No app. No hardware. Just your phone.
Pose detection runs on your phone in the browser, so there's nothing to install and no account to create. Your sessions are saved only in your browser. Video is never recorded or uploaded.
The optional AI Coach is a preview: it shows example responses, and when you tap it, it sends only your session numbers (rep timings, form angles or lap times, and an age band), never video, location or your name.