Grok Voice Think Fast 2.0

Realtime speech-to-speech model for voice agents, driven over a WebSocket at wss://api.x.ai/v1/realtime with low-latency turn-taking and server-side tool use. Billed by connected audio time and by session concurrency rather than by token, so the token price fields are null by design. Released 2026-07-29, dated by xAI's own release notes ('grok-voice-think-fast-2.0 is now available with Speech to Speech'), and the alias grok-voice-latest was stated in the same entry to route here from 2026-08-05 - so an application pinned to that alias moved to this model on that date without changing a string. THE PUBLISHED RATE IS $0.08 per minute of audio, which xAI itself also prints as $4.80/hr, and the models-index hydration payload agrees: 'realtimeAudioSecondPrice': '13333333' in the 1e-10 USD units this catalog calibrated against rows it already held, which is $0.0013333 per second. The payload additionally carries 'pstnMinutePrice': '100000000' - $0.01 per minute, the same integer this catalog already publishes as $0.01 per image elsewhere in xAI's payload, so the unit is confirmed rather than assumed - for sessions bridged to the public telephone network. TWO FURTHER PAYLOAD FIELDS ARE DELIBERATELY NOT CARRIED, and this is a closed path rather than an oversight: 'realtimeAudioTokenPrice': '266667' and 'realtimeTextInputPrice': '40000000' cannot both be read in the per-token unit that works everywhere else in this payload - the second would come out four orders of magnitude above any published rate - and xAI's pricing page prints the second one as a bare figure of $0.004 for realtime text with no denominator at all, so neither surface establishes what either field is per. A figure whose unit is unknown is not a price, and this catalog will not publish one. Session concurrency is the rate-limit axis: 10 concurrent sessions at the base tier, 20 / 50 / 100 / 200 / 400 at tiers 1 to 5. A first-generation grok-voice-think-fast-1.0 was released 2026-04-23 and is absent from the current models payload; this catalog does NOT infer a retirement from that absence and carries no row for it. Added to the catalog 2026-09-19 as a completeness fix; xAI published nothing on this date.

Source: xAI official documentation ↗

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