Cartesia (Line) pricing & cost
Developers wanting ultra-low-latency TTS (Sonic) embedded in custom agents.
Entry price
Free; Pro $5/mo; Startup $49/mo
AI usage rate
$0.06/min (Line) + $0.014/min telephony
Free tier
Yes — 20k credits/mo
Billing model
per-minute
Our verdict
A strong low-latency voice layer for builders — but the $0.06/min Line figure is before LLM and STT, so model the full stack.
Strengths
- Ultra-low-latency Sonic TTS
- Cheap per-minute Line layer
- Generous credit free tier
Watch-outs
- Character-based billing makes per-minute fuzzy
- $0.06/min excludes LLM + STT
- Cloning has training fees
Who it's for
Developers wanting ultra-low-latency TTS (Sonic) embedded in custom agents. Typically a fit for small, mid teams.
Sources
Cartesia (Line) alternatives
Free ($0.14/min); Build $299/mo ($0.12/min); Scale $499/mo ($0.11/min)
The 'no surprises' option — its headline rate is roughly the real rate, which is rare; you pay a monthly fee for that predictability.
Deepgram (Voice Agent API)$0 PAYG ($200 free credit)
The cost-sensitive, high-volume builder's pick — best free credit in the category, but mind the websocket-time billing.
Dialpad (AI Agents)Phone from $15/user/mo; AI Agents = contact sales
Buy it for the phone system with AI baked in — the autonomous voice-agent product, though, is a contact-sales black box.
ElevenLabs (Agents)Free (15 agent min/mo); Creator $22/mo
Pick it when voice quality is the priority — just remember the bundled minutes don't include the LLM passthrough, and dead air bills.