Privacy Policy

1. Who is responsible

Lukas Gerken
Sonnenbergstrass 9B, 8610 Uster, Switzerland
Support and privacy: tennisfeel.com@gmail.com
Account deletion: tennisfeel.deleteacc@gmail.com

TennisFeel is operated by Lukas Gerken as an individual publisher in Switzerland. In this notice, “I”, “me” and “TennisFeel” refer to him. This notice covers the TennisFeel Android and iOS apps, account services, Stringer Pro, direct messaging, support and tennisfeel.com.

I act as controller for account administration, service security, support and website operations. Professional stringers decide the purposes of their own client records and have separate responsibilities. Apple, Google and other independent services also process information under their own notices.

This policy provides information; using the service is not blanket consent to unrelated processing. Where consent is required, it must be obtained separately and can be withdrawn.

2. Information we process and its sources

Information comes from you, your device and use of the service, authentication and purchase providers, and people who share records or communicate with you. A stringer can hold a client record even if that client has no TennisFeel account.

• Account and profile: email address, account identifier, display name, sign-in information, playing level, playing frequency, equipment goals and preferences. Firebase Authentication handles sign-in credentials.
• Equipment and activity: racket and string specifications, setups, stringing history, frequency and tension readings, calculated estimates, training entries, ratings, feedback, dates and notes.
• Messages and sharing: message contents, participant identifiers, timestamps, delivery/read information, shared equipment snapshots, job exchanges and imported copies.
• Stringer Pro records: client names, contact details where entered, linked accounts, equipment, jobs and notes supplied by the stringer or client.
• Safety and preferences: messaging-rule acceptance and version, blocks, reports, restrictions, privacy preferences, request-rate records and deletion requests.
• Technical data: notification tokens, connection and device information, IP addresses received by service providers, and security and operational logs.
• Correspondence: support and deletion emails, beta feedback and correspondence you send through the website.

Age: current account creation asks whether you are 16 or older. It does not require your full birthdate. The retained record includes eligibility, minimum age, declaration method, policy version and time. This is a self-declaration, not verified identity. Older beta builds may request a birthdate to calculate eligibility; the eligibility service does not retain that birthdate in the eligibility record.

Purchases: where paid Pro is offered, verification uses the store/product identifier, transaction reference or purchase token, a random account-link identifier, access status and verification/expiry times. Apple or Google processes payment; TennisFeel does not receive your full payment-card details. Offers and availability depend on the store and app version.

3. Why information is used

Information is used to provide accounts and requested features, synchronize your records, calculate equipment comparisons, deliver messages and notifications, verify purchases, prevent abuse, investigate reports, handle requests and improve the service.

Where the EU or UK GDPR applies, the grounds depend on the purpose:

• Contract: processing necessary to provide requested account, equipment, synchronization, messaging and paid-access services, or take steps you request before an agreement.
• Legitimate interests: proportionate security, fraud prevention, service reliability, support, handling disputes and understanding service use. These interests must be balanced against your rights, particularly for younger users.
• Consent: optional pre-launch emails and other optional processing where consent is requested or legally required. Withdrawal does not affect earlier lawful processing.
• Legal obligations: necessary processing to meet an applicable legal duty or binding authority request.

Required account information is needed to provide an account. Optional preferences, notes, microphone measurements can be declined. Swiss data-protection requirements also apply. An operating-system permission is not consent to unrelated processing.

4. Comfort preferences and sensitive information

TennisFeel helps compare tennis equipment; it is not a medical service. You can describe a preference for comfort without providing a diagnosis or medical history. Please avoid entering medical records, detailed injury information, payment-card details or other unnecessary sensitive information in profiles, messages and client records.

Information about discomfort, symptoms or injuries can still reveal health information, including in older beta records. Changing the wording does not change its sensitivity. Such information is not used for advertising. Contact me to access, correct or remove it. General acceptance of these terms or messaging rules does not provide explicit consent for health-data processing; an additional legal condition is needed wherever applicable law requires it.

5. Microphone, notifications and device storage

When you start a string-frequency measurement, microphone samples are processed on your device to calculate frequency. This measurement feature does not save or upload an audio recording. Readings you save and their associated equipment information may be stored locally and synchronized with your account.

