# FLUX.2 [klein] 4B Base · Edit API

> Paruvel dži 4 inputo kipa le 4B Base modelosa, negativno promptosa thaj lidžaripnaski kontrolasa

Čitrengo editiripen kerdo jekhe `prompt`-estar thaj dži 4 čitrendar andro `image_urls`. Del `negative_prompt`, `guidance_scale` (0 to 20), 4 to 50 steps 28 defaultone, thaj `acceleration` none, regular vaj high. Te `image_size` na si, o inputesqo baripen si rakhlo. Pale anel 1 to 4 čitri andro png, jpeg vaj webp.

- Model id: `flux-2/klein/4b/base/edit`
- Made by: Black Forest Labs
- Category: Image Editing
- Output: image
- Price per megapixel: $0.009 / megapixel (cheapest run $0.009 (9 API credits))
- Run: `POST https://api.doitong.com/v1/run/flux-2/klein/4b/base/edit`
- Quote: `POST https://api.doitong.com/v1/quote/flux-2/klein/4b/base/edit`
- Docs page: https://doitong.com/rom/developers/models/flux-2/klein/4b/base/edit

## Pricing

Price: **$0.009 / megapixel**. Price per megapixel: 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 $0.018 = 18 API credits (2 MP × $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.com/v1/quote/flux-2/klein/4b/base/edit` 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 |  |  | Prompto savo phenel save promeni te keren pe kodo kiposke. |
| `negative_prompt` |  | string | no | `` |  | Negači prompto savo phenel so te na avel ande kipo pa classifier-free guidance. |
| `guidance_scale` |  | number | no | `5` | 0 – 20 | Skala aplikime pa classifier-free guidance. |
| `seed` |  | integer \| null | no |  |  | Kerepesqo seed override; kana na dino, o keripe alosarel jekh seed randomeste. |
| `num_inference_steps` |  | integer | no | `28` | 4 – 50 | Gin inference steps pala te kerel. |
| `image_size` |  | object {width, height} \| enum (string) \| null | no |  | `square_hd`, `square`, `portrait_4_3`, `portrait_16_9`, `landscape_4_3`, `landscape_16_9` | Dimenzije rezultatoske kipeske; kana naj, dimenzije aven sar ando inputo kipo. |
| `num_images` | `num_outputs` | integer | no | `1` | 1 – 4 | Manglo kipoqo gin vaš generiripe. |
| `acceleration` |  | enum (string) | no | `regular` | `none`, `regular`, `high` | Akseleracijako nivo aplikime andar keripe kipesko. |
| `enable_safety_checker` |  | boolean | no | `true` |  | Safety-checking savo thovel kale kipo thaneste sako unsafe kipo. True aktivarel checking; false deaktivuil la numa autorizirime kontonge, kana mangipena bi autorizacia si checking zorutno. |
| `output_format` |  | enum (string) | no | `png` | `jpeg`, `png`, `webp` | Fajlo-formato e rezultato kipoqo. |
| `image_urls` | `images` | array of image URL | yes |  |  | URL-ja kipeske vaš editaci, limitime pe 4 kipa. |

File parameters (`images`) take a public `https://` URL, a `data:` URI up to 10 MB, or the `file_url` of an upload from `POST /files`.

## Example input

Required parameters only:

```json
{
  "prompt": "A red fox trots through fresh snow at sunrise, soft golden light, shallow depth of field",
  "images": [
    "https://content.doitong.com/images/showcase/v3/gen_fox_cartoon.jpg"
  ]
}
```

A fuller example:

```json
{
  "prompt": "A red fox trots through fresh snow at sunrise, soft golden light, shallow depth of field",
  "image_urls": [
    "https://content.doitong.com/images/showcase/v3/gen_fox_cartoon.jpg"
  ]
}
```

## 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.com/v1/run/flux-2/klein/4b/base/edit?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",
    "image_urls": [
      "https://content.doitong.com/images/showcase/v3/gen_fox_cartoon.jpg"
    ]
  }'

