Gemini 3.1 Flash Image is a text-to-image model that generates images from text descriptions.
The client provides a convenient way to interact with the model API.
npm install --save @fal-ai/clientThe @fal-ai/serverless-client package has been deprecated in favor of @fal-ai/client. Install the new package and update your imports — see client setup.
Set FAL_KEY as an environment variable in your runtime.
export FAL_KEY="YOUR_API_KEY"The client API handles the API submit protocol. It will handle the request status updates and return the result when the request is completed.
import { fal } from "@fal-ai/client";
const result = await fal.subscribe("fal-ai/gemini-3.1-flash-image-preview", {
input: {
prompt: "An action shot of a black lab swimming in an inground suburban swimming pool. The camera is placed meticulously on the water line, dividing the image in half, revealing both the dogs head above water holding a tennis ball in it's mouth, and it's paws paddling underwater."
},
logs: true,
onQueueUpdate: (update) => {
if (update.status === "IN_PROGRESS") {
update.logs.map((log) => log.message).forEach(console.log);
}
},
});
console.log(result.data);
console.log(result.requestId);The API uses an API Key for authentication. It is recommended you set the FAL_KEY environment variable in your runtime when possible.
import { fal } from "@fal-ai/client";
fal.config({
credentials: "YOUR_FAL_KEY"
});When running code on the client-side (e.g. in a browser, mobile app or GUI applications), make sure to not expose your FAL_KEY. Instead, use a server-side proxy to make requests to the API. For more information, check out our server-side integration guide.
The client API provides a convenient way to submit requests to the model.
import { fal } from "@fal-ai/client";
const { request_id } = await fal.queue.submit("fal-ai/gemini-3.1-flash-image-preview", {
input: {
prompt: "An action shot of a black lab swimming in an inground suburban swimming pool. The camera is placed meticulously on the water line, dividing the image in half, revealing both the dogs head above water holding a tennis ball in it's mouth, and it's paws paddling underwater."
},
webhookUrl: "https://optional.webhook.url/for/results",
});You can fetch the status of a request to check if it is completed or still in progress.
import { fal } from "@fal-ai/client";
const status = await fal.queue.status("fal-ai/gemini-3.1-flash-image-preview", {
requestId: "764cabcf-b745-4b3e-ae38-1200304cf45b",
logs: true,
});Once the request is completed, you can fetch the result. See the Output Schema for the expected result format.
import { fal } from "@fal-ai/client";
const result = await fal.queue.result("fal-ai/gemini-3.1-flash-image-preview", {
requestId: "764cabcf-b745-4b3e-ae38-1200304cf45b"
});
console.log(result.data);
console.log(result.requestId);Some attributes in the API accept file URLs as input. Whenever that's the case you can pass your own URL or a Base64 data URI.
You can pass a Base64 data URI as a file input. The API will handle the file decoding for you. Keep in mind that for large files, this alternative although convenient can impact the request performance.
You can also pass your own URLs as long as they are publicly accessible. Be aware that some hosts might block cross-site requests, rate-limit, or consider the request as a bot.
We provide a convenient file storage that allows you to upload files and use them in your requests. You can upload files using the client API and use the returned URL in your requests.
import { fal } from "@fal-ai/client";
const file = new File(["Hello, World!"], "hello.txt", { type: "text/plain" });
const url = await fal.storage.upload(file);The client will auto-upload the file for you if you pass a binary object (e.g. File, Data).
Read more about file handling in our file upload guide.
prompt string* requiredThe text prompt to generate an image from.
Previous native Gemini turns, including original parts and thought signatures from conversations. The current prompt starts a new user turn.
context list<GeminiTextPart | GeminiImagePart | GeminiDocumentPart | GeminiVideoPart | GeminiSignaturePart>Ordered text, image, PDF, UTF-8 text-file or video parts appended to the current prompt. Original media bytes are preserved; images count toward the total 14-reference limit.
return_history booleanReturn reusable native conversations with original image parts and provider thought signatures. Uses a native provider. Each generated conversation is independent; send its messages as history for the next turn.
thinking_level EnumControls thinking effort ('minimal' or 'high') and requests thought summaries. Omit to use the provider default ('minimal'); thinking cannot be disabled.
Possible enum values: minimal, high
include_thoughts booleanWhether to include thought summaries. Omit to preserve the existing behavior: an explicit thinking_level requests summaries. Set limit_generations=false to return summary text in description. This does not disable thinking or return intermediate thought images.
temperature floatSampling temperature. Omit to use the provider default of 1. Explicit values use a direct Google or Vertex API.
top_p floatNucleus sampling probability. Omit to use the provider default of 0.95. Explicit values use a direct Google or Vertex API.
max_output_tokens integerMaximum output tokens for the generation. Omit to retain the provider default. Explicit values use a direct Google or Vertex API.
num_images integerThe number of images to generate. Default value: 1
seed integerThe seed for the random number generator.
