Generate 1K, 2K, and 4K images with the FLUX 3 Klein API. Set aspect ratio, output format, prompt enhancement, seed, and image count from one endpoint.
Generate images with Black Forest Labs FLUX 3 Klein through a single asynchronous API. Choose 1K, 2K, or 4K output, nine aspect ratios, PNG/JPEG/WebP format, prompt enhancement, and up to four images per request.
About this model
The FLUX 3 Klein text-to-image API turns a prompt into one to four images through an asynchronous REST endpoint. Choose 1K, 2K, or 4K output, nine aspect ratios, PNG/JPEG/WebP, and optional prompt enhancement or a seed. It is a simple route for product visuals, concept art, campaign assets, and rapid creative iteration. Compare the wider FLUX Klein API lineup with the FLUX.2 models on FLUX.2 and other FLUX 3 capabilities on FLUX 3.
Cost analysis
| Provider | Cost | Notes |
|---|---|---|
| muapiapp | $0.009 / $0.014 / $0.036 per image (1K / 2K / 4K) | One asynchronous endpoint; total scales with num_images. |
| Fal.ai | $0.009 / $0.014 / $0.036 per image (1K / 2K / 4K) | Matches the planned pricing schedule shown in the supplied reference screenshot. |
| Replicate | Not compared | No current like-for-like public rate was verified for this page. |
One asynchronous endpoint; total scales with num_images.
Matches the planned pricing schedule shown in the supplied reference screenshot.
No current like-for-like public rate was verified for this page.
** Competitor pricing is estimated based on similar model architectures and usage tiers.
Configuration schema
| Parameter | Type | Description | Default |
|---|---|---|---|
| Prompt | string | Describe the image or the edit to apply (up to 5,000 characters). | A sculptural glass perfume bottle on a warm limestone plinth, soft editorial light, crisp product photography. |
| Aspect Ratio | Enum (9 options) | Output framing. | 1:1 |
| Resolution | Enum (3 options) | Requested output resolution. | 1K |
| Output Format | Enum (3 options) | Image encoding for each generated output. | png |
| Number of Images | integer | Number of images to generate (1–4). Price is charged per output image. | 1 |
| Seed | integer | Optional reproducibility seed. | - |
| Enhance Prompt | boolean | Let the model refine the prompt before generation. | true |
Describe the image or the edit to apply (up to 5,000 characters).
A sculptural glass perfume bottle on a warm limestone plinth, soft editorial light, crisp product photography.Output framing.
1:1Requested output resolution.
1KImage encoding for each generated output.
pngNumber of images to generate (1–4). Price is charged per output image.
1Optional reproducibility seed.
-Let the model refine the prompt before generation.
trueDeveloper documentation
Write a prompt. Describe the subject, composition, lighting, style, and details you want. The prompt can contain up to 5,000 characters.
Choose output settings. Select resolution (1K, 2K, or 4K), aspect_ratio, output_format, and num_images (1–4). Set seed to repeat a variation and use enhance_prompt to let the model refine your prompt. Pricing is per output image: $0.009 at 1K, $0.014 at 2K, and $0.036 at 4K.
Submit and retrieve the result.
curl -X POST https://api.muapi.ai/api/v1/flux-3-klein-text-to-image \
-H "x-api-key: YOUR_API_KEY" \
-H "Content-Type: application/json" \
-d '{"prompt":"A sculptural glass perfume bottle on a warm limestone plinth, soft editorial light","resolution":"2K","aspect_ratio":"4:3","num_images":2}'
# Poll the asynchronous task
curl https://api.muapi.ai/api/v1/predictions/REQUEST_ID/result \
-H "x-api-key: YOUR_API_KEY"
The result contains an outputs array of image URLs. For image-guided changes, use the FLUX 3 Klein edit endpoint.
Frequently asked
It is an asynchronous image generation API for FLUX 3 Klein. Submit a text prompt and choose output resolution, aspect ratio, image format, and other supported settings.
Choose 1K, 2K, or 4K. The selected resolution determines the per-image price.
Muapi charges $0.009 per 1K image, $0.014 per 2K image, and $0.036 per 4K image. A request for multiple outputs is charged per output image.
Yes. Set `num_images` from 1 to 4. The returned `outputs` array contains the generated image URLs.
The text-to-image endpoint supports 1:1, 4:3, 3:4, 3:2, 2:3, 16:9, 9:16, 21:9, and 9:21. Outputs can be PNG, JPEG, or WebP.