Serve Review

Serve Review looks at your tennis serve and tells you what it actually did. Record a few serves on your phone, or pick a clip you already have. Serve Review finds each serve, measures your body through it, and shows you the numbers — plus how much you varied from one serve to the next. WHAT IT MEASURES • Knee bend at the deepest point — the one number with a real reference: pros reach roughly 100–120° • Contact height, relative to your own height • Torso rotation between the backswing and contact • Toss drift — how straight your tossing arm travelled • Weight shift, swing time, arm extension • Consistency — how much each of those varied across your serves HONEST ABOUT ITS LIMITS A single phone camera sees a flat projection of a three-dimensional motion. We measured that error against public motion-capture data instead of guessing at it, and the app says out loud which numbers are…