Best for
Best for developers building low-latency, real-time voice agents.
- Small and mid-sized
- Enterprise
AI Voice & Speech Comparison
Cartesia vs. Synthflow
At a glance
At a glance
Best for
Best for contact centres and outsourcers that want phone agents built, branded and launched under one contract.
- Enterprise
Cataleo does not name a winner. Both statements come from the vendors themselves.
Full Comparison
| Criterion | Cartesia | Synthflow |
|---|---|---|
| Starting price | lower value Free tier; Pro from $5 / month Usage-based credits and agent minutes. Pro adds a commercial-use license and instant voice cloning. | From $30,000 / year Enterprise contracts start there and are scoped around call volume, concurrency, telephony setup, integrations, security needs and launch support. No self-serve tier is published. |
| Free trial | Free tier with 20,000 credits per month | Not stated |
| Commercial use | Paid | Yes, under an enterprise contract |
| Output | Low-latency real-time speech, instant clone from around three seconds | Voice and chat agents for inbound and outbound phone calls, including white-labelled agents resold under a partner's brand |
| API | Yes | Yes, a public Platform API, plus an MCP server for MCP-capable clients |
| Hosting | Not stated | Cloud, with region-based hosting |
| Voice cloning | Yes, instant cloning from around three seconds, plus a Pro clone trained on 30 minutes or more of audio | Cloning happens in ElevenLabs, not in Synthflow. The voice selector offers Synthflow's own TTS with twelve built-in voices and the ElevenLabs models from Turbo v2 and Flash v2.5 up to v3; a cloned or provider-specific voice is added through Imported > Import Voice by pasting the provider voice ID, or by connecting your own ElevenLabs API key so that account's custom voices appear in the selector. The vendor warns that a synthesiser model your own ElevenLabs plan lacks can mean lower quality or higher latency on your key |
| Real-time use | Yes, real-time text-to-speech (Sonic), built for live voice agents | Yes, live inbound and outbound calls, with IVR handling for outbound agents, voicemail and silence handling, in-call SMS and WhatsApp messaging, and WhatsApp Business calling. The vendor states 99.99% uptime on its own telephony infrastructure |
| Languages | Yes, Sonic 3.6 covers 44 languages natively, chosen per request with a language parameter and regional locale variants | Over 30 languages are listed in the documentation, plus a multilingual mode that switches between English, Spanish, French, German, Hindi, Russian, Portuguese, Japanese, Italian and Dutch within a single call. Speech recognition runs on Deepgram or Synthflow's own engine, which the vendor recommends for non-English |
| Speech-to-speech and dubbing | Yes, a voice changer, plus localization that converts existing audio across the 44 supported languages while holding the speaker's emotion and identity | Not documented. The voice documentation covers text-to-speech for live agents, with a speaker and a synthesis model chosen per agent, and carries no speech-to-speech conversion and no dubbing |
| Editing and controls | Speed 0.6x to 1.5x, volume 0.5x to 2x, an emotion setting (neutral, calm, angry, content, sad) or model-interpreted emotion, custom pronunciation dictionaries, accent selection for multilingual voices and text normalization | Flow Designer, a node-based canvas with conversation, message, branch, jump and custom action nodes, or a simpler prompt builder, plus a multi-agent system for several flows behind one agent, voice model and pacing settings, manual testing, automated simulations and custom evaluations that score calls against business goals |
| Consent and trust | The terms of service forbid publishing audio of another person's voice without that person's express permission, and name deceased people and political candidates explicitly | SOC 2, HIPAA, PCI DSS, GDPR and ISO 27001, with encryption, audit logs and region-based hosting. Per-agent controls decide whether recordings and transcripts are kept at all, cap retention at 30 days, and redact personal data from transcripts, webhook payloads and logs |
| MCP-ready | No | stated Yes |
| Deployment | Cloud (SaaS), Browser-based | Cloud (SaaS), Browser-based |
| Support | Not stated | Email helpdesk |
| Onboarding | Documentation and knowledge base | more entries Documentation and knowledge base, Personal consulting |
| Company size | more entries Small and mid-sized, Enterprise | Enterprise |
| Integrations | Not stated | HubSpot, Salesforce, Zapier, Cal.com, GoHighLevel, Twilio, Genesys, Avaya, Five9, Cisco, RingCentral |
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The short version
Key Differences
- Starting price Cartesia Free tier; Pro from $5 / month Synthflow From $30,000 / year
- Company size Cartesia Small and mid-sized, Enterprise Synthflow Enterprise
- MCP-ready Cartesia No Synthflow Yes
- Commercial use Cartesia Paid Synthflow Yes, under an enterprise contract
- Output Cartesia Low-latency real-time speech, instant clone from around three seconds Synthflow Voice and chat agents for inbound and outbound phone calls, including white-labelled agents resold under a partner's brand
Every line is one datapoint from the table above, picked automatically. Nothing here is written text.
The trade-offs
Strengths and Limitations
Cartesia
Strengths
- Lowest-latency real-time voice for agents
- Instant three-second cloning
- Cost-effective developer API
Limitations
- Less expressive on long-form and audiobook content
- Newer and developer-oriented
Synthflow
Strengths
- No-code Flow Designer with a multi-agent system, so a non-developer can build and change call flows
- Connects to existing telephony and contact centre stacks over SIP, including Genesys, Avaya, Five9, Cisco and RingCentral
- White-labelled deployments for partners reselling voice agents under their own brand
- SOC 2, HIPAA, PCI DSS, GDPR and ISO 27001, with agent-level retention and PII redaction controls
Limitations
- No self-serve or trial tier is published; the only listed plan is an enterprise contract from $30,000 per year
- Pricing is scoped by sales, so the cost of a given call volume is not knowable from the website
- Latency figures differ between the vendor's own pages, so the published number is not a specification to rely on
- A cloned voice has to be created in a separate ElevenLabs account and imported, so it means a second subscription alongside Synthflow
Plans
Pricing
Cartesia
- Free $0 20,000 credits per month plus $1 of prepaid agent usage. Text-to-speech and speech-to-text.
- Pro $5 / month 100,000 credits, a commercial-use license and instant voice cloning.
- Startup $49 / month 1.25 million credits, professional voice cloning and organizations.
- Scale $299 / month 8 million credits, priority support and high concurrency limits.
- Enterprise Not stated Custom credits and agent usage, custom concurrency limits, DPAs/BAAs and SSO.
Synthflow
- Enterprise $30,000 Per year, the stated starting point. Scoped around call volume, concurrency, telephony setup, integrations and security needs, and covers implementation, onboarding, testing, training, launch support and ongoing optimisation, with SLA and support terms set in the contract.
What users say
Review Scores · opens after launch
Cartesia
- Ease of use
- Not rated yet
- User interface
- Not rated yet
- Onboarding
- Not rated yet
- Support and service
- Not rated yet
- Value for money
- Not rated yet
- Features
- Not rated yet
No reviews yet. Be the first to review this tool. Every review is checked for fairness before it appears, and the vendor cannot have one removed.
Synthflow
- Ease of use
- Not rated yet
- User interface
- Not rated yet
- Onboarding
- Not rated yet
- Support and service
- Not rated yet
- Value for money
- Not rated yet
- Features
- Not rated yet
No reviews yet. Be the first to review this tool. Every review is checked for fairness before it appears, and the vendor cannot have one removed.
Where this comes from
Where this comes from
Cartesia https://cartesia.ai · no check date recorded yet
Synthflow https://synthflow.ai · checked against the official source on 2026-09-13
This table lists factual criteria taken from information the vendors publish themselves. For how we put it together, see the methodology.