Cartesia

Cartesia

Ultra-low-latency real-time text-to-speech powered by the Sonic model, built for live voice AI agents

Freemium
AI Voice Generators
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About Cartesia

Cartesia is a voice AI platform whose Sonic text-to-speech model is engineered for real-time, conversational latency. Built on state space model architecture, Sonic delivers time-to-first-audio as low as around 40ms and sub-100ms model latency, so voice agents can respond without awkward pauses. It supports 40-plus languages, instant voice cloning from a short audio sample, custom pronunciations, and a streaming API. Cartesia also offers speech-to-text and an agent layer, plus cloud, on-premises, and on-device deployment.
Learn more at Cartesia

Key Features

  • Sonic model with sub-100ms latency and roughly 40ms time-to-first-audio
  • Real-time streaming text-to-speech API for live voice agents
  • Instant voice cloning from a short audio sample
  • Support for 40-plus languages with localization across voices
  • Custom pronunciations for names, codes, and domain terms
  • Cloud, on-premises, and on-device deployment with HIPAA, PCI, and SOC 2 options

Pros & Cons

What we like

  • Among the lowest-latency TTS engines available, well suited to live conversation
  • Natural, expressive output that handles alphanumerics and jargon cleanly
  • Flexible deployment including on-prem and on-device for compliance-heavy use
  • Free tier lets developers test the API before committing

Room for improvement

  • Free tier blocks commercial use, voice cloning, and localization
  • Character-based credit pricing can get expensive at high volume
  • Focused on voice, so it is not a general-purpose creative audio suite
  • Premium Pro voice cloning costs more per character plus a training fee

Frequently Asked Questions

What is Cartesia?
Cartesia is an AI voice platform built around its Sonic models for ultra-low-latency, real-time text to speech. Designed for developers building voice agents, it delivers natural multilingual speech across 40+ languages with time-to-first-audio in the tens of milliseconds, plus instant voice cloning from a short clip.
How much does Cartesia cost?
Cartesia uses usage-based pricing where you pay for credits and agent minutes, with unlimited workspace seats on every plan. A Pro plan runs only a few dollars a month, around 4 to 5 dollars, and Enterprise pricing with custom models and SLAs is quoted by their sales team for higher volume needs.
What is Cartesia best for?
Cartesia is best for developers building real-time conversational voice agents, phone bots, and live assistants where latency directly affects how natural the interaction feels. Its Sonic models target sub-100ms response, so it suits production voice apps far more than one-off narration or marketing voiceover work.
Why is Cartesia known for low latency?
Cartesia's Sonic models are built on state space model architecture tuned for live, synchronous speech, reaching time-to-first-audio around 90ms and as low as roughly 40ms on the Turbo model. That speed is what makes back-and-forth voice agents feel responsive instead of laggy, which is Cartesia's core focus.

Best For

Real-time voice agents for support, healthcare, banking, and insuranceConversational IVR and phone systems that need instant responsesMultilingual narration and localized voice experiencesAdding a cloned brand voice to apps and assistants

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