Generates images from a text prompt. Image models have category: "IMAGE" in GET /v1/models.
Returns
url expires after 10 minutes. Within 24 hours you can get a new link from GET /v1/outputs/{requestId} using this response's x-request-id header, so save it.
Body
modelstringYesIMAGEmodel IDpromptstringYes- 1–16,000 characters. Providers with lower limits may reject longer prompts
nintegerNo- 1–10. Default 1
sizestringNoWxHpixels (such as256x256,512x512,1024x1024,1792x1024,1024x1792,1536x1024,1024x1536),auto, or aresolutiontier. Pixels win; a conflictingaspect_ratioorresolutionreturns 400aspect_ratiostringNo1:1,16:9,9:16,4:3,3:4,3:2,2:3,4:5,5:4,1:2,2:1,7:5,5:7,1:4,4:1,1:8,8:1,9:21,21:9,auto(provider default)resolutionstringNo512,768,1K(≈1 MP),1.5K,2K(≈4 MP),4K(the model's largest tier)qualitystringNostandard,hd,low,medium,high,xhigh,max,auto.xhighandmax: GPT Image 2.5 only. Seelimits.supported_qualitiesresponse_formatstringNourl(default) orb64_jsonoutput_formatstringNopng,jpeg,webp. Only models withoutput_formatinparameter_profile; others return 400output_compressionintegerNo- 0–100 for
jpegandwebp. GPT Image only backgroundstringNotransparent,opaque,auto. GPT Image only.transparentneedspngorwebpmoderationstringNoloworauto. GPT Image onlyuserstringNo- End-user identifier
prompt_upsamplingbooleanNo- FLUX 3 Image Klein only. Default
true. Other models return 400 extra_body.gpunodeobjectNo- Open-weight models:
seed(same seed, same image; image i of n uses seed + i) andnum_inference_steps extra_body.googleobjectNo- deprecated.
aspect_ratioandimage_sizeare old names foraspect_ratioandresolution. Conflicting values return 400
Aspect ratio and resolution
Each model's accepted values are in parameter_profile.tasks["image-generation"].parameters.
Under the default auto policy, an unsupported ratio moves to the nearest supported one and a resolution to the nearest supported tier at or below it (or the smallest), with a note in x_everyais.parameter_warnings. strict returns 400.
- Gemini: a pixel
sizemaps to the nearest ratio and tier (3840x2160→16:9,4K). - GPT Image 2.5: tiers become
WxHon a 16 px grid (1360x768,2720x1536and3840x2160at 16:9). Custom sizes work with sides in multiples of 16 up to 3840, ratio 1:3–3:1 and 655,360–8,294,400 pixels. - Models with a size list, such as FLUX 3 Image Klein, pick by ratio, then resolution. Prices by size are in
pricing.variants[].meta.sizes.
Check limits.supported_sizes. Token-priced image models cost more at larger sizes and higher quality.
FLUX 3 Image Klein
everyais/flux-3-image-klein is a 5.6B open-weight model from Black Forest Labs.
| Option | Value |
|---|---|
n | 1–4 |
| Size | One of the 60 sizes below, or aspect_ratio + resolution. Default 1024x1024 (1:1, 1K). size: "auto" equals omitting it |
output_format | png, jpeg, webp. Default jpeg |
extra_body.gpunode.seed | 0–2147483647 |
extra_body.gpunode.num_inference_steps | 1–16. Default 16 |
prompt_upsampling | Default true: BFL's upsampler rewrites the prompt into a detailed caption, as in BFL's API. false uses your prompt as written. extra_body.gpunode.prompt_upsampling is the same switch; don't send conflicting values |
guidance_scale, negative_prompt | Not supported (400) |
With upsampling on, each response item includes the rewritten caption as revised_prompt.
Supported sizes
Resolutions are 768, 1K, 1.5K and 2K. 4K is not supported: auto lowers it to 2K and strict returns 400.
Under auto, an unlisted size becomes the largest listed size of the nearest ratio that fits inside it (1024x768 → 880x672, 1920x1080 → 1360x768), with a warning.
Sizes are never enlarged, so anything below 768x768 returns 400, as does any unlisted size under strict. The response's top-level size is the actual output size.
| Aspect ratio | 768 | 1K | 1.5K | 2K |
|---|---|---|---|---|
21:9 | 1168x496 | 1568x672 | 2352x1008 | 3136x1344 |
2:1 | 1088x544 | 1456x720 | 2176x1088 | 2896x1456 |
16:9 | 1024x576 | 1360x768 | 2048x1152 | 2736x1536 |
3:2 | 944x624 | 1248x832 | 1888x1248 | 2512x1680 |
7:5 | 912x656 | 1216x864 | 1824x1296 | 2416x1728 |
4:3 | 880x672 | 1184x880 | 1776x1328 | 2368x1776 |
5:4 | 864x688 | 1152x912 | 1712x1376 | 2288x1824 |
1:1 | 768x768 | 1024x1024 | 1536x1536 | 2048x2048 |
4:5 | 688x864 | 912x1152 | 1376x1712 | 1824x2288 |
3:4 | 672x880 | 880x1184 | 1328x1776 | 1776x2368 |
5:7 | 656x912 | 864x1216 | 1296x1824 | 1728x2416 |
2:3 | 624x944 | 832x1248 | 1248x1888 | 1680x2512 |
9:16 | 576x1024 | 768x1360 | 1152x2048 | 1536x2736 |
1:2 | 544x1088 | 720x1456 | 1088x2176 | 1456x2896 |
9:21 | 496x1168 | 672x1568 | 1008x2352 | 1344x3136 |
Pricing (per image, USD)
| Output tier | Price |
|---|---|
768 | $0.008 |
1K | $0.009 |
1.5K | $0.011 |
2K | $0.014 |
Editing costs the same. Multiply by n; your account rates apply.
Bounding-box layout
Append a JSON list to the prompt to place elements: {"id","bbox":[top,left,bottom,right],"desc"} on a 0–1000 grid. Refer to each element in the caption as <id>.
{
"model": "everyais/flux-3-image-klein",
"prompt": "A cozy cafe window scene: a <cat> sleeps on the left windowsill and a <plant> stands on the right. [{\"id\":\"cat\",\"bbox\":[500,50,900,450],\"desc\":\"orange tabby cat curled up\"},{\"id\":\"plant\",\"bbox\":[300,600,900,900],\"desc\":\"potted monstera\"}]",
"aspect_ratio": "3:2",
"resolution": "1K",
"extra_body": { "gpunode": { "seed": 42 } }
}Tips
- Describe the whole scene. There is no negative prompt, so say what should be there.
- Put text you want rendered in quotes.
- License: FLUX Kommunity License (non-commercial, plus commercial use of outputs for qualifying users). Outputs pass an NSFW filter.
Model options
Pick a model at the top of this page, or read capabilities, limits and parameter_constraints from GET /v1/models.
Parameter policy decides whether unsupported values are adjusted or rejected with 400. Omitted size, ratio, resolution and quality use the model's defaults.