Best for
Best for teams transcribing real conversations across accents and languages, including where the audio may not leave their own infrastructure.
- Small and mid-sized
- Enterprise
AI Voice & Speech Comparison
Speechmatics 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 | Speechmatics | Synthflow |
|---|---|---|
| Starting price | lower value From $0.129 / hour of audio Pro tier rate, billed to the second with no commitment. Volume discounts of 20% apply automatically above 500 hours per month for each speech-to-text type, with further discounts above 24,000 hours a year. One credit equals one dollar. | 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 $100 in credit, no card required | Not stated |
| Commercial use | Yes, usage-based | Yes, under an enterprise contract |
| Output | Transcripts, translations and synthesised speech | Voice and chat agents for inbound and outbound phone calls, including white-labelled agents resold under a partner's brand |
| API | Yes, batch and real-time speech-to-text, text-to-speech, translation and a management API | Yes, a public Platform API, plus an MCP server for MCP-capable clients |
| Languages | 55+ languages and dialects for speech-to-text; translation across 69 language pairs | Over 30, plus a multilingual mode that switches languages within one call |
| Hosting | Cloud, CPU or GPU containers, Kubernetes, on-premises virtual appliance, or on-device | Cloud, with region-based hosting |
| Made in | United Kingdom | Not stated |
| Voice cloning | No, the text-to-speech API ships four fixed voices, sarah and theo in British English and megan and jack in American English, and the documentation describes no custom or cloned voice; speed, pitch and emphasis are not adjustable either | 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, streaming transcription returned in under a second, alongside batch transcription of recorded files | 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 |
| Speech-to-speech and dubbing | Audio translation across 69 language pairs, returned as translated transcript rather than dubbed audio; a Voice Agent API is in early access | 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 | Speaker diarization and identification, custom dictionary, language identification, background speech filtering, and speech intelligence for summaries, sentiment, topics and auto-chapters | 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 | Data is not logged as standard; container, Kubernetes, virtual appliance and on-device deployment keep audio inside your own infrastructure | 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 | more entries Cloud (SaaS), Browser-based, On-premise | Cloud (SaaS), Browser-based |
| Support | Email helpdesk | 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 | LiveKit, Pipecat, Vapi, Zapier | more entries HubSpot, Salesforce, Zapier, Cal.com, GoHighLevel, Twilio, Genesys, Avaya, Five9, Cisco, RingCentral |
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The short version
Key Differences
- Starting price Speechmatics From $0.129 / hour of audio Synthflow From $30,000 / year
- Deployment Speechmatics Cloud (SaaS), Browser-based, On-premise Synthflow Cloud (SaaS), Browser-based
- Company size Speechmatics Small and mid-sized, Enterprise Synthflow Enterprise
- Hosting Speechmatics Cloud, CPU or GPU containers, Kubernetes, on-premises virtual appliance, or on-device Synthflow Cloud, with region-based hosting
- Languages Speechmatics 55+ languages and dialects for speech-to-text; translation across 69 language pairs Synthflow Over 30, plus a multilingual mode that switches languages within one call
Every line is one datapoint from the table above, picked automatically. Nothing here is written text.
The trade-offs
Strengths and Limitations
Speechmatics
Strengths
- 55+ languages with explicit accent, dialect and code-switching coverage
- Runs in the cloud, in containers, on-premises or on-device
- $100 in credit to start, with no card required
- Data is not logged as standard
Limitations
- A developer API rather than a ready-made voice studio
- Text-to-speech on the free tier covers English only
- The Voice Agent API is still in early access
- Volume discounts start at 500 hours a month, so small workloads pay the full rate
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
Speechmatics
- Free $0 $100 in credit, no card required. 55+ languages for speech-to-text, 2 concurrent real-time sessions and low-latency English text-to-speech.
- Pro $0.129 Per hour of audio, billed to the second with no commitment. 50 concurrent real-time sessions, 10 file jobs per second and email support.
- Enterprise Not stated Volume-based pricing that scales with usage, unlimited concurrency and no rate limits, custom models, custom vocabularies and formatting rules, and SaaS or on-premises deployment.
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
Speechmatics
- 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
Speechmatics https://www.speechmatics.com · checked against the official source on 2026-08-30
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.