Know why you win the point.
Rallyline is a tennis app for the Apple Watch. It picks up every stroke from your wrist, you tap who won the point, and after the match it tells you what actually decided it.
Most tennis gadgets count your swings and stop there. We built this because that number never helped anyone play better. What helps is knowing that you lost most of the long backhand rallies in the second set, and that your first serve dropped off when you got tired. That's the kind of thing a coach notices. Now your watch can too.
Join the waitlistBeta testing starts soon. It's free during the beta.
This is the whole on-court interaction. Go ahead and play a game; it keeps real tennis score, deuce and all.
How it works
Wear your watch on your racket hand. That's the one unusual thing we ask. The watch can't feel a swing from the other wrist.
Start a session and play. Rallyline recognises forehands, backhands and serves as you hit them, and records the path and speed of each swing. Nothing to clip on, nothing to set up on a tripod.
Tap after each point. Won or lost. If you want more detail, one extra tap says whether it was a winner, your error, or theirs.
Read your match afterwards. Your iPhone shows every point and every swing, and writes a short note on what to work on, in plain language.
Most of your errors came off the backhand. They clustered in long rallies late in the second set. Work on height and margin over the net when you're stretched. An example of a coaching note from the app.
What you see after a match: the score, a note written the way a coach would say it, your stroke counts, and every point in order. Tap any point to see the swing that ended it, in 3D. (Example data.)
What's in the beta
- Stroke detection for forehands, backhands and serves
- Live tennis scoring on the watch, with deuce, ads and tiebreaks
- 3D swing path, speed and spin for every stroke
- Coaching notes after each match
- Progress across matches
- Racket sensor for racket-head data (prototype, later)
- Coach accounts to follow your students (later)
Straight answers
- Do I need to buy a sensor?
- No. If you have an Apple Watch, you have everything. We're prototyping a small racket sensor for later, but the app works without it.
- Which Apple Watch do I need?
- Any model that runs watchOS 10 or newer, paired with an iPhone on iOS 17 or newer.
- How accurate is it?
- Honest answer: good enough to compare your own swings and spot patterns, not a radar gun. Speeds are estimates from wrist motion. We'll publish real numbers from the beta.
- Do I really have to tap after every point?
- Yes, if you want the coaching notes. The score is what turns swing data into something useful. Practice mode skips it entirely.
- What will it cost?
- Free during the beta. After that, scoring and stroke counts stay free, and coaching notes and trends will be a subscription. We'll tell beta testers the price before anyone is charged.
- What happens to my data?
- It stays on your iPhone and watch. We don't have a server that stores it, and we don't sell it. The privacy policy is short and in plain English.
Get on the waitlist
We'll email you when beta invites go out, and once more at launch. That's it.
Privacy Policy
Privacy Policy
The short version: your tennis data stays on your own iPhone and Apple Watch. We don't run servers that store it, we don't sell it, and we don't use it for advertising.
What the app collects and where it stays
- Motion data. While a session is running, the app reads your Apple Watch's motion sensors to detect strokes. This is processed on the watch. Raw sensor readings are not saved; only the result (stroke type, time and an estimated speed) is kept.
- Session data. Strokes, points you record, scores, and the opponent name you enter are stored on your Apple Watch and iPhone. They are sent from the watch to your phone using Apple's built-in watch connection, not through our servers.
- Apple Health. With your permission, Rallyline saves each session to Apple Health as a Tennis workout. It doesn't read other health data. You can change this permission at any time in the Health app.
What we never do with health data
Data from Apple Health is never used for advertising or marketing, never sold, never shared with third parties, and never stored in iCloud by us. This follows Apple's HealthKit rules.
Purchases
Subscriptions are handled by Apple. We don't receive your payment details. Apple tells us whether a subscription is active so the app can unlock features.
Website waitlist
If you join the waitlist on our website, we collect your email address and use it only to send beta invites and launch news. Our form provider, [FORM PROVIDER], stores it on our behalf. You can unsubscribe from any email or ask us to delete your address.
Deleting your data
You can delete individual sessions in the iPhone app, or delete the app to remove all Rallyline data from your devices. Workouts saved to Apple Health can be removed in the Health app.
Children
Rallyline is not directed at children under 13, and we don't knowingly collect personal information from them. A parent or guardian who believes a child has given us information can contact us to have it removed.
Changes
If the app starts collecting new kinds of data (for example, accounts or cloud backup), we will update this policy and the date above before that change ships.
Contact
Questions or requests: sergiocotal@icloud.com.
Terms of Use
Terms of Use
By using Rallyline you agree to these terms and to Apple's standard Licensed Application End User License Agreement, which also applies to apps downloaded from the App Store.
What Rallyline is
Rallyline is a training aid. Stroke detection, speed figures and coaching notes are estimates based on your watch's motion sensors and the scores you enter. They can be wrong, and they are not professional coaching, medical or fitness advice.
Play safely
Tennis is physical. Warm up, listen to your body, and talk to a doctor before starting a new training routine if you have health concerns. Make sure your watch band is secure; you use your devices on court at your own risk.
Subscriptions
Some features need a paid subscription bought through Apple. Payment is charged to your Apple account. Subscriptions renew automatically unless you turn off auto-renew at least 24 hours before the end of the current period. You can manage or cancel them in your Apple account settings. Refunds are handled by Apple under its policies.
Fair use
Don't reverse engineer, resell or misuse the app, or use it to break any law.
No warranty
The app is provided "as is". To the extent the law allows, we don't promise it will be error-free or always available, and we aren't liable for indirect or consequential losses arising from its use.
Changes
We may update these terms. If a change is significant, we'll tell you in the app before it takes effect.
Governing law
These terms are governed by the laws of [STATE / COUNTRY].