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Cartesia

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At a glance

Price
from 5 $/mo
Vendor
Cartesia AI

Specifications & properties

Key decision factors

Pricing model
Freemium 1
Audio functions
  • Text-to-speech
  • Speech-to-text
  • Voice cloning
  • Voice changer
1
Commercial usage rights
Full commercial use 1
Latency (real-time audio)
90 ms 1

Pricing

Price from
5 $/mo 1
Free tier
Yes 1

Integration

API available
Yes 1
Streaming API
Yes 1
Report data / suggest a correction

Metrics vs. the category

Supported languages
n/a
Latency (real-time audio)
90 ms Category max 300 ms (3 with data)

Real-time voice AI platform: Sonic streaming text to speech (first audio byte in ~90ms), Ink streaming speech to text, voice changer and instant voice cloning. Credit-based plans with a free tier; Pro from $5/month.

Profile

Cartesia is a low-latency text-to-speech and voice-AI API built for developers who need real-time voice agents, not just offline narration. Its Sonic TTS model claims sub-90ms time-to-first-audio-byte, and the platform bundles speech-to-text (Ink) and a voice-agent orchestration layer (Line) alongside TTS so a full conversational pipeline can run on one stack. Pricing is credit-based with a genuine $0/month free tier and paid plans starting at $5/month, aimed at teams building phone- or app-based voice agents rather than casual narration users.

Who builds it

Cartesia was founded by Stanford AI Lab researchers Karan Goel (CEO), Albert Gu, Arjun Desai and Brandon Yang, who invented State Space Models (SSMs) — the architecture Cartesia uses instead of Transformers to get faster, more efficient speech generation. The company has raised roughly $191M total, including a $100M round with participation from NVIDIA, Kleiner Perkins, Index Ventures and Lightspeed.

Core features

  • Sonic text-to-speech model with sub-90ms claimed latency for real-time conversational use
  • Natively multilingual voice generation across 40+ languages, with instant voice cloning from about 10 seconds of reference audio
  • Cloned voices can be localized into 42 languages while preserving tone and speaker identity
  • Ink speech-to-text model for streaming transcription, including turn-detection (deciding when a user has finished speaking)
  • Line: a voice-agent platform for building and deploying phone/voice bots, billed separately at $0.06/minute for agent call time plus $0.014/minute for Cartesia-provided phone numbers
  • Deployment flexibility via cloud API, on-premise or on-device models, alongside REST API access documented at docs.cartesia.ai

Pricing

  • Free: $0/month — 20,000 credits (roughly 27 TTS minutes or ~1h51m of STT), 1 voice-agent slot, 8 concurrent calls; no commercial-use license
  • Pro: $5/month — 100,000 credits, adds a commercial-use license and instant voice cloning, 3 agent slots, 12 concurrent calls
  • Startup: $49/month — 1.25M credits, professional voice cloning and organization features, 5 agent slots, 20 concurrent calls
  • Scale: $299/month — 8M credits, priority support and higher concurrency, 10 agent slots, 60 concurrent calls
  • Enterprise: custom pricing with custom credit/concurrency limits, DPAs/BAAs, SSO and dedicated support
  • All paid tiers additionally meter voice-agent minutes ($0.06/min) and Cartesia phone numbers ($0.014/min) on top of the monthly credit allotment; check cartesia.ai/pricing for current numbers since usage-based pricing can change

Who it's for

Developers prototyping a voice agent or TTS feature can start entirely free on the 20K-credit plan, though the Free tier lacks a commercial-use license, which the $5/month Pro plan adds along with instant voice cloning. Teams shipping production phone or in-app voice agents at real call volume are the target for Startup and Scale, where per-minute agent/telephony costs and higher concurrency limits become the deciding factor over raw credit counts.

Frequently asked questions

What does Cartesia cost?

Cartesia runs on a monthly credit system: Free is $0 (20,000 credits), Pro is $5/month (100,000 credits, adds a commercial-use license), Startup is $49/month (1.25M credits), and Scale is $299/month (8M credits), with a custom-priced Enterprise tier above that. On top of monthly credits, voice-agent usage is billed separately at $0.06/minute for agent call time and $0.014/minute for a Cartesia phone number. Check cartesia.ai/pricing for the current numbers, as usage-based AI pricing changes frequently.

Is Cartesia free?

Yes, Cartesia has a real $0/month Free plan with 20,000 monthly credits (about 27 minutes of TTS or roughly 1 hour 51 minutes of speech-to-text), one voice-agent slot and up to 8 concurrent calls. The Free plan does not include a commercial-use license or instant voice cloning — both are unlocked starting on the $5/month Pro plan. There's no time-limited trial; the free credits simply renew each month.

What languages and voices does Cartesia support?

Cartesia's Sonic TTS model is natively multilingual across 40+ languages, with popular locales including American English, Mexican Spanish, Mandarin Chinese, Hindi, Emirati Arabic, French and Brazilian Portuguese called out specifically. Voice cloning output can additionally be localized into 42 languages while preserving the cloned speaker's tone and identity. Exact per-voice and per-language availability can vary by model version, so check Cartesia's languages/voices documentation for the current list before committing to a target market.

Does Cartesia support voice cloning?

Yes, Cartesia offers instant voice cloning from about 10 seconds of reference audio, aiming for high speaker similarity so a brand or personal voice stays consistent at scale. Instant voice cloning is included starting on the $5/month Pro plan (not on Free), and the $49/month Startup plan upgrades to "professional" voice cloning with presumably tighter fidelity/control. Cloned voices can be used to generate speech across Cartesia's 42-language localization set, not just the original recording language.

Can I use Cartesia's voice output commercially?

Only from the Pro plan ($5/month) upward — Cartesia's pricing page explicitly lists a "commercial use license" as a feature added at the Pro tier, implying the Free plan's output is not commercially licensed. Higher tiers (Startup, Scale, Enterprise) retain and build on this commercial license, with Enterprise additionally offering DPAs/BAAs for regulated industries. Confirm the exact license terms on Cartesia's pricing/legal pages before shipping a commercial product on any given tier.

Does Cartesia have an API?

Yes — Cartesia is fundamentally an API product: its Sonic (TTS), Ink (speech-to-text) and Line (voice agents) models are all accessed via a documented REST API at docs.cartesia.ai, with deployment options across cloud, on-premise and on-device. Sonic is built to stream the first byte of audio in about 90ms, which is the core selling point for building responsive, real-time voice agents rather than batch narration. Specific endpoint URLs, authentication flow details and rate limits should be checked in the current docs, since they weren't fully enumerated in the publicly crawlable page content.

Cartesia vs ElevenLabs — how do they compare on latency and price?

On latency, Cartesia's Sonic claims sub-90ms time-to-first-byte, while ElevenLabs' fastest model, Eleven Flash v2.5, claims about 75ms latency and covers 32 languages according to ElevenLabs' own model docs — both are in the same ultra-low-latency class built for real-time voice agents. On price, Cartesia's Free plan gives 20,000 credits/month with paid tiers from $5/month, whereas ElevenLabs' Free plan gives 10,000 credits/month with paid tiers starting at $6/month (Starter) up to $99/month (Pro) and beyond; ElevenLabs also layers in a broader non-voice-agent feature set (sound effects, music, voice design) that Cartesia doesn't offer. The practical choice often comes down to measured latency/quality in your own pipeline plus which platform's voice-agent tooling (Cartesia's Line vs. ElevenLabs' Agents Platform) fits your stack.