Cartesia (Line) is ultra-low-latency voice infrastructure with a $0.06/min headline, but telephony adds $0.014/min and the "LLM included" is a limited-time promo. SpeechifyAI is all-in with the LLM included permanently, plus a full workflow, integrations, and compliance platform, quoted per contract.
| Capability | SpeechifyAI | Cartesia |
|---|---|---|
| Pricing | Quoted per contract, all-in with the LLM included | $0.06/min + $0.014/min telephony; LLM free is a promo |
| LLM cost | Included, no passthrough — permanent | Free for now (limited-time promo) |
| Free tier | Pilot scoped with our team | 20K credits/mo, no commercial use on Free |
| Workflow editor | Visual + code, deterministic | Build-your-own |
| Integrations | Tool calling + webhooks | Build-your-own |
| Voice library | 20+ curated real-time voices | Sonic voices (cloning on paid tiers) |
| Compliance | SOC 2 Type II | SOC 2 |
Cartesia's $0.06 a minute headline only includes the LLM right now; it is a promotional rate that becomes a different price the day the promo ends. SpeechifyAI is one all-in rate with the LLM permanently included with the LLM permanently included, the same number on the pricing page next quarter and next year, plus a workflow editor, tool calling, and webhooks in that rate rather than a separate stack assembled around it.
Cartesia claims very low time-to-first-byte on Sonic; SpeechifyAI is <100ms. Both are low-latency enough for real-time use. What a listener can tell is whether the agent followed the script when it mattered, whether the tool call returned the right answer, and whether the simulated test caller would have caught the regression before this real customer hit it.
SpeechifyAI is a single per-minute rate with the LLM permanently included, plus the workflow editor, tool calling, telephony, evals, and SOC 2 Type II compliance, on streaming latency well inside the conversational-immediate window.
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