Notifications use device tokens and Apple/Google delivery services. Your device settings determine whether previews appear on a locked screen. You can change microphone access and notification permissions in device settings; refusing microphone permission prevents that measurement feature.

The app stores local records, preferences, authentication state and cached data. Signing out, uninstalling or leaving a beta programme does not delete the cloud account. A website request cannot immediately erase data on an offline device.

6. Direct messaging, shared records and Stringer Pro

Messaging is one-to-one. Information you send becomes available to the recipient, who may copy it. Messages are stored on the service; they are not end-to-end encrypted. Importing equipment or a job creates an independent record in the recipient’s account. A partner may see your display name and playing level.

Messaging-rule acceptance is recorded per account and rule version, not for every conversation. Supported builds offer reporting and blocking. Reports include the selected message, reason and identifiers needed for investigation. I personally handle reports and may review relevant content for safety, support or a valid legal request. Blocking does not erase earlier exchanges.

A professional stringer must inform clients about records they create and have a lawful basis for them. For client records hosted on a stringer’s instructions, the stringer determines their business use; any legally required processing agreement is separate from this public notice. TennisFeel independently administers accounts, security, purchases and support. Clients can contact the stringer or me for help exercising their rights, including when they have no app account.

7. Recommendations, statistics and diagnostics

Equipment scores, simulations and recommendations use equipment characteristics, measurements and your profile/preferences. They are estimates for your decision-making, not decisions intended to have legal or similarly significant effects. Age and purchase checks may restrict access; contact support for review of an incorrect result.

Community comparisons can use equipment, profile, measurement and performance data to produce grouped results. Older beta services may include records without the newer contribution setting. Where your build offers a contribution preference, use it; contact support to confirm or stop inclusion if the control is absent or fails. Removing a name or grouping a small number of records does not necessarily make them anonymous. Identifiable and pseudonymous records remain subject to privacy rights.

Optional Firebase Analytics and automatic Crashlytics collection are disabled in the current app configuration. Essential authentication, synchronization, notifications and operational/security processing still occur. Apple and Google may provide beta feedback and diagnostics under their testing settings. Umami is used by the website only, not inside the TennisFeel app.

8. Website and email contact

GitHub Pages hosts the website. Page and asset requests expose connection information to the hosting service, including IP addresses used for security. The website’s product video is hosted as a site asset, not embedded from YouTube.

Website analytics: the main website currently loads Umami Cloud to measure visits, page performance, referring sites, browser/device characteristics, approximate location and interactions such as video playback, store-link clicks. Custom website analytics events can include selected role and equipment-goal categories, including arm comfort. Email addresses and free-text comments are not included in those custom analytics events. The tracker respects Do Not Track and omits URL query strings and fragments. Umami describes its tracker as cookie-free; that does not mean no information is processed. The standalone privacy and terms pages do not load analytics scripts.

Support and deletion correspondence uses Gmail; Google and your own email provider process delivery and mailbox storage. Opening an email link does not send a request until you send the email. Linked external websites have their own notices.

9. Recipients and international processing

Recipients include Google/Firebase for account, cloud, notification and operational services; Apple and Google for distribution, testing and purchases; GitHub for website hosting; Umami Software, Inc. for website analytics; selected communication partners and stringers; and authorities or advisers where disclosure is legally required or necessary for a legitimate claim. Access is limited to the relevant purpose. TennisFeel does not sell personal information or use it for cross-context behavioural advertising.

Processing is not confined to Switzerland. The service uses functions in Switzerland and the United States. Google, Apple, GitHub and Umami also have international operations, including the United States and European countries. A database’s storage region alone does not determine all authentication, support, logging or backup locations. Umami offers US and EU storage regions, with other operational processing possible outside the selected region.

Providers publish their processing terms and international-transfer arrangements at the links below. Applicable arrangements can include recognized adequacy decisions, relevant Data Privacy Framework participation and standard contractual clauses. Their application depends on the provider, service, destination and contract; this notice does not claim that every transfer is covered by the same mechanism. Contact me for service-specific destination information and copies or details of applicable safeguards, with confidential information protected.

