif typeface"}, {"id": "cabin_1", "bbox": [420, 250, 800, 620], "desc": "a small black timber cabin with a glowing window"}]

Example Request

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",
    "input": {
      "prompt": "A screen-printed concert poster with the headline \"BLUE HOUR SESSIONS\" above an upright bass player on cobalt blue",
      "aspect_ratio": "2:3",
      "resolution": "1k",
      "grounding": false
    }
  }'

Multi-reference generation:

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",
    "input": {
      "prompt": "The woman from image 1 inspects the watch movement from image 2 at a watchmaker bench",
      "image_urls": ["https://example.com/portrait.jpg", "https://example.com/movement.jpg"],
      "resolution": "2k"
    }
  }'

Response

{
  "code": 200,
  "success": true,
  "data": {
    "task_id": "abc123def456",
    "status": "processing"
  }
}

Poll GET /v1/tasks/<task_id> or set a callback_url to receive the finished image URL.

Volume discounts are available for almost all models. Reach out at contact@unifically.com to discuss custom pricing.

​Model

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​Bounding boxes

​Example Request

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Model

Parameters

Bounding boxes

Example Request

Response