# FLUX.3 Klein API

> ᡥᡡᠯᡥᠠᠨ ᡳ ᡳᠯᡥᠠᠴᡳᠨ 4K ᠵᠠᠯᡠᠨ᠂ ᠵᡠᠯᡝ ᡠᠯᡥᠠᠨ ᡳ ᠵᠠᠰᡳᡴᠠᠨ ᠪᡝ ᡠᠯᡥᠠᠨ᠂ ᡝᠮᡠ ᡩᡝ 4 ᡳᠯᡥᠠᠴᡳᠨ ᡩᡝ ᠵᠠᠯᡠᠨ

ᡝᠮᡤᡳ ᡥᡡᠯᠠᠨ ᡳ ᡶᠠᡵᠠᡥᠠ ᠪᡝ `prompt` ᡳ ᡩᡝᠯᡤᡳ ᡩᡝ ᡤᠠᠳᠠᠨ ᡥᠠᠰᡳᠯᠠᠮᠪᡳ᠉ `image_size` ᡳ ᠮᡠᠶᠠᡥᠠ ᠵᡠᠰᡝ 256 ᡩᡝᠴᡳ 4096 ᠫᡳᡴᠰᡝᠯ ᡩᡝ ᡤᠠᠮᠠᡵᠠ ᠪᡳᠮᠪᡳ᠉ ᡝᠮᡤᡳ ᡝᠮᡤᡳ ᠠᠯᡳᠨ ᡩᡝ 1 ᡩᡝᠴᡳ 4 ᡤᠠᠳᠠᠨ ᡩᠣᠰᡳᠮᠪᡳ᠉ 32 ᡥᡝᠰᡝ ᡩᡝᠴᡳ ᡠᠮᡝ ᠪᡳᠰᡳᡵᡝ `bounding_boxes` ᡝᡵᡝᠮᡝ ᠪᡠᠮᡝ ᡩᠣᠩᡤᠣᠨ ᡩᡠᠯᡳᠨ ᡳᠯᡳᡥᠠᠨ ᠰᡝᠪᡝ ᡶᡳᠯᡝᠮᡝ ᡳ ᡩᡝ ᡩᠠᡵᠠᠨ ᡩᡝ ᠵᠠᠯᠠᠨ ᠰᡳᠯᠠᠮᠪᡳ᠉ ᠪᡠᠶᡝᠮᡝ png, jpeg ᠠᠯᡳ webp ᠪᡳᠮᠪᡳ᠉ ᡥᡡᠯᠠᠨ ᡳ ᡤᠠᠮᠠᠮᠪᡳ ᡳᠯᡳ ᠠᠮᠠᠯᠠ ᠪᡝ ᡳᠯᡳ ᠠᠮᠠᠯᠠᠮᠪᡳ᠉

- 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/mnc/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 |  |  | ᡤᠠᠳᠠᠨ ᡳ ᠪᡠᠶᡝᠮᡝ ᡳ ᡥᡡᠯᠠᠨ, ᠵᠠᠩ, ᠨᡳᠶᠠᠯᠮᠠ, ᡳᠯᡤᠠᠨ ᠪᡝ ᡩᡝᠯᡝᠨ ᡥᡡᠯᠠᠮᡝ. |
| `enable_prompt_expansion` |  | boolean | no | `true` |  | ᡝᡵᡝᠮᡝ ᠪᡠᠮᡝ ᡩᡝ ᠵᡠᠯᡝ ᡳ ᡝᠮᡠᠯᡝᠨ ᡩᡝ ᡩᡝᠯᡝᠨ ᡥᡡᠯᠠᠨ ᠪᡠᠶᡝᠮᡝ ᠵᡠᠯᡝᠮᡝ ᠪᡠᠮᡝ. ᡥᡡᠯᠠᠨᡳ ᠵᡠᠯᡤᠠᠨ ᡤᠠᠳᠠᠨᡳ ᡝᡵᡝ ᠵᡠᠯᡝᠮᡝ ᠪᡠᠮᡝ. |
| `seed` |  | integer \| null | no |  |  | ᡳᠨᠠᠩᡤᠠ ᡤᠠᠳᠠᠨ ᡳ ᡶᡳᠶᠠᠩᡤᠠ ᠪᡠᠶᡝᠮᡝ ᡳ ᡝᠮᡠ ᡝᠨᡝᠩᡤᡳ ᡥᡡᠯᠠᠨ ᡳ ᠰᡝᠮᡝ ᡳᠨᡠ ᡝᠮᡠ ᡤᠠᠳᠠᠨ ᠪᡠᠶᡝᠮᡝ, ᠮᠣᠳᡝᠯᡳ ᡥᡡᠯᠠᠨ ᡳ ᡝᠮᡠ ᠵᠠᠩ ᠪᠠᠶᠠᠨ ᠪᡠᠮᡝ. |
| `num_images` | `num_outputs` | integer | no | `1` | 1 – 4 | ᠪᡠᠶᡝᠮᡝ ᡩᡝ ᠵᡠᠴᡝᠨ ᡳ ᠵᡠᠰᡝ ᡳ ᡩᡠᠯᠠᠨ᠉ |
