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 from $0.07/min with LLM included permanently, plus a full workflow, integrations, and compliance platform, and 60 free minutes a month with commercial use.
| Capability | Speechify | Cartesia |
|---|---|---|
| Pricing | From $0.07/min all-in — LLM included · 60 free min/mo | $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 | 60 min/mo, commercial use | 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 from $0.07 a minute on Pro 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 sub-90ms time-to-first-byte on Sonic; SpeechifyAI is sub-300ms. Both numbers sit inside the window where humans hear a response as immediate, so the listener cannot tell the 200ms gap. 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 from $0.07 with the LLM permanently included on every tier, plus the workflow editor, tool calling, telephony, evals, and SOC 2 Type II compliance in the platform fee on streaming latency well inside the conversational-immediate window.