Grok Voice Think Fast 2.0
Released 2026-07-29; grok-voice-latest switched to it on 2026-08-05. Predecessor grok-voice-think-fast-1.0 can still be pinned. 20+ languages; audio PCM (8-48 kHz), Opus 24 kHz, G.711 mu-law/A-law; server VAD, session resumption (30 min), custom cloned voices. xAI says Starlink A/B tests raised sales conversion and support containment. Benchmarks are xAI-reported.
- Input
- audio, text
- Output
- audio, text
- License
- proprietary
- Pricing
- per minute: $0.08 (USD per minute of audio ($4.80/hr), plus $0.004 per text input (as listed on the xAI pricing page)) source
- Verified
- 2026-09-29
How to call it
| Provider | Model id | Endpoint / URL | Docs |
|---|---|---|---|
| xAI API (Voice Agent / speech-to-speech, WebSocket) | grok-voice-think-fast-2.0 | wss://api.x.ai/v1/realtime?model=grok-voice-think-fast-2.0 | docs |
| xAI API (alias) | grok-voice-latest | — | docs |
| Web app | — | grok.com | — |
Notable capabilities (4)
- Reasoning while speaking: Speech-to-speech model that reasons in real time (reasoning effort 'high' by default, can be set to 'none'); 97.2% Big Bench Audio, 82.9 on the Artificial Analysis Speech-to-Speech Quality Index (vs 75.7 for v1.0). source
- Faster first audio: Time to first audio cut from 1.25 s (v1.0) to 0.70 s; Full Duplex Bench 95.1%, tau-voice Bench 56.5% (xAI-reported). source
- Built-in server-side tools: Web search, X search, collections (file) search and remote MCP callable from inside a voice session, plus custom functions. source
- OpenAI Realtime-compatible protocol: Largely compatible with the OpenAI Realtime SDK: change base URL to https://api.x.ai/v1 and the API key (minor event-name differences). source
xAI's realtime voice-agent model (also used in the Grok app, Tesla vehicles and Starlink support).
# OpenAI Realtime-compatible WebSocket
import websockets, os
url = "wss://api.x.ai/v1/realtime?model=grok-voice-think-fast-2.0"
ws = await websockets.connect(url, additional_headers={"Authorization": f"Bearer {os.environ['XAI_API_KEY']}"})
Sources: https://x.ai/news/grok-voice-think-fast-2 · https://docs.x.ai/developers/model-capabilities/audio/voice-agent · https://docs.x.ai/developers/pricing
Timeline entry
- xAI releases Grok Voice Think Fast 2.0 speech-to-speech model for voice agents ★★★
On 2026-07-29 xAI (SpaceXAI) released Grok Voice Think Fast 2.0, a reasoning speech-to-speech model for its OpenAI-Realtime-compatible Voice Agent API at $0.08/min, scoring 82.9 on the Artificial Analysis Speech-to-Speech Quality Index and cutting time to first audio to 0.70 s.
Other xAI models
Grok 4.7 · Grok Voice Transcribe 2.0 · Grok Imagine Image 2.0 · Grok Imagine Video 1.5 · Grok Build 0.1 · Grok Text to Speech (Grok TTS API) · Grok 4.3 · Grok 4.20 (Reasoning / Non-reasoning / Multi-Agent)