| `enable_safety_checker` |  | boolean | no | `true` |  | ᠠᠮᡤᠠᠨᡳ ᠵᠠᠯᡳᠨ: true ᠪᡝ ᠵᠠᠯᡳᠨ ᠣᠮᠪᡳ᠉ |
| `output_format` |  | enum (string) | no | `png` | `jpeg`, `png`, `webp` | ᠪᡠᠶᡝᠮᡝ ᠵᡠᠴᡝᠨ ᡳ ᡶᡳᠯᡝ ᡳ ᠵᡠᠰᡝ᠉ |
| `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` | ᠪᡠᠶᡝᠮᡝ ᡳ ᡩᠠᠮᠪᠠᠨ ᠠᠴᠠ 256 ᡩᡝ 4096 ᡩᡝ ᡝᠮᡠᠯᡝᠨ ᡩᡝ ᠵᠠᠯᠠᠨ, ᠵᠠᠯᠠᠨ ᡳ ᡝᠮᡠᠯᡝᠨ ᡩᡝ ᠪᡠᠮᡝ; ᠵᡠᠯᡝ 4K ᠪᡠᠶᡝᠮᡝ ᠪᡝ ᠵᠠᠯᠠᠨ. |
| `bounding_boxes` |  | array of object {label, description, box} \| null | no |  | ≤ 32 items | ᠪᠠᡳᡥᠠᠴᡳ ᡥᡝᡵᡤᡝᠪᡠᡵᡝ ᡥᠠᡴᠰᠠᠨ ᡳ ᠪᠠᡳᠴᡳᠪᡠᠨ᠈ ᡤᡳᠰᡠᡵᡝᡥᡝ ᠵᠠᡴᠠ ᡨᠣᠮᡝ ᡨᡠᡥᡝᠪᡠᡥᡝ ᡥᠠᡴᠰᠠᠨ ᡳ ᠳᠣᠯᠣ ᡴᠣᡵᠣᠪᡠᠮᠪᡳ᠉ ᡥᡡᠯᠠᠨ ᡳ ᡤᡝᠪᡠ ᠪᡝ ᠪᠠᡳᡨᠠᠯᠠᠮᡝ ᡥᠠᡴᠰᠠᠨ ᠪᡝ ᡳᠯᡤᠠ᠈ ᠵᡝᡵᡤᡝ᠈ `A red fox <fox> sits under a red umbrella <umbrella>`᠉ ᠪᠠ ᡳ ᡨᠣᠨ ᡳ ᡥᠠᡴᠰᠠᠨ ᡳ ᠵᡝᠴᡝ ᠪᡝ ᡤᠠᠳᠠᠨ ᡳ ᡤᡠᠯᡝᠨ ᠵᠠᠩᡤᡳᠨ ᡳ ᡠᠪᡠ ᠣᠪᡠᠮᡝ ᡨᡠᠴᡳᠪᡠᠮᠪᡳ᠈ ᠳᡝᡵᡤᡳ ᡥᠠᠰᡥᡡ ᡝᡵᡤᡳ ᡳ ᡩᡝᡵᡳᠪᡠᠨ (0, 0) ᠴᡳ ᡥᡝᠮᠵᡝᠮᠪᡳ᠉ |
| `bounding_boxes[].label` |  | string \| null | no |  | ≤ 64 characters | ᡥᠠᡴᠰᠠᠨ ᡳ ᠵᠠᡴᠠ ᡳ ᡶᠣᡥᠣᠯᠣᠨ ᡤᡝᠪᡠ᠈ ᠵᡝᡵᡤᡝ `fox`᠉ ᠵᡠᠯᡝ ᠣᠴᡳ `obj_<n>`᠉ ᡤᡳᠰᡠᠨ ᠪᡝ ᡥᠠᡴᠰᠠᠨ ᡩᡝ ᡥᠣᠯᠪᠣᠮᡝ ᡥᡡᠯᠠᠨ ᡩᡝ `<fox>` ᠪᡝ ᠨᠣᠩᡤᡳ᠉ ᡥᡡᠯᠠᠨ ᡩᡝ ᡤᡳᠰᡠᡵᡝᡥᡝᡴᡡ ᡥᠠᡴᠰᠠᠨ ᠪᡝ ᠪᠠᡳᡨᠠ ᡳ ᠪᠠ ᡩᡝ ᠨᠣᠩᡤᡳᠮᠪᡳ᠉ |
