Voice Overview

Build real-time, speech-to-speech voice agents over WebSockets, with low-latency turn-taking and tool use. For client-side apps, use Ephemeral Tokens to connect securely without exposing your API key.

View docs

import asyncio
import json
import os
import websockets

async def voice_agent():
    async with websockets.connect(
        "wss://api.x.ai/v1/realtime?model=grok-voice-think-fast-1.0",
        additional_headers={"Authorization": f"Bearer {os.environ['XAI_API_KEY']}"}
    ) as ws:
        # Configure voice and enable tools
        await ws.send(json.dumps({
            "type": "session.update",
            "session": {
                "voice": "eve",
                "instructions": "You are a helpful customer support agent.",
                "turn_detection": {"type": "server_vad"},
                "tools": [{"type": "web_search"}]
            }
        }))
        
        # Stream audio and receive responses
        async for message in ws:
            event = json.loads(message)
            if event["type"] == "response.output_audio.delta":
                # Play audio: base64.b64decode(event["delta"])
                pass

asyncio.run(voice_agent())

import WebSocket from "ws";

const ws = new WebSocket("wss://api.x.ai/v1/realtime?model=grok-voice-think-fast-1.0", {
  headers: { Authorization: `Bearer ${process.env.XAI_API_KEY}` },
});

ws.on("open", () => {
  // Configure voice and enable tools
  ws.send(JSON.stringify({
    type: "session.update",
    session: {
      voice: "eve",
      instructions: "You are a helpful customer support agent.",
      turn_detection: { type: "server_vad" },
      tools: [{ type: "web_search" }]
    }
  }));
});

ws.on("message", (data) => {
  const event = JSON.parse(data);
  if (event.type === "response.output_audio.delta") {
    // Play audio: Buffer.from(event.delta, "base64")
  }
});

Demo Apps: Web Agent · Twilio Phone Agent · WebRTC Agent · iOS Tester App

Text to Speech

Convert text to spoken audio in 5 expressive voices. Inline speech tags (laughter, whispers, pauses) and output formats from high-fidelity MP3 to telephony μ-law. Unary requests or WebSocket streaming.

View docs

curl -X POST https://api.x.ai/v1/tts \
  -H "Authorization: Bearer $XAI_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "text": "Welcome to xAI. How can I help you today?",
    "voice_id": "eve",
    "language": "en"
  }' \
  --output welcome.mp3

import os
import requests

response = requests.post(
    "https://api.x.ai/v1/tts",
    headers={
        "Authorization": f"Bearer {os.environ['XAI_API_KEY']}",
        "Content-Type": "application/json",
    },
    json={
        "text": "Welcome to xAI. How can I help you today?",
        "voice_id": "eve",
        "language": "en",
    },
)

with open("welcome.mp3", "wb") as f:
    f.write(response.content)

import fs from "fs";

const response = await fetch("https://api.x.ai/v1/tts", {
  method: "POST",
  headers: {
    Authorization: `Bearer ${process.env.XAI_API_KEY}`,
    "Content-Type": "application/json",
  },
  body: JSON.stringify({
    text: "Welcome to xAI. How can I help you today?",
    voice_id: "eve",
    language: "en",
  }),
});

const buffer = Buffer.from(await response.arrayBuffer());
fs.writeFileSync("welcome.mp3", buffer);

Real World Examples: LiveKit · Pipecat

Speech to Text

Transcribe audio files in a single call or stream over WebSocket. 12 audio formats, word-level timestamps, multichannel, speaker diarization, and 25 languages.

View docs

curl -X POST https://api.x.ai/v1/stt \
  -H "Authorization: Bearer $XAI_API_KEY" \
  -F file=@recording.mp3

import os
import requests

response = requests.post(
    "https://api.x.ai/v1/stt",
    headers={"Authorization": f"Bearer {os.environ['XAI_API_KEY']}"},
    files={"file": ("recording.mp3", open("recording.mp3", "rb"), "audio/mpeg")},
)

print(response.json()["text"])

import fs from "fs";

const formData = new FormData();
formData.append("file", new Blob([fs.readFileSync("recording.mp3")]), "recording.mp3");

const response = await fetch("https://api.x.ai/v1/stt", {
  method: "POST",
  headers: { Authorization: `Bearer ${process.env.XAI_API_KEY}` },
  body: formData,
});

const result = await response.json();
console.log(result.text);

