xAI launched Custom Voices on May 2, 2026, allowing developers to clone a voice from 90–120 seconds of reference audio; the generated model is ready in under two minutes and integrates directly into the existing REST TTS, streaming TTS, and Voice Agent APIs at no extra cost. A two-step passphrase verification—checking that voice characteristics match in real time before accepting the reference clip—is designed to prevent cloning of third-party recordings. Console access is limited to the United States (excluding Illinois) and API access requires an Enterprise plan; a Voice Library of 80+ preinstalled voices across 28 languages ships alongside it. The feature extends xAI's Grok Voice Think Fast 1.0 infrastructure, which already handles Starlink customer service calls.