Cartesia (Sonic) vs OpenAI Text to Speech (gpt-4o-mini-tts / tts-1)

Cartesia (Sonic) and OpenAI Text to Speech (gpt-4o-mini-tts / tts-1) are both Text-to-Speech APIs, compared here on pricing, compliance, capabilities, and developer experience from structured, cited data - not reviews or paid placement. OpenAI Text to Speech (gpt-4o-mini-tts / tts-1) starts lower at $15 1m characters vs $50 for Cartesia (Sonic). Cartesia (Sonic) offers a free tier while OpenAI Text to Speech (gpt-4o-mini-tts / tts-1) does not, so Cartesia (Sonic) is easier to trial before committing. For coding-agent use, Cartesia (Sonic) scores higher on agent-friendliness (50 vs 30).

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	Cartesia (Sonic)	OpenAI Text to Speech (gpt-4o-mini-tts / tts-1)
Starting price	$50 1M characters	$15 1M characters
Pricing model	Hybrid	Usage
Free tier	✓	✗
Self-serve signup	✓	✓
SOC 2	Type II	Type II
HIPAA	✓	✓
GDPR	✓	✓
Webhooks	✗	✗
Sandbox	✗	✗
Documented actions	17	7

Full data and citations: Cartesia (Sonic) · OpenAI Text to Speech (gpt-4o-mini-tts / tts-1). See more Text-to-Speech APIs.