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

### JavaScript

```javascript
const API = "https://api.doitong.com/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/flux-2/klein/4b/base/edit?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",
    "image_urls": [
      "https://content.doitong.com/images/showcase/v3/gen_fox_cartoon.jpg"
    ]
  }),
});
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.com/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",
    "image_urls": [
        "https://content.doitong.com/images/showcase/v3/gen_fox_cartoon.jpg",
    ],
}

# Run the model; wait up to 20 s for the finished result in the same call
r = requests.post(API + "/run/flux-2/klein/4b/base/edit", 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.com/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": "flux-2/klein/4b/base/edit",
      "input": {
        "prompt": "A red fox trots through fresh snow at sunrise, soft golden light, shallow depth of field",
        "image_urls": [
          "https://content.doitong.com/images/showcase/v3/gen_fox_cartoon.jpg"
        ]
      },
      "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": "flux-2/klein/4b/base/edit",
  "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": 18,
    "usd": "0.018",
    "charged": 18,
    "refunded": 0
  },
  "input": {
    "prompt": "A red fox trots through fresh snow at sunrise, soft golden light, shallow depth of field",
    "image_urls": [
      "https://content.doitong.com/images/showcase/v3/gen_fox_cartoon.jpg"
    ]
  },
  "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.com/v1/requests/req_8k2m4q7x1z9c3v5b6n0p2r4t",
    "cancel": "https://api.doitong.com/v1/requests/req_8k2m4q7x1z9c3v5b6n0p2r4t/cancel"
  }
}
```

### Output fields (`output`)

| Field | Type | Description |
|---|---|---|
| `images` | array of object {url, content_type, file_name, file_size, width, height} | Kipa save kerde editaciatar. |
| `timings` | object |  |
| `seed` | integer | Kipo-generiripeqo seed, inkludirindoj o randomno kidlo valoro kana o inputo na sas seed; averčes, repetirisar o dindo valoro. |
| `has_nsfw_concepts` | array of boolean | Sikavel te si NSFW koncepto ande generirime kipo. |
| `prompt` | string | Prompto utilizuime ko kipoqo generiripe. |

## Related models

- [FLUX.2 \[klein\] 4B](https://doitong.com/developers/models/flux-2/klein/4b.md) (`flux-2/klein/4b`): $0.005 / megapixel
- [FLUX.2 \[klein\] 4B Base](https://doitong.com/developers/models/flux-2/klein/4b/base.md) (`flux-2/klein/4b/base`): $0.009 / megapixel
- [FLUX.2 \[klein\] 9B](https://doitong.com/developers/models/flux-2/klein/9b.md) (`flux-2/klein/9b`): $0.006 / megapixel
- [FLUX.2 \[klein\] 9B Base](https://doitong.com/developers/models/flux-2/klein/9b/base.md) (`flux-2/klein/9b/base`): $0.011 / megapixel
- [FLUX.2 \[klein\] 4B · Edit](https://doitong.com/developers/models/flux-2/klein/4b/edit.md) (`flux-2/klein/4b/edit`): $0.01 / image
- [FLUX.2 \[klein\] 9B Base · Edit](https://doitong.com/developers/models/flux-2/klein/9b/base/edit.md) (`flux-2/klein/9b/base/edit`): $0.011 / megapixel
- [FLUX.2 \[klein\] 9B · Edit](https://doitong.com/developers/models/flux-2/klein/9b/edit.md) (`flux-2/klein/9b/edit`): $0.011 / megapixel
- [FLUX.1 Kontext \[pro\]](https://doitong.com/developers/models/flux-pro/kontext.md) (`flux-pro/kontext`): $0.04 / image

## Links

- HTML page: https://doitong.com/developers/models/flux-2/klein/4b/base/edit
- 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=flux-2/klein/4b/base/edit
- Errors: https://doitong.com/developers/docs/errors
- Model details as JSON: https://api.doitong.com/v1/models/flux-2/klein/4b/base/edit