Deliberate practice, made measurable.
TopSpin started from a simple frustration: most tennis apps count what you did, not what you should do next. They log reps and rallies, but they don't tell you that your elbow drops at contact, or that the cross-court topspin you love is two degrees away from spraying long. So we built the tool we actually wanted: real video analysis backed by real physics, instead of another plan that ignores how you hit.
Who it's for
Improving players
You practise regularly and want each session to target a real weakness, not just bank volume.
Coaches
A second set of eyes that quantifies what you already sense, and turns it into prescribed drills.
The curious
You like that a forehand is also a nonlinear dynamical system, and want to see that made tangible.
How the pipeline fits together
Four stages, one clean flow. Each stage stands on its own.
Clip to angles
A pose model finds your joints in each frame, in the browser, and picks out the contact moment.
Angles to feedback
We compare your contact angles to sensible targets and score each joint, so you see what's off.
Flaws to practice
Your ranked flaws become a prioritised, time-boxed session pulled from a tagged drill catalogue.
Practice to prediction
The Ball Lab runs real flight physics and chaos analysis so you can dial in spin, angle, and margin.
See it on your own stroke.
It runs entirely on your machine. No account, nothing uploaded to the cloud.
Open the app