Cartesia Line

Cartesia Line is a developer platform that adds realtime audio orchestration, deployment, observability, and an agent builder around Cartesia's speech-to-text and text-to-speech models. Teams can connect any LLM, call external APIs, deploy custom code, and manage agent versions in Cartesia's runtime.

Editorial research · Reviewed Jul 10, 2026

Test it yourself

Official Cartesia developer workspace for trying models and creating API keys.

Try it yourself

Quick facts

Platform type

Voice Agent Platform

Inbound calls

Yes

Outbound calls

Yes

Human handoff

Yes

Setup difficulty

Technical

Pricing model

Usage and enterprise pricing; verify Line, speech-model, telephony, and deployment costs

Developer friendly

Yes

Pricing details

Cartesia publishes model plans but a clear all-in Line agent-minute rate was not confirmed. Request or verify current Line, speech, deployment, concurrency, and telephony pricing before procurement.

Integrations

Cartesia InkCartesia SonicCustom LLMsCustom APICLIWebhooks

Data and permissions

Voice agents may talk to customers, access records, record calls, and trigger external actions.

Can read customer data

Can write or update external systems

Can send messages

Can trigger workflows

Requires API keys

Records calls

Human approval available

Use encrypted environment variables, restrict external API tools, obtain voice and recording consent, separate deployment environments, and verify region, retention, data residency, and voice-cloning controls.