flux-2-flex

Generate an image from a text prompt using FLUX.2 [flex]. Offers fine-grained control over inference steps and guidance scale. Returns the result synchronously as base64-encoded JSON.

POST /v1/images/generations

Text-to-Image Generation

cURL

curl --request POST \
  --url https://www.anyfast.ai/v1/images/generations \
  --header 'Authorization: Bearer <token>' \
  --header 'Content-Type: application/json' \
  --data '
{
  "model": "flux-2-flex",
  "prompt": "A cute baby polar bear",
  "n": 1,
  "size": "1024x1024",
  "inference_steps": 25,
  "guidance_scale": 5.75,
  "output_format": "jpeg",
  "seed": 123
}
'

import requests

url = "https://www.anyfast.ai/v1/images/generations"

payload = {
    "model": "flux-2-flex",
    "prompt": "A cute baby polar bear",
    "n": 1,
    "size": "1024x1024",
    "inference_steps": 25,
    "guidance_scale": 5.75,
    "output_format": "jpeg",
    "seed": 123
}
headers = {
    "Authorization": "Bearer <token>",
    "Content-Type": "application/json"
}

response = requests.post(url, json=payload, headers=headers)

print(response.text)

const options = {
  method: 'POST',
  headers: {Authorization: 'Bearer <token>', 'Content-Type': 'application/json'},
  body: JSON.stringify({
    model: 'flux-2-flex',
    prompt: 'A cute baby polar bear',
    n: 1,
    size: '1024x1024',
    inference_steps: 25,
    guidance_scale: 5.75,
    output_format: 'jpeg',
    seed: 123
  })
};

fetch('https://www.anyfast.ai/v1/images/generations', options)
  .then(res => res.json())
  .then(res => console.log(res))
  .catch(err => console.error(err));

<?php

$curl = curl_init();

curl_setopt_array($curl, [
  CURLOPT_URL => "https://www.anyfast.ai/v1/images/generations",
  CURLOPT_RETURNTRANSFER => true,
  CURLOPT_ENCODING => "",
  CURLOPT_MAXREDIRS => 10,
  CURLOPT_TIMEOUT => 30,
  CURLOPT_HTTP_VERSION => CURL_HTTP_VERSION_1_1,
  CURLOPT_CUSTOMREQUEST => "POST",
  CURLOPT_POSTFIELDS => json_encode([
    'model' => 'flux-2-flex',
    'prompt' => 'A cute baby polar bear',
    'n' => 1,
    'size' => '1024x1024',
    'inference_steps' => 25,
    'guidance_scale' => 5.75,
    'output_format' => 'jpeg',
    'seed' => 123
  ]),
  CURLOPT_HTTPHEADER => [
    "Authorization: Bearer <token>",
    "Content-Type: application/json"
  ],
]);

$response = curl_exec($curl);
$err = curl_error($curl);

curl_close($curl);

if ($err) {
  echo "cURL Error #:" . $err;
} else {
  echo $response;
}

package main

import (
	"fmt"
	"strings"
	"net/http"
	"io"
)

func main() {

	url := "https://www.anyfast.ai/v1/images/generations"

	payload := strings.NewReader("{\n  \"model\": \"flux-2-flex\",\n  \"prompt\": \"A cute baby polar bear\",\n  \"n\": 1,\n  \"size\": \"1024x1024\",\n  \"inference_steps\": 25,\n  \"guidance_scale\": 5.75,\n  \"output_format\": \"jpeg\",\n  \"seed\": 123\n}")

	req, _ := http.NewRequest("POST", url, payload)

	req.Header.Add("Authorization", "Bearer <token>")
	req.Header.Add("Content-Type", "application/json")

	res, _ := http.DefaultClient.Do(req)

	defer res.Body.Close()
	body, _ := io.ReadAll(res.Body)

	fmt.Println(string(body))

}

HttpResponse<String> response = Unirest.post("https://www.anyfast.ai/v1/images/generations")
  .header("Authorization", "Bearer <token>")
  .header("Content-Type", "application/json")
  .body("{\n  \"model\": \"flux-2-flex\",\n  \"prompt\": \"A cute baby polar bear\",\n  \"n\": 1,\n  \"size\": \"1024x1024\",\n  \"inference_steps\": 25,\n  \"guidance_scale\": 5.75,\n  \"output_format\": \"jpeg\",\n  \"seed\": 123\n}")
  .asString();

require 'uri'
require 'net/http'

url = URI("https://www.anyfast.ai/v1/images/generations")

http = Net::HTTP.new(url.host, url.port)
http.use_ssl = true

request = Net::HTTP::Post.new(url)
request["Authorization"] = 'Bearer <token>'
request["Content-Type"] = 'application/json'
request.body = "{\n  \"model\": \"flux-2-flex\",\n  \"prompt\": \"A cute baby polar bear\",\n  \"n\": 1,\n  \"size\": \"1024x1024\",\n  \"inference_steps\": 25,\n  \"guidance_scale\": 5.75,\n  \"output_format\": \"jpeg\",\n  \"seed\": 123\n}"

response = http.request(request)
puts response.read_body

200

{
  "created": 1774002799,
  "data": [
    {
      "b64_json": "<string>"
    }
  ]
}

Authorizations

Authorization · string · header · required

Bearer authentication header of the form Bearer <token>, where <token> is your auth token.

Body

application/json

model · enum<string> · required

Model ID

Available options: flux-2-flex

Example:

"flux-2-flex"

prompt · string · required

Text description of the image to generate.

Example:

"A cute baby polar bear"

n · integer · default: 1

Number of images to generate.

Required range: 1 <= x <= 4

size · string

Output image size, e.g. 1024x1024. Supports up to 4MP resolution.

Example:

"1024x1024"

inference_steps · integer

Number of sampling steps. Low (6–20) for fast prototyping, high (40–50) for maximum fidelity.

Required range: 1 <= x <= 50

guidance_scale · number

Guidance scale. Controls how closely the model follows the prompt. Higher values produce more prompt-faithful results.

Required range: 1.5 <= x <= 10

output_format · enum<string>

Output image format.

Available options: jpeg, png

Example:

"jpeg"

seed · integer

Random seed for reproducible generation.

Response

200

application/json

Image generated successfully

created · integer

Example:

1774002799

data · object[]

Show child attributes