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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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Duolingo Max
A
ChatGPT
S
Cartesia
S
TaglineDuolingo + AI. Explain My Answer + Roleplay features.The default. Strongest ecosystem + best multimodal breadth.Ultra-low-latency voice. Built for realtime agents.
Categoryeducationchatvoice
Pricing$30/mo (or ~$168/yr)Free + $20/mo Plus + $200/mo ProFree tier + usage-based API
Best forLanguage learners who've outgrown basic Duolingo.General use, voice chat, image generation, first-time AI users.Developers building voice agents, phone bots, interactive apps.
Strengths
  • Explain My Answer = personal tutor for every mistake
  • Roleplay = real conversation practice
  • Gamification that actually sticks
  • Great voice mode
  • Huge plugin/custom GPT ecosystem
  • Strong image generation (DALL-E built in)
  • Code Interpreter
  • < 90ms latency — the fastest in the market
  • Sonic model sounds natural
  • Developer-friendly API
Weaknesses
  • Pricey vs free Duolingo
  • Conversation AI still stiff sometimes
  • Reasoning quality varies by mode
  • Can be verbose
  • Confabulates on niche facts
  • Fewer voices than ElevenLabs
  • Less consumer-facing brand
Kai's verdictA-tier. If you already love Duolingo, worth it. If starting fresh, try ChatGPT Voice instead.S-tier all-rounder. If you want one tool that does everything okay-to-great, this is it.S-tier for realtime. If latency matters more than voice catalog, start here.
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