Meta Tech ProviderComparison
ThinnestAI vs Cartesia
Cartesia makes the fastest English TTS in the world. ThinnestAI is a full voice agent platform — and Cartesia is one of the TTS providers we support.
TL;DR
- Cartesia is fundamentally a TTS company with a thin agent SDK. ThinnestAI is a full voice agent platform that includes Cartesia as one of its curated TTS providers.
- Cartesia Sonic supports 42 languages including Hindi, but Indic coverage beyond Hindi is thin. ThinnestAI replies in 37 languages, including all 22 scheduled Indian languages in native script, routed across the best provider per language.
- If you want fast English TTS and are building everything else yourself, Cartesia is excellent. If you want a complete voice platform for India and global teams, ThinnestAI is the fit.
ThinnestAI vs Cartesia6 rows
Product scope
Indian language coverage
Phone / SIP out of the box
English TTS speed / quality
Pricing
Pricing note
Cartesia uses credit-based pricing (15 credits/sec for Sonic TTS). Line voice agents are $0.05 per creation plus provider pass-through. It is a TTS-first product — a full voice agent stack built on Cartesia still requires you to add STT, LLM routing, agent configuration, phone procurement and billing. ThinnestAI gives you all of that with Cartesia included as one of the curated TTS options, at a flat, all-inclusive rate — ₹2/min on standard voices and ₹2.5/min on premium voices, telephony in the price either way, metered in 30-second pulses.
Features
Feature-by-feature comparison
| Feature | ThinnestAI | Cartesia |
|---|---|---|
| Product scope | Full platform (STT + LLM + TTS + phone + channels + billing) | TTS + thin agent SDK |
| Indian language coverage | All 22 scheduled Indian languages via provider routing | Hindi included in 42-language model; other Indic is thin |
| Phone / SIP out of the box | Native (buy from us, or import a Plivo, Vobiz, Twilio or Telnyx number via BYOK) | Not included — wire up Twilio + LiveKit yourself |
| English TTS speed / quality | Cartesia is available as a curated option | Sonic-3 — ~90ms TTFA, industry-leading |
| Voice cloning | Not offered — curated voice library (standard and premium) | Best-in-class voice cloning |
| INR billing / GST | Yes | No — USD credits |
Honest fit
When each one wins
Choose CartesiaTheir call
You are building a product where TTS latency is the primary constraint.
You need premium English voice cloning (IVC / PVC).
You are building your own agent stack and only need a best-in-class TTS API.
Choose Cartesia when
You need the fastest English TTS
- You are building a product where TTS latency is the primary constraint.
- You need premium English voice cloning (IVC / PVC).
- You are building your own agent stack and only need a best-in-class TTS API.
- You are fine building everything else — STT, LLM routing, phone, agent configuration — yourself.
Choose ThinnestAIOur call
You want STT, LLM, TTS, phone, agent settings and billing in one managed platform.
You want all 22 scheduled Indian languages in native script — 37 reply languages in total — supported via opinionated provider routing.
You want INR billing and GST invoices.
Choose ThinnestAI when
You need a complete voice platform for India and the world
- You want STT, LLM, TTS, phone, agent settings and billing in one managed platform.
- You want all 22 scheduled Indian languages in native script — 37 reply languages in total — supported via opinionated provider routing.
- You want INR billing and GST invoices.
- You can still use Cartesia as your TTS provider inside ThinnestAI — it's part of our curated stack, not a competitor.
Keep exploring
Also compared with
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FAQ
Frequently asked questions
Is ThinnestAI a competitor to Cartesia?
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No. Cartesia is a TTS provider. ThinnestAI is a voice agent platform that treats Cartesia as one of several curated TTS options. You can build an agent in ThinnestAI that uses Cartesia Sonic for English and a different provider for Indian languages.
Does Cartesia Sonic support Hindi?
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Yes — Hindi is included in the 42-language Sonic model. Quality is decent but not Indic-tuned. For production Hindi / Marathi / Tamil / Telugu deployments ThinnestAI routes to providers that specialize in those languages, which is usually a better fit.
Can I use Cartesia inside ThinnestAI?
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Yes. Cartesia Sonic is one of ThinnestAI's curated TTS options — pick it for any agent with no extra setup, all inside the flat rate, from ₹2/min.
When is Cartesia the right primary choice?
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If you're an engineering team building your own voice stack and only need the fastest, most expressive English TTS API available. For anything beyond TTS (agent configuration, phone, multi-provider routing, India ops) you'd be building it yourself.