• Firebase privacy and processing terms and Google privacy
• Apple privacy
• GitHub privacy and international transfers
• Umami privacy, processing agreement and subprocessors

10. Retention and security

Retention depends on why information is needed, account status, requests, outstanding disputes, legal duties and provider retention settings:

• Account, equipment and activity: retained for continuing account use until deletion is requested or they are no longer needed. Item deletion may leave synchronization markers temporarily; no automatic inactive-account purge is promised.
• Messages and client/job records: retained for the relevant conversation or client service, subject to deletion requests and the separate responsibilities of recipients and stringers.
• Purchase-access records: retained to verify, restore and administer access and resolve purchase issues. Stores retain their own transaction records independently.
• Support, reports and deletion requests: retained while handling the matter and for any necessary follow-up, proportionate abuse prevention or legal claim. Any justified exception to deletion will be explained.
• Optional update emails: contact details are removed from active mailing use on withdrawal or when the requested communication purpose ends, except minimal suppression or consent evidence where needed.
• Website analytics, logs and backups: subject to the provider’s configured retention and backup cycles. Umami’s published production-retention options vary by plan; they are not a promise of a particular retention period for this account. Contact support for the applicable settings.

There is no claim that deleting an account immediately erases all backup copies, offline devices or independent store records. Retained personal information must have a valid purpose and legal basis. Truly anonymous statistics may be retained; removing only a name or account ID is insufficient to establish anonymity.

Authentication, access controls and encrypted network connections help protect data. No system is completely secure. Where a breach triggers notification duties, I will notify the relevant authority and/or affected people as required.

11. Account deletion

Request deletion at tennisfeel.deleteacc@gmail.com, preferably from your registered email. Identify the account and request deletion of the account and associated personal data. Never send your password. If you no longer control that email, explain this so an alternative ownership check can be arranged.

The public deletion page provides this route without a website login or reinstalling the app. Where available, you can also use Settings → Delete account. If a beta build lacks that option or it fails, email remains available. Requests are handled personally; I will explain any verification needed and the expected completion time, then confirm completion. A request must not be treated as completed solely because the login was removed.

Deletion covers your login and associated private cloud profile, equipment, activity, Pro client/job and purchase-access records. Shared conversations and exchange jobs involving your account are included. Independently imported copies held by other people are not automatically erased from their accounts; contact them or me about personal information in those copies. Limited information may be retained where necessary for a legal obligation or justified claim, with the reason and period explained.

Deleting your account does not automatically cancel a store subscription or request a refund. Manage those separately through Apple or Google; cancellation is not a condition for submitting a deletion request. Recreating an account does not automatically transfer a previous purchase. Contact support for recovery assistance.

12. Your rights

Depending on applicable law, you can request information and access, correction, deletion, restriction, portability of eligible data, and object to processing based on legitimate interests. You can withdraw consent at any time and object to direct marketing. These rights also apply to information a stringer or another user supplies about you, subject to lawful exceptions and other people’s rights.

Contact the privacy email without needing an app account. Proportionate identity checks may be required. Requests will be answered within applicable legal deadlines, with any lawful extension or refusal explained. Exercising rights does not require buying Pro.

You can complain to the Swiss Federal Data Protection and Information Commissioner or your competent EU/EEA, UK or other authority where applicable, without first contacting me.

13. Age and younger users

TennisFeel accounts are for people 16 or older. This is the service’s minimum account age, not a statement that 16 is a universal legal minimum. Users aged 16–17 may still need a parent or guardian’s authorization to enter an agreement or make a purchase under local law. A parent’s store payment does not automatically establish account eligibility or consent to all data processing.

If you believe an under-16 user has an account, contact me to investigate and arrange appropriate restriction or deletion. A guardian may ask for help, subject to verification. Stringers handling younger clients without accounts must limit records to necessary client/equipment information and provide appropriate notices and permissions; creating a client record does not authorize an underage app account.

14. Updates and contact

This version is dated 10 November 2026 and applies when published. Features differ between beta builds and platforms; this notice does not announce that an unavailable feature is live. I will update the policy when processing changes and give appropriate notice of material changes through the service, website or email. New consent will be requested where required; a policy update does not itself authorize an incompatible new use of existing data.

Lukas Gerken
Sonnenbergstrass 9B, 8610 Uster, Switzerland
Support and privacy: tennisfeel.com@gmail.com
Account deletion: tennisfeel.deleteacc@gmail.com