Retell AI vs Synthflow AI

Retell AI and Synthflow AI are both Realtime Voice Agent APIs, compared here on pricing, compliance, capabilities, and developer experience from structured, cited data - not reviews or paid placement. Retell AI starts lower at $0.06 per minute vs $0.09 for Synthflow AI. On compliance, Retell AI additionally documents SOC 2. For coding-agent use, Retell AI scores higher on agent-friendliness (65 vs 45).

Comparedby a transparent data-readiness score computed from each API's published, sourced fields. No reviews, no paid placement. How we rank.

Data last verified 2026-06-21, with every field cited on each profile.

Head-to-head, from published, cited fields (auto-generated; no paid placement)
Field	Retell AI	Synthflow AI
Starting price	$0.06 minute	$0.09 minute
Pricing model	Usage	Usage
Free tier	✗	✗
Self-serve signup	✓	✓
SOC 2	Type II	?
HIPAA	✓	✓
GDPR	✓	✓
Webhooks	✓	✓
Sandbox	✗	✗
Documented actions	29	23

Full data and citations: Retell AI · Synthflow AI. See more Realtime Voice Agent APIs.