Cartesia Sonic
last releaseMay 4, 2026
powered bySonic 3.5
goblin vibe check:
the pick if your npc talks back and waiting half a second would kill the illusion
purpose-built for real-time conversational ai. sub-100ms tts — fastest available tts api. not as expressive as elevenlabs but unmatched latency. heavy adoption in voice agent and chatbot stacks where latency is the primary constraint.
speed
90ms
streams first byte of audio in about 90ms42-language support on the latest stable snapshotnatural readout for phone numbers, ids, emails, and codesvoice cloning and highly expressive conversational speech
key features
streams first byte of audio in about 90ms42-language support on the latest stable snapshotnatural readout for phone numbers, ids, emails, and codesvoice cloning and highly expressive conversational speech
spec & usage
stable snapshot sonic-3.5-2026-05-04 is the current production pin
use sonic-3.5 for stable releases or sonic-latest for beta updates
built for low-latency tts in voice agents, dubbing, and narration
scope:
audiovoiceapicloudpaidreal-timefast
launchMay 31, 2024
last releaseMay 4, 2026