Generate the Grok voice agent's spoken reply to an uploaded audio file.
One-shot alternative to /realtime: the app connects to xAI,
configures the session (prompt / voice / tools), streams the whole
input recording, requests a single response, and returns the
agent's reply as a WAV file plus its transcript.
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("xai/grok-voice", {
input: {
audio_url: "https://v3b.fal.media/files/b/0a8dd5a2/hS140ygvRuxn-eY_qPhlv_assets_test_input_service.wav"
},
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("xai/grok-voice", {
input: {
audio_url: "https://v3b.fal.media/files/b/0a8dd5a2/hS140ygvRuxn-eY_qPhlv_assets_test_input_service.wav"
},
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("xai/grok-voice", {
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("xai/grok-voice", {
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.
audio_url string* requiredURL of the audio containing the user's speech. The Grok agent listens to it and replies with speech. Most common audio formats are supported; the audio is converted to 16-bit 24 kHz mono PCM before being sent to Grok. Maximum duration 10 minutes, maximum file size 50 MB.
prompt stringOptional system instructions describing the agent's persona and conversation context. Uses Grok's default persona when omitted.
voice EnumBuilt-in xAI voice for the agent's reply. Uses Grok's default voice when omitted.
Possible enum values: carina, zagan, helix, orion, luna, iris, altair, zenith, perseus, helios, lux, kepler, rigel, cosmo, celeste, ursa, sirius, lumen, castor, naksh, atlas, aurora, liora, ara, eve, leo, rex, sal
Server-side tools available to the agent. Web, X, and remote MCP tools are supported; every tool is disabled by default. file_search/collections are unsupported by the typed configuration due to ZDR.
{
"audio_url": "https://v3b.fal.media/files/b/0a8dd5a2/hS140ygvRuxn-eY_qPhlv_assets_test_input_service.wav",
"prompt": "You are a friendly assistant. Answer briefly and concretely."
}The Grok agent's spoken response (WAV, 24 kHz mono).
text stringTranscript of the agent's spoken response, when Grok provides one (empty string otherwise). Default value: ""
duration float* requiredDuration of the generated audio in seconds.
{
"audio": {
"url": "",
"content_type": "image/png",
"file_name": "z9RV14K95DvU.png",
"file_size": 4404019
},
"duration": 7.4
}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.
xAI-managed X search; off unless enabled is set true.
xAI-managed web search; off unless enabled is set true.
Remote MCP servers that xAI connects to and executes.
from_date stringEarliest post date, as ISO YYYY-MM-DD. Default value: "null"
enabled booleanWhether to include x_search in session.tools. Disabled by default; set true to let the agent search X posts.
enable_video_understanding booleanAllow the agent to inspect videos found on X.
enable_image_understanding booleanAllow the agent to inspect images found on X.
Exclude posts from at most 20 X handles.
Restrict results to posts from at most 20 X handles.
to_date stringLatest post date, as ISO YYYY-MM-DD. Default value: "null"
enabled booleanWhether to include web_search in session.tools. Disabled by default; set true to let the agent search the web.
enable_image_understanding booleanAllow the agent to inspect images found during web search.
Optional location used to localize search results.
Exclude results from at most five domains, without protocol or path.
Restrict results to at most five domains, without protocol or path.
server_description stringDescription of the capabilities exposed by this server. Default value: "null"
enabled booleanFalse omits this server. Default value: true
authorization stringSensitive authorization value forwarded only to xAI. Default value: "null"
Sensitive MCP request headers forwarded only to xAI.
Optional allow-list of tool names exposed from this server.
server_url string* requiredCaller-selected HTTP(S) MCP endpoint. xAI makes the remote connection and supports Streaming HTTP/SSE transports. Use at your own risk; fal does not connect to or SSRF-fetch this URL.
server_label string* requiredLabel xAI uses to identify and prefix this server's tools.
country stringCountry used to localize web-search results. Default value: "null"
city stringCity used to localize web-search results. Default value: "null"
timezone stringIANA timezone name, for example America/New_York. Default value: "null"
region stringRegion used to localize web-search results. Default value: "null"