# FLUX.3 Klein API

> Text-to-image b’daqsijiet 4K nattivi, kontroll fakultattiv tat-tqassim permezz ta’ bounding box u sa 4 immaġnijiet għal kull talba

Jiġġenera immaġnijiet minn `prompt` testwali dettaljat. Kull naħa ta’ `image_size` tista’ tvarja minn 256 sa 4096 pixel, u tista’ titlob minn 1 sa 4 immaġnijiet għal kull sejħa. Sa 32 `bounding_boxes` jippermettulek tqiegħed oġġetti msemmija f’pożizzjonijiet stabbiliti fil-frame. L-output jista’ jkun png, jpeg jew webp, u l-espansjoni tal-prompt tista’ tinxtegħel jew tintefa.

- Model id: `blackforestlabs/flux-3/klein/text-to-image`
- Made by: Black Forest Labs
- Category: Text to Image
- Output: image
- Price per run: from $0.008 / run of output image (cheapest run $0.008 (8 API credits))
- Run: `POST https://api.doitong.ru/v1/run/blackforestlabs/flux-3/klein/text-to-image`
- Quote: `POST https://api.doitong.ru/v1/quote/blackforestlabs/flux-3/klein/text-to-image`
- Docs page: https://doitong.com/mt/developers/models/blackforestlabs/flux-3/klein/text-to-image

## Pricing

Price: **from $0.008 / run of output image** (the lowest tier; the quote prices your exact input). Price per run: the input files are measured before the run (length, resolution, frame rate). The quote measures the same files and is exactly what the run charges.

The full example input below costs $0.009 = 9 API credits (1 run × $0.009).

Prices are the upstream price in USD, paid from the API balance in API credits (1000 API credits = 1 USD). `POST https://api.doitong.ru/v1/quote/blackforestlabs/flux-3/klein/text-to-image` with the same JSON body returns the exact price for that input; the quote is exactly what a run charges. Invalid input is never charged and failed or canceled requests are refunded automatically.

## Input parameters

Send either the canonical name or the native field name (not both). Canonical names are the same across models.

| Parameter | Canonical name | Type | Required | Default | Allowed values / range | Description |
|---|---|---|---|---|---|---|
| `prompt` |  | string | yes |  |  | Istruzzjonijiet tal-ġenerazzjoni tal-immaġni li jiddeskrivu s-suġġett, l-inkwadrar, id-dawl u l-isfond fid-dettall, skont il-captions dettaljati użati biex jitħarreġ il-mudell. |
| `enable_prompt_expansion` |  | boolean | no | `true` |  | Estensjoni tal-prompt f’caption dettaljata qabel il-ġenerazzjoni, attivata meta tkun true. Għall-editjar, il-caption tkun ibbażata fuq l-immaġnijiet ta’ referenza. |
| `seed` |  | integer \| null | no |  |  | Żerriegħa għal immaġnijiet riproduċibbli: prompt u żerriegħa identiċi jipproduċu immaġni identika meta l-verżjoni tal-mudell ma tinbidilx. |
| `num_images` | `num_outputs` | integer | no | `1` | 1 – 4 | Għadd ta’ immaġnijiet mitlub għall-ġenerazzjoni. |
| `enable_safety_checker` |  | boolean | no | `true` |  | Attivazzjoni tal-kontroll tas-sikurezza; true jippermetti l-kontroll. |
| `output_format` |  | enum (string) | no | `png` | `jpeg`, `png`, `webp` | Format tal-fajl għall-immaġni li tirriżulta. |
| `image_size` |  | object {width, height} \| enum (string) | no | `square_hd` | `square_hd`, `square`, `portrait_4_3`, `portrait_16_9`, `landscape_4_3`, `landscape_16_9` | Issettja l-wisa’ u l-għoli tal-output b’mod indipendenti fi ħdan 256–4096 pixels, b’appoġġ għall-ġenerazzjoni nattiva 4K. |
| `bounding_boxes` |  | array of object {label, description, box} \| null | no |  | ≤ 32 items | Layout f’kaxxi mhux obbligatorju li jżomm kull oġġett deskritt fil-kaxxa assenjata lilu; identifika l-kaxxi permezz ta’ tikketti fil-prompt, eż. `A red fox <fox> sits under a red umbrella <umbrella>`. Il-koordinati jesprimu t-truf tal-kaxxa bħala frazzjonijiet tad-dimensjonijiet tal-immaġni, imkejla mill-oriġini ta’ fuq fuq ix-xellug (0, 0). |
| `bounding_boxes[].label` |  | string \| null | no |  | ≤ 64 characters | Tikketta qasira tal-oġġett għall-kaxxa, bħal `fox`; il-valur prestabbilit huwa `obj_<n>`. Inkludi `<fox>` fil-prompt biex tassoċja kliemu mal-kaxxa; kaxxi li ma jissemmewx fil-prompt jiżdiedu max-xena. |
| `bounding_boxes[].description` |  | string | yes |  | ≤ 500 characters | Oġġett li għandu jiġi rrendut fil-kaxxa, inkluż id-dehra tiegħu. |
| `bounding_boxes[].box` |  | object {x_min, y_min, x_max, y_max} | yes |  |  | Tqegħid tal-oġġett fl-immaġni output. |
| `bounding_boxes[].box.x_min` |  | number | yes |  | 0 – 1 | Limitu tax-xellug espress relattivament għall-wisa’ tal-immaġni, minn 0 sa 1. |
| `bounding_boxes[].box.y_min` |  | number | yes |  | 0 – 1 | Limitu ta’ fuq espress relattivament għall-għoli tal-immaġni, minn 0 sa 1. |
| `bounding_boxes[].box.x_max` |  | number | yes |  | 0 – 1 | Limitu tal-lemin espress relattivament għall-wisa’ tal-immaġni, minn 0 sa 1. |
| `bounding_boxes[].box.y_max` |  | number | yes |  | 0 – 1 | Limitu t’isfel espress relattivament għall-għoli tal-immaġni, minn 0 sa 1. |

