#1, then #1 again.
Introducing Sonic-3.5 and Ink-2.
Build your entire voice stack with one model provider - the only one ranked #1 on both speech and transcription. Don't compromise on quality or speed.
The full stack for interactive intelligence.
Co-designed end to end for voice agents
The only STT and TTS optimized across the full real-time pipeline.
One API, no assembly required
Ship both models in one integration — less vendor stitching, more building.
The tightest loop in voice
Hit sub-90ms TTS and 100ms transcript latency with native turn detection.
Join the teams making the switch to Cartesia
Cartesia Sonic 3.5 has become one of the top-performing models for us by combining low latency with natural pacing… helping us deliver strong voice quality across a growing set of languages where other models often fall short.
Lydia Zarcone, Voice Product Manager
At Cartesia, we believe the tradeoffs that define today’s voice AI
Speed versus Naturalness,
Accuracy versus Cost,
are largely architectural in origin, not inevitable.
We’ve spent years building and scaling State Space Models because we believe the right primitives eliminate constraints rather than work around them.
And we built Sonic-3.5 and Ink-2 not by optimizing within accepted limits, but by questioning whether those limits need to exist at all.
Build with the fastest models you can trust.
Our models are designed for live, synchronous interactions, built on State Space Models (SSMs). A new primitive for large-scale foundation models, SSMs deliver ultra-low latency, long-context reasoning, and greater efficiency at scale.
Trusted by leading enterprises. Speaking from experience.
Discover success stories
“Cartesia Sonic 3.5 has become one of the top-performing models for us by combining low latency with natural pacing… helping us deliver strong voice quality across a growing set of languages where other models often fall short.”
Lydia Zarcone
Voice Product Manager
“We didn’t switch to Sonic 3.5 because it was incrementally better, we switched because nothing else came close… we’ve seen a 2.9% lift in our conversion and a 12.2% increase in customer engagement.”
Akshay Ramaswamy
Staff Product Manager
Capabilities