| `bounding_boxes[].description` |  | string | yes |  | ≤ 500 characters | ᡩᠠᠯᠵᡳᠨ ᡳ ᠪᡠᠶᡝᠮᡝ ᠪᡝ ᠮᡠᠶᠠᠯᠠᠮᡝ, ᡩᡝᠯᡝᠨ ᡳ ᠵᠠᠩ ᠪᡝ ᡩᠠᠮᠪᠠᠨ. |
| `bounding_boxes[].box` |  | object {x_min, y_min, x_max, y_max} | yes |  |  | ᠪᡠᠶᡝᠮᡝ ᡳ ᡤᠠᠳᠠᠨ ᡩᡝ ᡩᠠᠯᠵᡳᠨ ᡳ ᠵᠠᠯᠠᠨ. |
| `bounding_boxes[].box.x_min` |  | number | yes |  | 0 – 1 | ᡩᡝᠮᡝ ᡳ ᡩᠠᠯᠵᡳᠨ, ᡤᠠᠳᠠᠨᡳ ᡠᠨᡩᡝ ᠵᠠᠯᠠᠨ ᡩᡝ ᠠᠴᠠ 0 ᡩᡝ 1. |
| `bounding_boxes[].box.y_min` |  | number | yes |  | 0 – 1 | ᡝᠮᡝᡵᡳ ᡳ ᡩᠠᠯᠵᡳᠨ, ᡤᠠᠳᠠᠨᡳ ᡝᠮᡝᡵᡳ ᡩᡝ ᠠᠴᠠ 0 ᡩᡝ 1. |
| `bounding_boxes[].box.x_max` |  | number | yes |  | 0 – 1 | ᡩᡠᠯᡝ ᡳ ᡩᠠᠯᠵᡳᠨ, ᡤᠠᠳᠠᠨᡳ ᡠᠨᡩᝡ ᠵᠠᠯᠠᠨ ᡩᡝ ᠠᠴᠠ 0 ᡩᡝ 1. |
| `bounding_boxes[].box.y_max` |  | number | yes |  | 0 – 1 | ᡩᡠᠯᡝ ᡳ ᡩᠠᠯᠵᡳᠨ, ᡤᠠᠳᠠᠨᡳ ᡝᠮᡝᡵᡳ ᡩᡝ ᠠᠴᠠ 0 ᡩᡝ 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} | ᠮᠣᡩᡝᠯ ᠪᡠᠶᡝᠮᡝᠨᡳ ᠤᠯᡥᠠᠨ ᠤᠨᠠᠰᡳᠨ᠉ |
| `timings` | object | ᠪᡠᠶᡝᠮᡝ ᡳ ᡩᠠᠩᠰᡝ ᡩᡝ ᡩᠠᠮᠪᠠᠨ. |
| `seed` | integer | ᡝᠮᡠᠯᡝᠨ ᡳ ᡝᠮᡠ ᡤᠠᠳᠠᠨᡳ ᡩᠠᠩᠰᡝ. |
| `has_nsfw_concepts` | array of boolean | ᠪᡠᠶᡝᠮᡝᠨᡳ ᠤᠯᡥᠠᠨ ᠤᠨᠠᠰᡳᠨ ᠩᡝᠮᡝ ᠪᡳ ᠰᡝᠮᡝ ᠵᠠᠯᡳᠨᠠᠮᠪᡳ᠉ |
| `prompt` | string | ᠪᡠᠶᡝᠮᡝᠨᡳ ᡥᡡᠯᠠᠨ᠉ |

## 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