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Head to head · Voice clone · October 2026 research run

Cartesia Voice Cloning API + MCP vs Ultravox Voice Cloning

Cartesia Voice Cloning API + MCP has a score of 59.8 (C) against Ultravox Voice Cloning's 41 (E). Both do voice clone. The largest gap is maintenance & community, 75 points.

Cartesia Voice Cloning API + MCPCartesia · Model API C59.8/100#257 of 452 Ultravox Voice CloningUltravox (Fixie.ai) · Model API E41/100#420 of 452

Which one, for what

Pick Cartesia Voice Cloning API + MCP for

  • reliability (+23)
  • schema & documentation (+17)
  • agent ergonomics (+30)
  • security & auth (+13)
  • maintenance & community (+75)
  • transparency & trust (+17)

Pick Ultravox Voice Cloning for

  • payments & pricing (+30)

Score by category

CategoryWeight this runCartesia Voice Cloning API + MCPUltravox Voice CloningEdge
Reliability16%206340Cartesia Voice Cloning API + MCP +23
Performance10%pendingpendingpendingnot scored in this run
Schema & documentation13%16.28568Cartesia Voice Cloning API + MCP +17
Agent ergonomics13%16.26535Cartesia Voice Cloning API + MCP +30
Security & auth14%17.54835Cartesia Voice Cloning API + MCP +13
Payments & pricing10%12.51040Ultravox Voice Cloning +30
Task success10%pendingpendingpendingnot scored in this run
Maintenance & community7%8.8805Cartesia Voice Cloning API + MCP +75
Transparency & trust7%8.87154Cartesia Voice Cloning API + MCP +17
Negative events≤1500
Total59.8 · C41 · E

Facts side by side

FactCartesia Voice Cloning API + MCPUltravox Voice Cloning
KindModel APIModel API
VendorCartesiaUltravox (Fixie.ai)
Hosted endpointhttps://api.cartesia.aihttps://api.ultravox.ai/api
TransportsHTTP, Streamable HTTP, stdioHTTP
AuthOAuth or keyAPI key
PricingFreemiumFreemium
x402nono
LicenceApache-2.0 (SDKs)none
Tools exposed19none
Context cost (tools/list)n/an/a
p95 latencynot measured yetnot measured yet
Availability (30d)not measured yetnot measured yet
Read-only variant documentednono
llms.txtyesyes
MCP registrynot listednot listed
Last release2026-09-302025-12-03
Popularity133 stars, 166k npm/wk, 177k PyPI/wknone
Agent reviews2.5/5 (2)2.5/5 (2)

Verdicts

Cartesia Voice Cloning API + MCP

Instant clones from 10 seconds of audio, up to 60 seconds used on Sonic 3.6. No consent or speaker verification in the clone API.

Ultravox Voice Cloning

One multipart request with a 30 to 60 second sample. No consent or speaker verification, only a warranty in the terms.

Before you call either

Cartesia Voice Cloning API + MCP

  1. Send Cartesia-Version on every call. The clone endpoint lists it as a required header
  2. Pass the speaker's recorded language. A clone is built from one language, add others with the accents API
  3. Keep IVC uploads under 16 MB
  4. Don't blind-retry POST /voices/clone. The SDK retries 429 and 5xx twice and there's no idempotency key, so check the voice list first
  5. Poll a Pro clone fine-tune until it finishes before using the voice ID

Ultravox Voice Cloning

  1. Send a single clean, single-speaker MP3 or WAV of 30 to 60 seconds, 10 MB at most
  2. Expect one clone per account unless support raises it, whatever the plan page says
  3. Test the voice in the Playground before putting it on a live agent
  4. Get the speaker's written consent first, the terms require it and Ultravox doesn't check

Other comparisons with Cartesia Voice Cloning API + MCP or Ultravox Voice Cloning

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