Skip to main content

Uncensored — This model declares no content filter. SpicyAPI forwards the request without adding a platform content scan; legal and consent duties remain with the customer.Browse every model at this filtering level
black-forest-labs/flux-2-klein-4b-lora/edit

FLUX.2 Klein 4B LoRA image edit on Black Forest Labs' FLUX.2 [klein] 4B: change or combine up to three source images with a written instruction and up to three of your own LoRA files.

From $0.02/image
Run model

Workbench

Send a request

Quickstart

Examples use the selected endpoint’s public parameter definitions. Replace the API key and example media, then send the request from your server.

SDKs & integrations
POSThttps://api.spicyapi.ai/api/v1/jobs/createTask

API authentication

Keep the API key in the server environment variable SPICY_API_KEY. Use Bearer authentication and Content-Type: application/json for JSON requests.

Authorization: Bearer $SPICY_API_KEY
FLUX.2 Klein 4B LoRA · Image Edit · Sample output
Sample outputUse this example
# Generate the idempotency key once; reuse it when retrying after a lost response.
export SPICY_IDEMPOTENCY_KEY="${SPICY_IDEMPOTENCY_KEY:-$(uuidgen)}"
curl -X POST https://api.spicyapi.ai/api/v1/jobs/createTask \
  -H "Authorization: Bearer $SPICY_API_KEY" \
  -H "Content-Type: application/json" \
  -H "Idempotency-Key: $SPICY_IDEMPOTENCY_KEY" \
  -d '{
  "model": "black-forest-labs/flux-2-klein-4b-lora/edit",
  "input": {
    "aspect_ratio": "auto",
    "image_urls": [
      "https://example.com/reference.png"
    ],
    "prompt": "A ceramic teapot on a linen cloth, soft window light, muted palette",
    "resolution": "1k"
  }
}'

# Copy data.taskId from the response into TASK_ID, then poll the status.
TASK_ID="TASK_ID_FROM_RESPONSE"
curl "https://api.spicyapi.ai/api/v1/jobs/recordInfo?taskId=$TASK_ID" \
  -H "Authorization: Bearer $SPICY_API_KEY"

Generated from this model’s input schema — the same one the API validates every request against.

Input parameters

Place these fields inside the request body’s input object. Names and types match the API. Do not assume a default when none is specified.

image_urlsarray<string>Required

One to three source images, up to 10 MB each, in the order your prompt refers to them. Required. The price is the same for one, two or three.

Default
Not specified
Constraints
minItems:1
maxItems:3
promptstringRequired

Say what should change and what must stay the same, up to 5,000 characters. With several sources, refer to them as image 1, image 2 and image 3. Put a LoRA trigger phrase first. Required.

Default
Not specified
Constraints
minLength:1
maxLength:5000
seedintegerOptional

A number from 0 to 2147483647. Reuse it to compare edits while you change one detail of the prompt; it does not promise identical pixels.

Default
Not specified
Constraints
minimum:0
maximum:2147483647
lorasarray<object>Optional

Up to three {path, scale} entries trained for FLUX.2 [klein] 4B or Base 4B. The path must download the .safetensors file itself; scale runs from 0 to 4 (default 1). Does not change the price.

Default
[]
Constraints
maxItems:3
resolutionstringOptional

1k (default) or 2k, which is 2048 pixels on the long side. It only applies when you choose a ratio; with auto the size is about one megapixel. Both cost the same.

Default
"1k"
Allowed values
"1k""2k"
aspect_ratiostringOptional

Auto (default) keeps the shape of the first source at about one megapixel. Pick one of nine ratios from 21:9 to 9:21 to reframe the result. The ratio does not change the price.

Default
"auto"
Allowed values
"auto""1:1""16:9""9:16""4:3""3:4""3:2""2:3""21:9""9:21"

Track the task

HTTP 202 means the task was accepted, not completed. Save the returned taskId and query that task. Do not create another task while waiting for its result.

Accepted response
HTTP/1.1 202 Accepted
Location: /api/v1/jobs/recordInfo?taskId=job_01k3m8x9q2z4v7n5p6r8s0t1w3

{
  "code": 200,
  "msg": "success",
  "request_id": "req_example_create",
  "data": {
    "taskId": "job_01k3m8x9q2z4v7n5p6r8s0t1w3",
    "state": "queued",
    "estimatedCost": "0.750000"
  }
}

The accepted response includes the estimate so your app can show the same amount in task history and billing.

