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Side-by-side: what they do, what they cost, what Kai actually thinks. Pass up to 4 tools via ?tools=claude,chatgpt,gemini.
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Cartesia
S
ElevenLabs
S
OpenAI Voice / Realtime
S
TaglineUltra-low-latency voice. Built for realtime agents.The voice gold standard. Cloning + TTS + dubbing.ChatGPT's voice + the Realtime API for developers.
Categoryvoicevoicevoice
PricingFree tier + usage-based APIFree + $5-$330/moVoice included with ChatGPT Plus; Realtime API by usage
Best forDevelopers building voice agents, phone bots, interactive apps.Podcasts, audiobooks, video VO, multilingual content.Voice chat users, developers building voice agents on OpenAI.
Strengths
  • < 90ms latency — the fastest in the market
  • Sonic model sounds natural
  • Developer-friendly API
  • Most natural-sounding voices
  • Multilingual voice cloning
  • Great API
  • Advanced Voice Mode feels genuinely conversational
  • Realtime API enables true two-way voice apps
  • Built into ChatGPT
Weaknesses
  • Fewer voices than ElevenLabs
  • Less consumer-facing brand
  • Pricing gets steep for production use
  • Some voices sound over-polished
  • Pricey for production apps
  • Less voice variety than ElevenLabs
  • Platform lock-in
Kai's verdictS-tier for realtime. If latency matters more than voice catalog, start here.S-tier. Category leader. Nothing else is close yet.S-tier for conversation. A-tier for TTS. Complement to ElevenLabs, not replacement.
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