aspect_ratio EnumThe aspect ratio of the generated image. Supports extreme ratios: 4:1, 1:4, 8:1, 1:8. Use "auto" to let the model decide based on the prompt. Default value: auto
Possible enum values: auto, 21:9, 16:9, 3:2, 4:3, 5:4, 1:1, 4:5, 3:4, 2:3, 9:16, 4:1, 1:4, 8:1, 1:8
output_format OutputFormatEnumThe format of the generated image. Default value: "png"
Possible enum values: jpeg, png, webp
safety_tolerance SafetyToleranceEnumThe safety tolerance level for content moderation. 1 is the most strict (blocks most content), 6 is the least strict. Default value: "4"
Possible enum values: 1, 2, 3, 4, 5, 6
Note: This property is only available through API calls.
sync_mode booleanIf True, the media will be returned as a data URI and the output data won't be available in the request history.
system_prompt stringOptional system instruction that steers the model's persona and output style across the request. Leave blank to omit; when provided, it is sent as the system instruction to Gemini (or as a system message on OpenAI-compatible providers). Default value: ""
resolution ResolutionEnumThe resolution of the image to generate. Default value: "1K"
Possible enum values: 0.5K, 1K, 2K, 4K
limit_generations booleanExperimental parameter to limit the number of generations from each round of prompting to 1. Set to True to to disregard any instructions in the prompt regarding the number of images to generate and ignore any intermediate images generated by the model. This may affect generation quality. Default value: true
enable_web_search booleanEnable web search for the image generation task. This will allow the model to use the latest information from the web to generate the image.
enable_image_search booleanGround image generation with Google Image Search. Can be combined with enable_web_search; source attribution is returned in grounding_metadata. Uses direct Google or Vertex APIs.
{
"prompt": "An action shot of a black lab swimming in an inground suburban swimming pool. The camera is placed meticulously on the water line, dividing the image in half, revealing both the dogs head above water holding a tennis ball in it's mouth, and it's paws paddling underwater.",
"history": [
{
"role": "user",
"parts": [
{
"type": "",
"text": ""
}
]
}
],
"context": [
{
"type": "",
"text": ""
}
],
"num_images": 1,
"aspect_ratio": "auto",
"output_format": "png",
"safety_tolerance": "4",
"resolution": "1K",
"limit_generations": true
}The generated images.
description string* requiredThe description of the generated images.
Reusable per-generation conversations, populated only when return_history is true. Retain every part and thought signature when continuing a conversation.
Provider grounding metadata for the generated images, including search queries, source pages and image-source attribution when available.
{
"images": [
{
"url": "https://storage.googleapis.com/falserverless/example_outputs/nano-banana-2-t2i-output.png",
"content_type": "image/png",
"file_name": "nano-banana-2-t2i-output.png"
}
],
"description": "",
"conversations": [
{
"messages": [
{
"role": "user",
"parts": [
{
"type": "",
"text": ""
}
]
}
]
}
]
}role RoleEnum* requiredNative Gemini conversation role.
Possible enum values: user, model
parts list<GeminiTextPart | GeminiImagePart | GeminiDocumentPart | GeminiVideoPart | GeminiSignaturePart | GeminiAudioPart>* requiredOrdered text, image, document, video, audio, and signature parts.
thought booleanProvider thought marker, preserved when replaying a returned conversation.
thought_signature stringOpaque provider-issued thought signature. Replay it unchanged on its original part.
type string* requiredThe text part discriminator.
text string* requiredText at this position in the conversation.
thought booleanProvider thought marker, preserved when replaying a returned conversation.
thought_signature stringOpaque provider-issued thought signature. Replay it unchanged on its original part.
type string* requiredThe image part discriminator.
image_url string* requiredOriginal image URL or data URI. Replayed without resizing or re-encoding.
thought booleanProvider thought marker, preserved when replaying a returned conversation.
thought_signature stringOpaque provider-issued thought signature. Replay it unchanged on its original part.
type string* requiredThe document part discriminator.
file_url string* requiredPDF or UTF-8 plain-text document URL or data URI (up to 15 MB).
mime_type MimeTypeEnum* requiredThe document's media type.
Possible enum values: application/pdf, text/plain
thought booleanProvider thought marker, preserved when replaying a returned conversation.
thought_signature stringOpaque provider-issued thought signature. Replay it unchanged on its original part.
type string* requiredThe video part discriminator.
video_url string* requiredVideo URL or data URI (up to 15 MB and 120 seconds), or a YouTube URL. Supported by Flash Image only.
thought booleanProvider thought marker, preserved when replaying a returned conversation.
thought_signature string* requiredProvider-issued signature-only part, replayed unchanged.
type string* requiredThe signature part discriminator.
One complete provider conversation. Pass messages as history in the next request, retaining every signature and part.
url string* requiredThe URL where the file can be downloaded from.
content_type stringThe mime type of the file.
file_name stringThe name of the file. It will be auto-generated if not provided.
file_size integerThe size of the file in bytes.
width integerThe width of the image
height integerThe height of the image
thought booleanProvider thought marker, preserved when replaying a returned conversation.
thought_signature stringOpaque provider-issued thought signature. Replay it unchanged on its original part.
type string* requiredThe audio part discriminator.
audio_url string* requiredOriginal audio URL or data URI from a previous Flash Image request (up to 15 MB).