Read the job
curl --get "https://api.spicyapi.ai/api/v1/jobs/recordInfo" \
  --data-urlencode "taskId=$TASK_ID" \
  -H "Authorization: Bearer $SPICY_API_KEY"

Start polling at about 2 seconds and gradually increase the interval. Stop at a terminal state. After a connection failure, query the original taskId. Retry creation only with the original idempotency key and body.

Or let the callback find you
import { verifyWebhook } from "@spicyapi/sdk";

// express.raw keeps the bytes we signed; express.json never matches.
app.post("/hooks/spicy", express.raw({ type: "application/json" }), (req, res) => {
  const { payload } = verifyWebhook({
    rawBody: req.body,
    timestamp: req.header("X-Webhook-Timestamp"),
    signature: req.header("X-Webhook-Signature"),
    payloadVersion: Number(req.header("X-Webhook-Payload-Version")),
    secret: process.env.SPICY_WEBHOOK_SECRET,
  });
  res.status(200).end();
  void handleFinishedTask(payload);
});

Pass callBackUrl when you create the task and the finished record is POSTed to you — no polling loop at all. Every delivery carries X-Webhook-Timestamp, X-Webhook-Signature and X-Webhook-Payload-Version. The signature is a base64 HMAC-SHA256 over taskId.timestamp.sha256(body), so it must be checked against the raw bytes: parsing the JSON and re-serialising it changes them and the check will fail. Failed deliveries are retried, so the same taskId can arrive twice — make the handler idempotent. Answer 2xx first and do the work afterwards; a slow handler is treated as a failed delivery.

Read the result

Consume output only when state is succeeded. On failure, use errorCode, errorMessage and request_id to investigate. Example costs and states do not represent an actual bill.

Completed response example
{
  "code": 200,
  "msg": "success",
  "request_id": "req_example_record",
  "data": {
    "taskId": "job_01k3m8x9q2z4v7n5p6r8s0t1w3",
    "model": "black-forest-labs/flux-2-klein-4b-lora/edit",
    "state": "succeeded",
    "output": {
      "assets": [
        {
          "key": "tasks/2026/08/28/job_01k3m8x9q2z4v7n5p6r8s0t1w3/3f7a1c9e5b2d48f0a6c1e3d5b7f9a1c3.png",
          "mime": "image/png",
          "url": "https://example.r2.cloudflarestorage.com/results/job_01k3m8x9q2z4v7n5p6r8s0t1w3/result.png?X-Amz-Signature=SIGNATURE_FROM_RESPONSE",
          "expiresAt": "2026-08-28T12:20:08.000Z"
        }
      ]
    },
    "cost": "0.750000",
    "settled": true,
    "createdAt": "2026-08-28T12:00:00Z",
    "completedAt": "2026-08-28T12:00:30Z"
  }
}

For each available asset, open or download assets[].url directly without an API Authorization header. The signed URL expires at expiresAt; poll the task again to refresh it while the asset remains within its retention period. A pending or unavailable asset has no URL. Treat signed URLs as private.

SDKs & integrations

Use SpicyAPI in your app, terminal, AI assistant or visual workflow. Choose a setup guide below.

SDKs
TypeScript · Python · Go · PHP · Java
CLI
Terminal commands and automation scripts.
MCP
Claude Code · Cursor · Codex
Agent Skill
Reusable instructions for your AI assistant.
n8n
Self-hosted community nodes and importable HTTP Request templates for n8n Cloud.
ComfyUI
Image, video and audio workflows on a node canvas.

More integrations

SillyTavernTelegram / DiscordApp proxyOpenAI SDKLangChainVercel AI SDK
Browse ready-to-use workflows

Use it in ComfyUI

Install the SpicyAPI nodes from ComfyUI Manager or with the command below, then search for FLUX.2 Klein 4B LoRA · Image Edit on the canvas. The node has the same options as this page and shows its price before it runs.

cd ComfyUI/custom_nodes
git clone https://github.com/spicyapi-ai/comfyui-spicyapi
Workflow examplesSetup guideSource on GitHub