Use Google Imagen4 Fast through Rivya Public API v1 with model id google-imagen4-fast, supported inputs, parameters, Files API rules, credits, and response examples.

Available via APIText input readyImage

API model id

google-imagen4-fast

Inputs

text

Files API

Not required for the minimal request

Base credits

Capability

Image

Billing

FIXED

Prompt limit

5000 characters

Request contract

Send the model id at the top level. Model-specific controls belong in params.

Key	Type	Required	Default	Description
model	string	Yes	google-imagen4-fast	Use the google-imagen4-fast API model id.
prompt	string	Yes	-	Maximum 5000 characters for this model.
params	object	No	-	Model-specific parameter object. Use the rows below for allowed keys.
client_request_id	string	No	-	Optional client-side id for tracing requests in your system.

Model parameters

Key	Type	Required	Default	Range	Options	Description
aspect_ratio	select	No	16:9	-	1:1, 16:9, 9:16, 3:4, 4:3	Aspect ratio
negative_prompt	text	No	-	-	-	Negative prompt
seed	number	No	-	min 0	-	Leave it empty for a new random result each time. Reusing the same integer makes it easier to reproduce or fine-tune a previous result. It stays closer only when the prompt and other key settings also remain similar, and it is not a guaranteed 1:1 match.

Minimal request

{
  "model": "google-imagen4-fast",
  "prompt": "A clean editorial product image on a soft studio background",
  "params": {
    "aspect_ratio": "16:9",
    "negative_prompt": "Optional things to avoid",
    "seed": 0
  }
}

Create response

The create endpoint returns a public task id. Poll the status endpoint until the task succeeds or fails.

{
  "id": "task_google_imagen4_fast_example",
  "status": "queued",
  "model": "google-imagen4-fast",
  "reserved_credits": 4,
  "final_credits": 0,
  "created_at": "2026-05-11T00:00:00.000Z",
  "updated_at": "2026-05-11T00:00:00.000Z",
  "result": null,
  "error": null
}

Common errors

validation_failed, insufficient_credits, idempotency_conflict, rate_limited, not_found