Nano Banana 2.1

Endpoint

POST https://api.roasos.com/v1/image/nano-banana-2.1

Send your API key as a bearer token. The key needs the scope api:write. Every paid request also needs an Idempotency-Key header.

The envelope fields quote_only, quote_id, webhook_url and wait_timeout_seconds behave the same on each model endpoint. Refer to Jobs and Quotes and credits.

Good at

Nano Banana 2.1 is Google's fast image generation and editing model. One 1K image costs 1 credit, against 2 for Nano Banana Pro. Use it to iterate on a concept, to make many variations, and to make a maskless edit of an existing image: send the source image as the only reference, state the change in the prompt, and set aspect_ratio: "auto" so the result keeps the source shape. It accepts the same identity, product and style roles as Nano Banana Pro. It does not do masked inpaint. Use Nano Banana Pro when the result is a final hero asset or when 4K output must hold fine detail.

Pricing

The unit is one image. Pricing key: nano-banana-2.1.

The credits come from the roasOS pricing table. No other field changes the price. To get the exact price of your request, send it with quote_only: true first.

Modes

• text-to-image
• edit

roasOS selects the mode from the media fields of your request. You do not send a mode.

Provider endpoints: google/nano-banana-2.1 · google/nano-banana-2.1/edit.

Request fields

The schema is strict. A field that is not in this table gets 400 unsupported_option. The field names are the roasOS role names. One role has one name in every family.

Media

This endpoint accepts these media roles:

• avatar_id — identity; the saved character reference sheet, with a derived portrait only where the model requires a single face or source frame
• product_id — product; resolves to the product image list
• product_images — product reference images
• references — style and appearance references

Every other role is refused: elements, reference_images, image_url, end_image_url, scene_id, scene_image, video_urls, video_url, audio_urls, audio_url, voice_id. A refused role gets 400 unsupported_option.

Prompt

Limit: 8,000 characters for the caller; the wrapper counts toward the 10,000-character engine cap. No tag syntax; the worker orders the references and names the roles.

• Write one scene description with the camera, the light and the material named.
• For an edit, state the change only ("replace the sky with an overcast sky; keep everything else"), and set aspect_ratio: "auto".
• Put identity and product rules in the media roles, not in the prompt text.
• Iterate here, then rerun the winning prompt on Nano Banana Pro for the final asset.
• Give rendered text inside quotation marks.

Not exposed

These catalog entries describe omitted inputs, pinned values and source constraints. They do not imply that the provider accepts every listed field.

• output_format — pinned to png.
• safety_tolerance — not accepted by this public endpoint.
• enable_web_search — pinned to false.
• limit_generations — pinned to true.
• system_prompt — not accepted by this public endpoint.
• sync_mode — not accepted by this public endpoint.
• thinking_level — not accepted by this public endpoint.
• video_url — not accepted by this public endpoint.
• audio_url — not accepted by this public endpoint.
• pdf_url — not accepted by this public endpoint.

Result

The result kind is image. Always present: nothing. Present when the run makes it: avatar_id, full_body_url, images, portrait_url, provider_seed, reference_sheet, url.

{
  "data": {
    "id": "gen_…",
    "kind": "image",
    "model": "nano-banana-2.1",
    "status": "completed",
    "result": {
      "avatar_id": "00000000-0000-4000-8000-000000000000",
      "full_body_url": "https://cdn.roasos.com/workspaces/ws_01/full_body_url",
      "images": [
        "https://cdn.roasos.com/workspaces/ws_01/images-1.png"
      ],
      "portrait_url": "https://cdn.roasos.com/workspaces/ws_01/portrait_url",
      "provider_seed": 0,
      "reference_sheet": "https://cdn.roasos.com/workspaces/ws_01/reference_sheet",
      "url": "https://cdn.roasos.com/workspaces/ws_01/result"
    }
  }
}

The files are immutable objects on https://cdn.roasos.com. A result URL is a valid media input for your next request.

Example

The three steps are always the same: quote, run, poll.

# 1. Quote. Nothing is spent.
curl -X POST https://api.roasos.com/v1/image/nano-banana-2.1 \
  -H "Authorization: Bearer roasos_sk_live_..." \
  -H "Idempotency-Key: 0f1c9e2a-nano-banana-2.1-0001" \
  -H "Content-Type: application/json" \
  -d '{"quote_only":true,"prompt":"A woman holds the bottle at eye level in a bright kitchen, morning light, static camera."}'
# 200 { "data": { "kind": "quote", "quote_id": "q_7Hk...", "credits": 1, "expires_at": "...",
#        "confirmation": { "model": "nano-banana-2.1", "example": "1_image_1K" } } }

# 2. Run. Same body, same Idempotency-Key, quote_id in place of quote_only.
curl -X POST https://api.roasos.com/v1/image/nano-banana-2.1 \
  -H "Authorization: Bearer roasos_sk_live_..." \
  -H "Idempotency-Key: 0f1c9e2a-nano-banana-2.1-0001" \
  -H "Content-Type: application/json" \
  -d '{"quote_id":"q_7Hk...","prompt":"A woman holds the bottle at eye level in a bright kitchen, morning light, static camera."}'
# 201 { "data": { "id": "gen_...", "status": "queued", "credits_reserved": 1 } }

# 3. Poll, then read the result.
curl https://api.roasos.com/v1/jobs/gen_.../status -H "Authorization: Bearer roasos_sk_live_..."
curl https://api.roasos.com/v1/jobs/gen_.../result -H "Authorization: Bearer roasos_sk_live_..."

The deprecated path

POST /v1/generations still reaches this model for one minor version. It is deprecated. This is how it maps:

POST /v1/generations { "type": "image", "model": "nano-banana-2.1", "prompt": "…", "options": { "aspect_ratio", "resolution", "num_outputs", "reference_images" (≤ 9), "seed" } }. No avatar_id, product_images or product_id role today; the prompt is sent raw. The resolution values are 1K, 2K and 4K. The default is 1K. Today's aspect_ratio list is auto, 9:16, 1:1, 3:4, 4:3, 16:9, 21:9.

See also

• llms.txt for this model — the same facts as one plain-text file for an agent.
• GET https://api.roasos.com/v1/catalog/nano-banana-2.1 — the machine-readable form: enums, defaults, limits and prices. Refer to the API reference.
• Jobs — how to poll a job and read its result.
• Provider endpoints: google/nano-banana-2.1 · google/nano-banana-2.1/edit.