Best AI Voice Agents · head-to-head
Retell AI vs Synthflow
A sourced, side-by-side comparison for ai voice agents. Retell AI has the lower entry price. Every figure links to the vendor's own page and the date we captured it.
At a glance
- Price: Retell AI $0/mo vs Synthflow $0/mo — Retell AI is cheaper to start.
- Free tier: Retell AI No; Synthflow Yes.
- HIPAA: Retell AI Yes; Synthflow Yes.
Side by side
| Retell AI | Synthflow | |
|---|---|---|
| Entry price | $0/mo (Pay-as-You-Go) | $0/mo (Pay As You Go) |
| Free tier | No | Yes |
| HIPAA (BAA) | Yes | Yes |
| SOC 2 | Yes | Yes |
| GDPR | Yes | Yes |
| Best for | developers | agencies |
Sources — Retell AI: retellai.com (verified 2026-06-15). Synthflow: synthflow.ai (verified 2026-06-15).
Key features
Retell AI: Transparent per-component pricing (LLM + STT + TTS + telephony shown separately); HIPAA BAA available for self-signing on all plans including pay-as-you-go — no enterprise contract required; AI Quality Assurance add-on at $0.10/min with first 100 minutes free; SOC2 Type I & II certified
Synthflow: Modular per-minute pricing: voice engine, LLM, and telephony priced separately so you can BYOT; SOC2 and GDPR on all plans; HIPAA on Enterprise; White-label toolkit with custom domain option; Synthflow Native Telephony on Enterprise