🤖 Large Language Models

Claude Cracks Open a Gym App's Hidden API—And Builds Your Export Tool

Stuck with workout data trapped in a slick gym app? One dev let Claude loose with mitmproxy. It didn't just sniff the API—it reverse-engineered, coded a CLI, and started coaching lifts.

theAIcatchup Apr 08, 2026 3 min read
Terminal showing mitmdump capturing Liftoff API traffic with Claude's API schema diagram

⚡ Key Takeaways

  • Claude uses mitmproxy to fully reverse-engineer Liftoff's tRPC API without human packet reading. 𝕏
  • The resulting Go CLI exports workouts, stats, and trends—installable via Homebrew. 𝕏
  • AI loops back: extracts data, then coaches training, hinting at agentic future for personal data. 𝕏
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Originally reported by dev.to

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