Retell AI vs Synthflow
A side-by-side comparison of capabilities, autonomy, integrations, and pricing to help you choose.
Short answer: choose Retell AI if you want platform to build, test, deploy, and monitor ai voice agents for calls (Autonomous agent, usage); choose Synthflow if you want no-code platform to build and run ai voice agents for phone calls (Autonomous agent, usage).
| Retell AI | Synthflow | |
|---|---|---|
| What it is | Platform to build, test, deploy, and monitor AI voice agents for calls | No-code platform to build and run AI voice agents for phone calls |
| Type | platform | platform |
| Autonomy | Autonomous agent | Autonomous agent |
| Pricing | usage · $0.07/min voice engine (model + telephony billed on top); Enterprise from $8,000 | usage · ~$0.09/min voice engine (LLM + telephony billed on top); free PAYG tier |
| Best for | developers, smb, mid-market, enterprise | smb, mid-market, enterprise, developers |
| Deployment | saas, api | saas, api |
| Modalities | voice, text, api | voice, text, api |
| Models | model-agnostic, gpt, claude | model-agnostic, gpt, proprietary |
| Protocols | rest-api, function-calling | rest-api, function-calling |
| Integrations | Twilio, Telnyx, Vonage, ElevenLabs, PlayHT | Twilio, Telnyx, RingCentral, Vonage, Salesforce, HubSpot |
| Capabilities | 4 documented | 4 documented |
Retell AI
- +Provider-flexible: bring your own telephony, voices, and LLM, or use Retell's built-in carrier
- +Structured Conversation Flow Agents (nodes and transitions) give fine control alongside looser prompt-based agents
- +Usage-based pricing with no mandatory base subscription and free credits to start; built-in testing and monitoring
- -Advertised $0.07/min covers only the voice engine; LLM, telephony, and international add to real per-minute cost
- -Building reliable structured flows for complex calls takes meaningful human setup
Synthflow
- +Genuinely no-code visual builder with fast setup, a common point of praise in reviews
- +In-house telephony plus broad SIP and CRM integration, with a white-label and reseller program for agencies
- +Natural low-latency voices (ElevenLabs) and a free pay-as-you-go tier to start
- -Per-minute cost adds up at volume once LLM and telephony are stacked on the voice-engine rate
- -LLM choice is OpenAI-centric in practice rather than fully model-agnostic
Which should you choose?
Retell AI is platform to build, test, deploy, and monitor ai voice agents for calls, best for developers, smb, mid-market, enterprise. Synthflow is no-code platform to build and run ai voice agents for phone calls, best for smb, mid-market, enterprise, developers. The right choice depends on the autonomy level you want, your existing integrations, and your budget, all compared above.