Privacy policy

Effective October 27, 2026 (updated the same day). OnlyLines is made by Mauricio Lupi, an independent developer. Contact: support@onlylinestennis.com.

Without an account

You can record and review without signing in. Everything stays on your iPhone: the video, a small session log, scores you keep on your Apple Watch, and voice notes (beta). Point and rally finding runs on the phone. Voice notes are turned into text on the phone by Apple's speech engine.

If you use the Apple Watch app, it records a Tennis workout to Apple Health on your devices. OnlyLines doesn't read your health data and never sends it anywhere.

If you sign in

You sign in with Apple or with a one-time code sent to your email. We keep your email address (or the private address Apple gives you), an account ID, and your settings, such as whether you share sessions with the team.

Cloud backup. While you're signed in, the app backs up each session over Wi-Fi: the video, its session log (date, length, camera settings, phone battery and temperature level, how the phone was tilted, and your watch taps and scores), voice notes (beta), the points spreadsheet and the list of rallies found. Each account can only reach its own files. Everything travels encrypted (HTTPS). During the beta, backups are limited to 30 hours of video a month and 100 GB in all. A video may be removed from your phone 7 days after it's safely in the cloud, and it keeps playing from there. You can change that in Settings.

How we use it

Only to run OnlyLines for you: to sign you in, keep and play back your sessions, send you sign-in codes, answer your support emails and, if you choose to share, improve the tracking. We don't use your data for anything else, and we don't use it for a new purpose without asking you first.

Sharing with the OnlyLines team

This is off unless you turn on "Share my sessions with the OnlyLines team" in Settings › Account. If you turn it on, the OnlyLines team (the developer and the people building OnlyLines with him) can watch and download your backed-up sessions to improve line calls and shot tracking. To do that work we use AI tools, including Anthropic's Claude, which may process your shared videos, logs and voice-note text. We keep their option to train on our data turned off, and they may not use it for anything else. You can turn sharing off at any time; ask us and we'll delete any copies we downloaded.

What the app looks at in your video

To find serves, rallies and shots, the app and our tools look at sound and at body positions (where arms and legs are) in the video. They don't recognize faces or work out who anyone is.

Companies that help run OnlyLines

• Supabase: accounts and the session list (United States).
• Cloudflare: video storage, this website and email forwarding.
• Resend: sends the sign-in code emails.
• Apple: Sign in with Apple, TestFlight, and crash reports when you choose to share them.

They handle data only to provide their service to us, under agreements that require them to protect it at least as well as this policy does. OnlyLines contains no advertising or analytics software, and we never sell or rent your data or share it for advertising. We don't track you across other companies' apps or websites, so the app doesn't ask for tracking permission. Your data is stored in the United States.

Keeping it safe

Data travels encrypted. Your cloud files are private to your account and opened only through short-lived signed links. Your sign-in stays in your iPhone's Keychain. No system is perfectly secure, but we limit who can reach your data to the people and services named here.

People in your videos

Your recordings can show other players. Please let them know you're filming. If you appear in someone's shared session and want it removed, write to us.

Your choices, keeping and deleting

You can see your sessions in the app at any time, and turn sharing off in Settings › Account. To get a copy of what we hold, correct it, or have it deleted, email support@onlylinestennis.com; we answer within 30 days. Our website and app don't change anything when your browser sends "Do Not Track", because we don't track you.

We keep your cloud files until you delete them. Deleting a session from the cloud (the session's delete button › Delete from phone and cloud) removes its video and files. Deleting your account (Settings › Account › Delete account) removes your account, every file in your cloud space and your settings right away, and disconnects Sign in with Apple. Videos on your phone stay on your phone.

Children

OnlyLines isn't meant for children under 13, and we don't knowingly collect their information.

Changes

If this policy changes, we'll update the date above and tell testers in the app or by email.