Yapper Developer Docs

POST /api/v1/processes with "type": "image-generation". Pick any model — the API does not plan-gate models. GET /api/v1/models returns the same capabilities at runtime.

Input fields

Field	Type	Required	Description
`prompt`	`string`	yes	What to generate.
`aspectRatio`	`string`	no	One of the model's aspect ratios, e.g. "16:9".
`imageResolution`	`string`	no	One of the model's resolutions, e.g. "1080" or "4k".
`maskUrl`	`string`	no	Inpainting mask URL (white = regenerate) for edit models.
`promptUpsampling`	`boolean`	no	Let the provider expand the prompt before generating.
`referenceImages`	`{docId, url}[]`	no	Yapper image assets. Use the id + url from /assets, a process output, or /assets/import — passing docId preserves asset lineage.
`referenceImageUrls`	`string[]`	no	Plain https image URLs to guide/edit with. External URLs are imported into your asset library first (validated + stored); Yapper asset URLs pass through untouched.

Referencing media: referenceImageUrls takes plain https URLs (external images). The reference* asset fields take docId + url pairs pointing at Yapper assets — use the id and url returned by GET /assets, a completed process output, or POST /assets/import. Prefer the asset form when the media lives in Yapper: the docId preserves asset lineage.

Example

Add "dryRun": true to get the exact credit cost without starting, and always send an Idempotency-Key header on real starts.

POST /api/v1/processes
{
  "type": "image-generation",
  "model": "grok-imagine-image",
  "input": {
    "prompt": "A polished product photo of a stainless steel water bottle",
    "aspectRatio": "1:1",
    "imageResolution": "1080"
  }
}

Models at a glance

Credits are per generated output; ranges span the supported resolutions/lengths (exact prices in each model's section).

Model	Company	Credits	Resolutions	Max ref images
`nano-banana-pro`	google	10–28	720, 1080, 2k, 4k	14
`nano-banana-2`	google	8–22	720, 1080, 2k, 4k	14
`gemini-image`	google	8–10	720, 1080	3
`gpt-image-2`	openai	10–20	720, 1080, 2k, 4k	8
`gpt-image-2-high`	openai	20–60	720, 1080, 2k, 4k	8
`seedream-v4.5`	bytedance	8–20	1080, 2k, 4k	4
`grok-imagine-image`	xai	6	1080, 2k	4
`flux-2-pro`	black-forest-labs	10–20	1080, 2k	4

Nano Banana Pro (nano-banana-pro)

Google's advanced image generation and editing model.


Credits	720: 10 · 1080: 14 · 2k: 20 · 4k: 28
Aspect ratios	auto, 1:1, 16:9, 9:16, 3:4, 4:3 (default 1:1)
Resolutions	720, 1080, 2k, 4k
Reference images	up to 14

Nano Banana 2 (nano-banana-2)

Google's latest and leading image model.


Credits	720: 8 · 1080: 12 · 2k: 18 · 4k: 22
Aspect ratios	auto, 1:1, 16:9, 9:16, 3:4, 4:3 (default 1:1)
Resolutions	720, 1080, 2k, 4k
Reference images	up to 14

Nano Banana (gemini-image)

Google's legacy image model with quick generation times.


Credits	720: 8 · 1080: 10
Aspect ratios	auto, 1:1, 16:9, 9:16, 3:4, 4:3 (default 16:9)
Resolutions	720, 1080
Reference images	up to 3

GPT Image 2 (gpt-image-2)

Strong image generation and editing model with good text rendering, instruction following, and balanced cost.


Credits	720: 10 · 1080: 10 · 2k: 10 · 4k: 20
Aspect ratios	auto, 1:1, 16:9, 9:16, 3:4, 4:3, 3:2, 2:3 (default 4:3)
Resolutions	720, 1080, 2k, 4k
Reference images	up to 8

GPT Image 2 High Effort (gpt-image-2-high)

Best-in-class higher-effort GPT Image 2 for stronger fidelity and more deliberate final outputs.


Credits	720: 20 · 1080: 20 · 2k: 30 · 4k: 60
Aspect ratios	auto, 1:1, 16:9, 9:16, 3:4, 4:3, 3:2, 2:3 (default 4:3)
Resolutions	720, 1080, 2k, 4k
Reference images	up to 8

Seedream-V4.5 (seedream-v4.5)

Bytedance's advanced image generation model.


Credits	1080: 8 · 2k: 10 · 4k: 20
Aspect ratios	auto, 1:1, 16:9, 9:16, 3:4, 4:3 (default 16:9)
Resolutions	1080, 2k, 4k
Reference images	up to 4

Grok Image (grok-imagine-image)

xAI's image generation and editing model.


Credits	1080: 6 · 2k: 6
Aspect ratios	auto, 1:1, 16:9, 9:16, 4:3, 3:4, 3:2, 2:3 (default 1:1)
Resolutions	1080, 2k
Reference images	up to 4

Flux.2 Pro (flux-2-pro)

Flux's advanced image generation model.


Credits	1080: 10 · 2k: 20
Aspect ratios	auto, 1:1, 16:9, 9:16, 3:4, 4:3, 2:3, 3:2 (default 16:9)
Resolutions	1080, 2k
Reference images	up to 4

Image generation