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OpenAI Voice / Realtime
S
Cartesia
S
Hume AI
A
TaglineChatGPT's voice + the Realtime API for developers.Ultra-low-latency voice. Built for realtime agents.Voice AI that reads + expresses emotion.
Categoryvoicevoicevoice
PricingVoice included with ChatGPT Plus; Realtime API by usageFree tier + usage-based APIFree tier + pay-as-you-go
Best forVoice chat users, developers building voice agents on OpenAI.Developers building voice agents, phone bots, interactive apps.Therapy apps, customer service, any voice agent where emotion matters.
Strengths
  • Advanced Voice Mode feels genuinely conversational
  • Realtime API enables true two-way voice apps
  • Built into ChatGPT
  • < 90ms latency — the fastest in the market
  • Sonic model sounds natural
  • Developer-friendly API
  • Detects + mirrors emotional tone
  • EVI (Empathic Voice Interface) feels different
  • Expressive voice output
Weaknesses
  • Pricey for production apps
  • Less voice variety than ElevenLabs
  • Platform lock-in
  • Fewer voices than ElevenLabs
  • Less consumer-facing brand
  • Niche use case
  • Pricing ramps fast
Kai's verdictS-tier for conversation. A-tier for TTS. Complement to ElevenLabs, not replacement.S-tier for realtime. If latency matters more than voice catalog, start here.A-tier in its niche. The only one that actually gets emotion right.
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