Real World Examples: Voximplant

Quick Start: Custom Voices

Clone a voice from a short reference clip, then use the resulting voice_id anywhere a built-in voice works:

# 1. Create a custom voice from a reference audio clip (max 120s).
curl -X POST https://api.x.ai/v1/custom-voices \
  -H "Authorization: Bearer $XAI_API_KEY" \
  -F "name=Friendly Narrator" \
  -F "language=en" \
  -F "file=@reference.wav;type=audio/wav"

# Response: { "voice_id": "nlbqfwie", ... }

# 2. Use the custom voice for TTS.
curl -X POST https://api.x.ai/v1/tts \
  -H "Authorization: Bearer $XAI_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "text": "Hello! This is my custom voice.",
    "voice_id": "nlbqfwie",
    "language": "en"
  }' \
  --output custom.mp3

import os
import requests

# 1. Create a custom voice from a reference audio clip (max 120s).
with open("reference.wav", "rb") as f:
    create = requests.post(
        "https://api.x.ai/v1/custom-voices",
        headers={"Authorization": f"Bearer {os.environ['XAI_API_KEY']}"},
        files={"file": ("reference.wav", f, "audio/wav")},
        data={"name": "Friendly Narrator", "language": "en"},
    )
voice_id = create.json()["voice_id"]

# 2. Use the custom voice for TTS.
speech = requests.post(
    "https://api.x.ai/v1/tts",
    headers={
        "Authorization": f"Bearer {os.environ['XAI_API_KEY']}",
        "Content-Type": "application/json",
    },
    json={
        "text": "Hello! This is my custom voice.",
        "voice_id": voice_id,
        "language": "en",
    },
)
with open("custom.mp3", "wb") as f:
    f.write(speech.content)

import fs from "fs";

// 1. Create a custom voice from a reference audio clip (max 120s).
const form = new FormData();
form.append("file", new Blob([fs.readFileSync("reference.wav")]), "reference.wav");
form.append("name", "Friendly Narrator");
form.append("language", "en");

const create = await fetch("https://api.x.ai/v1/custom-voices", {
  method: "POST",
  headers: { Authorization: `Bearer ${process.env.XAI_API_KEY}` },
  body: form,
});
const { voice_id } = await create.json();

// 2. Use the custom voice for TTS.
const speech = await fetch("https://api.x.ai/v1/tts", {
  method: "POST",
  headers: {
    Authorization: `Bearer ${process.env.XAI_API_KEY}`,
    "Content-Type": "application/json",
  },
  body: JSON.stringify({
    text: "Hello! This is my custom voice.",
    voice_id,
    language: "en",
  }),
});
fs.writeFileSync("custom.mp3", Buffer.from(await speech.arrayBuffer()));

The custom voice_id also works with the streaming TTS WebSocket and the Voice Agent realtime API. See the Custom Voices guide for the full API.

Voices

When using the Voice Agent API or Text to Speech, you can choose between 5 distinct voices. Each has its own personality and tone, so pick the one that best fits your application — from upbeat and conversational to authoritative and instructional.

Voice	Type	Tone	Description
`eve`	Female	Energetic, upbeat	Default voice, engaging and enthusiastic
`ara`	Female	Warm, friendly	Balanced and conversational
`rex`	Male	Confident, clear	Professional and articulate, ideal for business
`sal`	Neutral	Smooth, balanced	Versatile voice suitable for various contexts
`leo`	Male	Authoritative, strong	Decisive and commanding, suitable for instructional content

Enterprise Compliance & Security

The xAI Voice APIs are built for production workloads with strict security and compliance requirements. All audio data is processed in real time and never stored or used for training.

✓

SOC 2 Type II

Audited controls for security, availability, and confidentiality

✓

HIPAA Eligible

BAA available for healthcare applications handling PHI

✓

GDPR Compliant

Data processing agreements and EU data residency options

✓

Data Residency

Regional processing for compliance requirements

✓

High Availability

Multi-region infrastructure with custom SLAs for enterprise workloads

✓

SSO & RBAC

SAML SSO, role-based access, and audit logging

Last updated: April 26, 2026