Generate an image from a detailed caption with the step-distilled model.
The client provides a convenient way to interact with the model API.
npm install --save @fal-ai/clientThe @fal-ai/serverless-client package has been deprecated in favor of @fal-ai/client. Install the new package and update your imports — see client setup.
Set FAL_KEY as an environment variable in your runtime.
export FAL_KEY="YOUR_API_KEY"The client API handles the API submit protocol. It will handle the request status updates and return the result when the request is completed.
import { fal } from "@fal-ai/client";
const result = await fal.subscribe("blackforestlabs/flux-3/klein/text-to-image", {
input: {
prompt: "A red fox standing in fresh snow at sunrise, its breath visible in the cold air. Soft golden light rakes across the snowfield from the left, pine forest softly blurred in the background, shot at eye level with a telephoto lens."
},
logs: true,
onQueueUpdate: (update) => {
if (update.status === "IN_PROGRESS") {
update.logs.map((log) => log.message).forEach(console.log);
}
},
});
console.log(result.data);
console.log(result.requestId);The API uses an API Key for authentication. It is recommended you set the FAL_KEY environment variable in your runtime when possible.
import { fal } from "@fal-ai/client";
fal.config({
credentials: "YOUR_FAL_KEY"
});When running code on the client-side (e.g. in a browser, mobile app or GUI applications), make sure to not expose your FAL_KEY. Instead, use a server-side proxy to make requests to the API. For more information, check out our server-side integration guide.
The client API provides a convenient way to submit requests to the model.
import { fal } from "@fal-ai/client";
const { request_id } = await fal.queue.submit("blackforestlabs/flux-3/klein/text-to-image", {
input: {
prompt: "A red fox standing in fresh snow at sunrise, its breath visible in the cold air. Soft golden light rakes across the snowfield from the left, pine forest softly blurred in the background, shot at eye level with a telephoto lens."
},
webhookUrl: "https://optional.webhook.url/for/results",
});You can fetch the status of a request to check if it is completed or still in progress.
import { fal } from "@fal-ai/client";
const status = await fal.queue.status("blackforestlabs/flux-3/klein/text-to-image", {
requestId: "764cabcf-b745-4b3e-ae38-1200304cf45b",
logs: true,
});Once the request is completed, you can fetch the result. See the Output Schema for the expected result format.
import { fal } from "@fal-ai/client";
const result = await fal.queue.result("blackforestlabs/flux-3/klein/text-to-image", {
requestId: "764cabcf-b745-4b3e-ae38-1200304cf45b"
});
console.log(result.data);
console.log(result.requestId);Some attributes in the API accept file URLs as input. Whenever that's the case you can pass your own URL or a Base64 data URI.
You can pass a Base64 data URI as a file input. The API will handle the file decoding for you. Keep in mind that for large files, this alternative although convenient can impact the request performance.
You can also pass your own URLs as long as they are publicly accessible. Be aware that some hosts might block cross-site requests, rate-limit, or consider the request as a bot.
We provide a convenient file storage that allows you to upload files and use them in your requests. You can upload files using the client API and use the returned URL in your requests.
import { fal } from "@fal-ai/client";
const file = new File(["Hello, World!"], "hello.txt", { type: "text/plain" });
const url = await fal.storage.upload(file);The client will auto-upload the file for you if you pass a binary object (e.g. File, Data).
Read more about file handling in our file upload guide.
prompt string* requiredThe prompt to generate an image from. The model is trained on detailed captions: describe framing, subject, background and lighting.
enable_prompt_expansion booleanIf set to true, the prompt is expanded into a detailed caption (grounded in the reference images when editing) before generation. Default value: true
seed integerThe same seed and the same prompt given to the same version of the model will output the same image every time.
num_images integerThe number of images to generate. Default value: 1
enable_safety_checker booleanIf set to true, the safety checker will be enabled. Default value: true
output_format OutputFormatEnumThe format of the generated image. Default value: "png"
Possible enum values: jpeg, png, webp
sync_mode booleanIf True, the media will be returned as a data URI and the output data won't be available in the request history.
The size of the generated image. Each side can be 256 to 4096 pixels (native 4K). Default value: square_hd
Possible enum values: square_hd, square, portrait_4_3, portrait_16_9, landscape_4_3, landscape_16_9
Note: For custom image sizes, you can pass the width and height as an object:
"image_size": {
"width": 1280,
"height": 720
}Optional layout: draw each described object inside its box. Box edges are fractions of the image size, with (0, 0) at the top-left. Name boxes in the prompt by label, e.g. A red fox <fox> sits under a red umbrella <umbrella>.
{
"prompt": "A red fox standing in fresh snow at sunrise, its breath visible in the cold air. Soft golden light rakes across the snowfield from the left, pine forest softly blurred in the background, shot at eye level with a telephoto lens.",
"enable_prompt_expansion": true,
"num_images": 1,
"enable_safety_checker": true,
"output_format": "png",
"image_size": "square_hd",
"bounding_boxes": [
{
"label": "fox",
"description": "a red fox with thick orange fur and a white-tipped tail",
"box": {
"x_min": 0.3,
"y_min": 0.4,
"x_max": 0.7,
"y_max": 0.9
}
}
]
}The generated images.
The timings of the generation process.
seed integer* requiredSeed used to generate the first image.
Whether the generated images contain NSFW concepts.
prompt string* requiredThe prompt used for generating the image.
{
"images": [
{
"url": "",
"content_type": "image/png",
"file_name": "z9RV14K95DvU.png",
"file_size": 4404019
}
],
"prompt": ""
}width integerThe width of the generated image. Default value: 512
height integerThe height of the generated image. Default value: 512
label stringShort name for the object in this box, e.g. fox. Write <fox> in the prompt to tie the box to those words; a box the prompt doesn't name is added to the scene. Defaults to obj_<n>.
description string* requiredWhat to draw in this box: the object and its look.
Where the object goes in the output image.
url string* requiredThe URL where the file can be downloaded from.
content_type stringThe mime type of the file.
file_name stringThe name of the file. It will be auto-generated if not provided.
file_size integerThe size of the file in bytes.
width integerThe width of the image
height integerThe height of the image
x_min float* requiredLeft edge as a fraction of the image width (0-1).
y_min float* requiredTop edge as a fraction of the image height (0-1).
x_max float* requiredRight edge as a fraction of the image width (0-1).
y_max float* requiredBottom edge as a fraction of the image height (0-1).