## Example input

Required parameters only:

```json
{
  "prompt": "A red fox trots through fresh snow at sunrise, soft golden light, shallow depth of field"
}
```

A fuller example:

```json
{
  "prompt": "A red fox trots through fresh snow at sunrise, soft golden light, shallow depth of field"
}
```

## Run it

Set `DOITONG_API_KEY` to a key from https://doitong.com/developers/dashboard#keys. `?wait=20` returns the finished request in the same call when it is ready within 20 seconds; otherwise poll `GET /requests/{id}` (it also accepts `?wait=`), or pass `webhook_url`.

### curl

```bash
# Run the model; wait up to 20 s for the finished result in the same call
curl -X POST "https://api.doitong.ru/v1/run/blackforestlabs/flux-3/klein/text-to-image?wait=20" \
  -H "Authorization: Bearer $DOITONG_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "prompt": "A red fox trots through fresh snow at sunrise, soft golden light, shallow depth of field"
  }'

# Still "queued" or "running"? Poll with the id from the response:
curl "https://api.doitong.ru/v1/requests/REQUEST_ID?wait=20" \
  -H "Authorization: Bearer $DOITONG_API_KEY"
```

### JavaScript

```javascript
const API = "https://api.doitong.ru/v1";
const headers = {
  "Authorization": "Bearer " + process.env.DOITONG_API_KEY,
  "Content-Type": "application/json",
};

// Run the model; wait up to 20 s for the finished result in the same call
let res = await fetch(API + "/run/blackforestlabs/flux-3/klein/text-to-image?wait=20", {
  method: "POST",
  headers,
  body: JSON.stringify({
    "prompt": "A red fox trots through fresh snow at sunrise, soft golden light, shallow depth of field"
  }),
});
let request = await res.json();
if (!res.ok) throw new Error(request.error.code + ": " + request.error.message);

// Not finished yet: long-poll until it is
while (request.status === "queued" || request.status === "running") {
  res = await fetch(API + "/requests/" + request.id + "?wait=20", { headers });
  request = await res.json();
}
if (request.status !== "succeeded") throw new Error(JSON.stringify(request.error));
console.log(request.outputs.map((o) => o.url), request.cost.credits + " API credits ($" + request.cost.usd + ")");
```

### Python

```python
import os
import requests

API = "https://api.doitong.ru/v1"
headers = {"Authorization": "Bearer " + os.environ["DOITONG_API_KEY"]}

payload = {
    "prompt": "A red fox trots through fresh snow at sunrise, soft golden light, shallow depth of field",
}

# Run the model; wait up to 20 s for the finished result in the same call
r = requests.post(API + "/run/blackforestlabs/flux-3/klein/text-to-image", params={"wait": 20}, json=payload, headers=headers)
request = r.json()
if not r.ok:
    raise RuntimeError(request["error"]["code"] + ": " + request["error"]["message"])

# Not finished yet: long-poll until it is
while request["status"] in ("queued", "running"):
    request = requests.get(API + "/requests/" + request["id"], params={"wait": 20}, headers=headers).json()
if request["status"] != "succeeded":
    raise RuntimeError(request["error"])
print([o["url"] for o in request["outputs"]], request["cost"]["credits"], "API credits", "$" + request["cost"]["usd"])
```

### MCP

The MCP server at `https://api.doitong.ru/v1/mcp` exposes the tools `search_models`, `get_model`, `quote`, `run`, `get_request`, `cancel_request`, `list_requests`, `create_upload` and `get_account`. A `run` call for this model:

```json
{
  "jsonrpc": "2.0",
  "id": 1,
  "method": "tools/call",
  "params": {
    "name": "run",
    "arguments": {
      "model_id": "blackforestlabs/flux-3/klein/text-to-image",
      "input": {
        "prompt": "A red fox trots through fresh snow at sunrise, soft golden light, shallow depth of field"
      },
      "wait_seconds": 20
    }
  }
}
```

