Synthflow AI vs Ultravox

Synthflow AI and Ultravox are both Realtime Voice Agent APIs, compared here on pricing, compliance, capabilities, and developer experience from structured, cited data - not reviews or paid placement. Ultravox starts lower at $0.05 per minute vs $0.09 for Synthflow AI. On compliance, Synthflow AI additionally documents HIPAA, GDPR. For coding-agent use, Synthflow AI scores higher on agent-friendliness (45 vs 20).

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	Synthflow AI	Ultravox
Starting price	$0.09 minute	$0.05 minute
Pricing model	Usage	Usage
Free tier	✗	✗
Self-serve signup	✓	✓
SOC 2	?	·
HIPAA	✓	·
GDPR	✓	·
Webhooks	✓	✓
Sandbox	✗	✗
Documented actions	23	20

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