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.
Retell AI has the lower entry price — Retell AI starts at $0/mo, Synthflow at $0/mo. Free tier: Retell AI No, Synthflow Yes. HIPAA: Retell AI Yes, Synthflow Yes.
As of 2026-06-15 · figures link to their source below
Side by side
Retell AI
$0/mo entrySynthflow
$0/mo entrySources — 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