OpenAI Realtime API (gpt-realtime) vs Ultravox

OpenAI Realtime API (gpt-realtime) 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. OpenAI Realtime API (gpt-realtime) starts lower at $0.02 per minute vs $0.05 for Ultravox. On compliance, OpenAI Realtime API (gpt-realtime) additionally documents SOC 2, HIPAA, GDPR. For coding-agent use, OpenAI Realtime API (gpt-realtime) scores higher on agent-friendliness (50 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	OpenAI Realtime API (gpt-realtime)	Ultravox
Starting price	$0.02 minute (audio input)	$0.05 minute
Pricing model	Usage	Usage
Free tier	✗	✗
Self-serve signup	✓	✓
SOC 2	Type II	·
HIPAA	✓	·
GDPR	✓	·
Webhooks	✓	✓
Sandbox	✗	✗
Documented actions	17	20

Full data and citations: OpenAI Realtime API (gpt-realtime) · Ultravox. See more Realtime Voice Agent APIs.