## Response

Every call returns a request object. `status` is one of `queued`, `running`, `succeeded`, `failed`, `canceled`. `outputs` lists the generated files with URLs on our storage (kept forever, or 7 days with `?storage=temporary`; `storage` says which); `output` is the model's own result object with the same URLs.

```json
{
  "id": "req_8k2m4q7x1z9c3v5b6n0p2r4t",
  "object": "request",
  "model": "blackforestlabs/flux-3/klein/text-to-image",
  "status": "succeeded",
  "created_at": "2026-10-20T12:00:00Z",
  "started_at": "2026-10-20T12:00:02Z",
  "completed_at": "2026-10-20T12:00:09Z",
  "queue_position": null,
  "cost": {
    "credits": 9,
    "usd": "0.009",
    "charged": 9,
    "refunded": 0
  },
  "input": {
    "prompt": "A red fox trots through fresh snow at sunrise, soft golden light, shallow depth of field"
  },
  "output": {
    "images": [
      {
        "url": "https://content.doitong.com/dev-api/2026/10/20/req_8k2m4q7x1z9c3v5b6n0p2r4t/0-output.jpeg",
        "content_type": "image/jpeg",
        "file_name": "0-output.jpeg",
        "file_size": 1843200,
        "width": 1024,
        "height": 768
      }
    ],
    "timings": {},
    "seed": 42,
    "has_nsfw_concepts": [
      false
    ],
    "prompt": "string"
  },
  "outputs": [
    {
      "type": "image",
      "url": "https://content.doitong.com/dev-api/2026/10/20/req_8k2m4q7x1z9c3v5b6n0p2r4t/0-output.jpeg",
      "content_type": "image/jpeg",
      "file_size": 1843200,
      "width": 1024,
      "height": 768,
      "stored": true
    }
  ],
  "error": null,
  "metrics": {
    "inference_seconds": 6.8
  },
  "urls": {
    "self": "https://api.doitong.ru/v1/requests/req_8k2m4q7x1z9c3v5b6n0p2r4t",
    "cancel": "https://api.doitong.ru/v1/requests/req_8k2m4q7x1z9c3v5b6n0p2r4t/cancel"
  }
}
```

### Output fields (`output`)

| Field | Type | Description |
|---|---|---|
| `images` | array of object {url, content_type, file_name, file_size, width, height} | Immaġnijiet prodotti mill-mudell. |
| `timings` | object | Informazzjoni dwar il-ħin tal-proċess tal-ġenerazzjoni. |
| `seed` | integer | Żerriegħa tal-ġenerazzjoni għall-ewwel immaġni. |
| `has_nsfw_concepts` | array of boolean | Jindika jekk kunċetti NSFW jidhrux fl-immaġnijiet ġġenerati. |
| `prompt` | string | Prompt użat waqt il-ġenerazzjoni tal-immaġni. |

## Related models

- [FLUX.3 Klein Image Editing](https://doitong.com/developers/models/blackforestlabs/flux-3/klein/edit-image.md) (`blackforestlabs/flux-3/klein/edit-image`): from $0.008 / run of output image
- [FLUX.1 \[dev\]](https://doitong.com/developers/models/flux/dev.md) (`flux/dev`): $0.025 / megapixel
- [FLUX.1 \[schnell\]](https://doitong.com/developers/models/flux/schnell.md) (`flux/schnell`): $0.003 / megapixel
- [FLUX.2 \[dev\]](https://doitong.com/developers/models/flux-2.md) (`flux-2`): $0.012 / megapixel
- [FLUX.2 \[pro\]](https://doitong.com/developers/models/flux-2-pro.md) (`flux-2-pro`): $0.015 / megapixel of output image
- [GPT Image 2.5 Text to Image](https://doitong.com/developers/models/openai/gpt-image-2.5/flare/text-to-image.md) (`openai/gpt-image-2.5/flare/text-to-image`): from $0.008 / image
- [Ideogram V4.5](https://doitong.com/developers/models/ideogram/v4.5.md) (`ideogram/v4.5`): from $0.03 / image
- [Nano Banana 2](https://doitong.com/developers/models/nano-banana-2.md) (`nano-banana-2`): from $0.06 / image

## Links

- HTML page: https://doitong.com/developers/models/blackforestlabs/flux-3/klein/text-to-image
- All models and guides for AI agents: https://doitong.com/developers/llms.txt
- OpenAPI 3.1 with this model's typed request body: https://doitong.com/developers/openapi.json?model=blackforestlabs/flux-3/klein/text-to-image
- Errors: https://doitong.com/developers/docs/errors
- Model details as JSON: https://api.doitong.ru/v1/models/blackforestlabs/flux-3/klein/text-to-image