Cartesia
Lowest LatencySonic — 40ms model latency for genuinely real-time voice agents.
Cartesia's 'Sonic' models have redefined the latency standard. Using a State Space Model (SSM) architecture instead of a transformer, Cartesia achieves a 40ms model latency (~135ms end-to-end). For interactive voice agents — where every 100ms of latency degrades conversational naturalness — Cartesia is the only viable choice. It's the right pick for real-time customer-service bots, live conversation co-pilots, and any voice surface where latency matters more than the absolute peak of audio quality.
Models
Sonic
Latest40ms model latency, ~135ms end-to-end
Input Price
Subscription + credits
Input Types
Text
Output Types
Audio (real-time)
Sonic Multi
Multilingual variant for global voice agents
Input Types
Text (multilingual)
Output Types
Audio
Use Cases
Real-Time Voice Agents
Customer-service bots and conversation co-pilots where conversational latency is the primary quality metric.
Live Conversation Tooling
Real-time transcription co-pilots, sales call assistants, meeting agents that respond in-flight.
Interactive Voice Surfaces
Any product surface where the user is talking and waiting for a response — Sonic is the only model that feels human.
Voice-First UX
Apps where voice is the primary interface and user perception of quality is dominated by responsiveness.
Why use Cartesia on Nagent?
Nagent adds enterprise orchestration, observability, and workflow automation on top of Cartesia's raw model capabilities.
Default routing target for voice agents that need genuine real-time responsiveness
Combine with Anthropic / OpenAI brains in our voice-agent skill — Cartesia handles speech, the LLM handles reasoning
Automatic failover to ElevenLabs Flash for non-time-critical responses
KARMIC scoring tracks user-perceived latency and routes accordingly
How to access Cartesia on Nagent
Open Agent Studio
Navigate to Agent Studio in your Nagent workspace.
Select Cartesia
Pick Sonic for English real-time agents or Sonic Multi for multilingual deployments.
Wire to a Reasoning Model
Pair Sonic with an LLM (Anthropic / OpenAI / Grok) for the brain behind your voice agent.
Common questions about Cartesia
Real buyer and developer questions, answered. Click any item to expand.
Why is the latency so much better than competitors?
Cartesia uses State Space Model (SSM) architecture instead of transformers. The math is fundamentally faster for streaming audio generation — that's where the 40ms model latency comes from.
Is the audio quality as good as ElevenLabs?
Close, not equal. ElevenLabs still wins on emotional range and naturalism for long-form work. For real-time conversation, the latency benefit dominates the small remaining quality gap — users perceive responsiveness as quality.
Can I use my own voice with Cartesia?
Yes via voice cloning, with a simpler workflow than ElevenLabs PVC — just a few minutes of source audio. Quality is good for conversational use; for long-form narration, ElevenLabs PVC is still the better choice.
Does Cartesia drop into my existing voice agent stack?
Yes — drop-in replacement for ElevenLabs in our voice-agent skill. Pair it with any LLM brain (Claude, GPT-5, Grok) for the reasoning side. The agent definition doesn't change; just swap the speech provider.
Ready to use Cartesia inside your agents?
Get started in minutes — no API key management required.