Ephemeral tokens provide secure, short-lived authentication for client-side applications. Use them when connecting to the Speech to Speech API from browsers or mobile apps to avoid exposing your API key.

How It Works

Your server requests an ephemeral token from xAI using your API key
Your server passes the ephemeral token to the client
The client uses the ephemeral token to authenticate the WebSocket connection
The token expires automatically after the configured duration

Creating Ephemeral Tokens

You need to set up a server endpoint to fetch the ephemeral token from xAI. The ephemeral token gives the holder scoped access to resources.

Endpoint: POST https://api.x.ai/v1/realtime/client_secrets

curl --url https://api.x.ai/v1/realtime/client_secrets \
  -H "Content-Type: application/json" \
  -H "Authorization: Bearer $XAI_API_KEY" \
  --data '{
    "expires_after": {
      "seconds": 300
    }
  }'

# Note: Does not support "session" or "expires_after.anchor" fields

# Example ephemeral token endpoint with FastAPI

import os
import httpx
from fastapi import FastAPI

app = FastAPI()
SESSION_REQUEST_URL = "https://api.x.ai/v1/realtime/client_secrets"
XAI_API_KEY = os.getenv("XAI_API_KEY")

@app.post("/session")
async def get_ephemeral_token():
    # Send request to xAI endpoint to retrieve the ephemeral token
    async with httpx.AsyncClient() as client:
        response = await client.post(
            url=SESSION_REQUEST_URL,
            headers={
                "Authorization": f"Bearer {XAI_API_KEY}",
                "Content-Type": "application/json",
            },
            json={"expires_after": {"seconds": 300}},
        )

    # Return the response body from xAI with ephemeral token
    return response.json()

// Example ephemeral token endpoint with Express

import express from 'express';

const app = express();
const SESSION_REQUEST_URL = "https://api.x.ai/v1/realtime/client_secrets";

app.use(express.json());

app.post("/session", async (req, res) => {
  const r = await fetch(SESSION_REQUEST_URL, {
    method: "POST",
    headers: {
      Authorization: \`Bearer \${process.env.XAI_API_KEY}\`,
      "Content-Type": "application/json",
    },
    body: JSON.stringify({
      expires_after: { seconds: 300 }
    }),
  });

  const data = await r.json();
  res.json(data);
});

app.listen(8081);

Using Ephemeral Tokens

The ephemeral token can be used in the same fashion as an API key:

import os
import websockets

base_url = "wss://api.x.ai/v1/realtime?model=grok-voice-latest"

# Connect with API key in Authorization header
async with websockets.connect(
    uri=base_url,
    ssl=True,
    additional_headers={"Authorization": f"Bearer {OBTAINED_EPHEMERAL_TOKEN}"}
) as websocket:
    # WebSocket connection is now authenticated
    pass

import WebSocket from "ws";

const baseUrl = "wss://api.x.ai/v1/realtime?model=grok-voice-latest";

// Connect with API key in Authorization header
const ws = new WebSocket(baseUrl, {
  headers: {
    Authorization: "Bearer " + OBTAINED_EPHEMERAL_TOKEN,
    "Content-Type": "application/json",
  },
});

ws.on("open", () => {
  console.log("Connected with ephemeral token authentication");
});

Browser WebSocket Authentication

If you need to send the ephemeral token from the browser, you can add the ephemeral token with a prefix xai-client-secret. to the sec-websocket-protocol header:

new WebSocket("wss://api.x.ai/v1/realtime", [\`xai-client-secret.\${OBTAINED_EPHEMERAL_TOKEN}\`]);

Last updated:July 21, 2026