How to use Cartesia
Create an account and call the Sonic model through the API, or test it in the playground, with your text and a chosen voice. It is billed per character, so estimate cost from your output volume. It suits being embedded in a voice-agent stack rather than one-off content.
Best for
Low-latency, real-time speech for conversational voice agents. Streaming synthesis where response time is critical. Developer and API-first voice infrastructure.
How it behaves
Character-based billing where one credit equals one character of output. The flagship Sonic model is tuned for ultra-low latency, and the free tier is personal and non-commercial.
Tips
Estimate cost from output character count. Use it inside a live agent stack, not for one-off narration. Prototype in the playground before wiring the API.
Pricing
Free tier with a monthly allowance for non-commercial use. Paid tiers scale up to a few hundred dollars a month, working out to roughly $5 to $37 per million characters.