Cartesia vs xAI
Cartesia rates higher than xAI's Grok TTS and runs faster.
ServiceNow, Decagon, and Quora run their production voice agents on Cartesia. One model, 44 languages, on-prem or air-gapped when you need it.
Voice quality
Cartesia rates higher than xAI's Grok TTS
- Cartesia's Sonic 3.6 ranks first of the 94 models on Artificial Analysis's Provider Voice Arena.
- xAI's Grok TTS rates well below it.
Provider Voice Arena Elo
Higher is better
Latency
Cartesia is faster across the whole distribution
- Both models measured by Coval, an independent voice AI evaluation platform, rather than self-reported.
- Every quartile of Grok TTS's spread sits above Cartesia's, and the two barely overlap. This is not a gap that shows up only in the average.
Latency Variation: Distribution of TTFA values
Lower is better
Read the latency measurements
Time to first audio in milliseconds. The box spans the middle 50% of requests; the line marks the median. Whiskers are not absolute minimums or maximums.
- Sonic 3.5: median 268ms; middle 50% 234–298ms; whiskers 139–394ms.
- Grok TTS: median 428ms; middle 50% 393–468ms; whiskers 322–582ms.
Reasons why companies choose Cartesia over xAI
Human-like naturalness
Intonation, pacing, pronunciation, emotion, and audio quality that drive higher completion rates
Cartesia1282 EloxAI1113 EloAugust 2026
Latency (P95)
Decides whether it feels like a conversation or a phone tree.
Cartesia367msSonic 3.5xAI536msAugust 2026
Languages
Comprehension and trust across a global customer base.
Cartesia44 languages from one model, with accents calibrated per regionxAI20+ languagesVoice range
How far the catalogue stretches before you need your own voice.
CartesiaA full voice library, plus 10-second instant clones and 30-minute professional clonesxAIBuilt-in voices, plus cloning from a reference clipEnd-to-end stack
How many vendors it takes to run one call.
CartesiaTTS, STT, and Agents from one vendor, on one API. The only provider ranked first on both speech and transcriptionxAIText to speech, transcription, and speech-to-speech
Frequently asked questions
Is SpaceXAI the same as xAI and Grok?
Yes. xAI merged into SpaceX in May 2026 and the combined company is SpaceXAI, so the same team is referred to by both names. Its text-to-speech model ships as Grok TTS, which is the name this page uses. Artificial Analysis lists that model as SpaceXAI TTS, so the score here is the one on their board even though the label reads differently.
How is the quality score measured?
It comes from Artificial Analysis, an independent benchmark. Listeners hear two clips of the same line without being told which model produced either, and pick the one they prefer. The Provider Voice Arena lets every model speak in its own voices, so a voice roster counts alongside the model that speaks it. Sonic 3.6 ranks first of the 94 models rated there, and first on their Controlled Voice Arena, which gives every model the same set of cloned voices.
Can I run Cartesia on my own infrastructure?
Yes. Cartesia deploys on-prem and air-gapped, which teams in healthcare, finance, and government use to keep audio inside their own network, backed by a 99.9% uptime SLA.
How many languages does Cartesia support?
44 languages from one model, including English, Spanish, French, German, and Japanese. Accents are calibrated per region rather than bolted onto an English model, so Spanish for Mexico City and Spanish for Madrid are not the same voice.
How long does it take to switch from xAI?
One to two weeks for most teams. Cartesia is integrated into the major voice agent platforms and every model is on the public API, so there is no platform to move onto and nothing to unpick later.
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