cero
Back to Cero

CERO / FLAWLESS STUDIO

Terms &
privacy.

How Cero works, what happens to your data, and the choices you have.

Last updated

01 / THE APP

About Cero

Cero is an interval timer operated by Flawless Studio LLC, a United States company, for iPhone, iPad and Apple Watch. It helps you build and run workouts, use countdowns and a stopwatch, and follow your training with optional health and device integrations.

This page covers the Cero app and this website. You do not need to create a Cero account to use the timer. Apple services and optional integrations may require their own accounts or permissions. Contact us at support@cero.app.

02 / USING CERO

Terms of use

Your app license

Cero is licensed through the App Store under Apple’s Standard End User License Agreement. That agreement governs your license, permitted use, intellectual property, termination, warranties and liability. This page explains Cero’s features, purchases and data practices; it does not replace that license or limit rights that cannot be excluded under applicable law.

Use Cero lawfully and respect other people’s rights. Do not interfere with its operation, bypass purchase restrictions, or distribute content you are not entitled to share. Third-party names and trademarks belong to their respective owners; references to training formats do not imply endorsement or affiliation.

Train within your limits

Cero is a fitness timing tool, not a medical device or a source of medical advice. Heart-rate targets, adaptive recovery and calorie estimates are informational and may be inaccurate. Choose workouts appropriate to your health and ability, stop if you feel unwell, and seek qualified advice when needed. Do not use Cero for emergencies or safety-critical monitoring.

Devices, availability and your content

Features depend on your app version, device, operating system, permissions and connected services. Audio, notifications, background execution and sensor readings can be affected by device settings or interruptions. Check your setup before relying on workout cues.

You retain rights to the workout content you create. Keep a backup of important timers and review files before sharing them. Updates may change features or compatibility; descriptions do not promise indefinite support for a particular device or third-party service. Applicable consumer protections continue to apply.

03 / CERO PRO

Purchases & subscriptions

Cero offers free features and optional Cero Pro access. Available plans can include a monthly subscription and a one-time lifetime unlock. The App Store purchase screen shows the price, included access, billing period and any trial offer before you confirm.

  • Subscriptions: payment is handled by Apple. Subscriptions renew automatically unless canceled before renewal under Apple’s billing terms.
  • Trials: eligibility and duration are shown at purchase. An eligible trial converts to the displayed paid subscription unless canceled in time. Apple advises canceling a free or discounted trial at least 24 hours before it ends.
  • Lifetime access: a one-time unlock does not renew. It provides the Cero Pro entitlement offered at purchase; it is not a promise that the app or external services will operate forever.
  • Managing access: manage or cancel a subscription in your Apple Account’s subscription settings. Deleting Cero does not cancel a subscription. Use Restore Purchases in Cero with the Apple Account used to purchase.

Refund requests are handled through Apple, subject to its rules and your statutory rights. See Apple’s subscription instructions or visit Apple’s purchase support. Flawless Studio does not receive your full payment-card details.

04 / YOUR INFORMATION

Privacy & data

Flawless Studio LLC is responsible for the personal information processed to operate Cero and acts as its data controller where applicable. Cero handles the information needed to run your workouts, remember your preferences, provide optional features and understand app reliability. Some information stays on your devices; some is processed by the services described below.

Timers, history and settings
Saved workouts, custom intervals, completed-session history, stopwatch state and preferences are stored on your device. Workout definitions and custom intervals can also be backed up to your private iCloud database. Apple Watch sync transfers workout information between your paired devices.
Health and heart rate
With your permission, Cero can read heart rate and body mass from Apple Health and write workouts and heart-rate samples. It can estimate workout calories and use heart rate from Apple Watch or a paired Bluetooth sensor. Age and heart-rate settings you enter support adaptive recovery and effort alerts. These features are optional; HealthKit readings are not used by Cero to target advertising.
App activity and diagnostics
Firebase services process app interactions, device and app information, installation identifiers, crash reports and performance information. Workout events include interval durations, set counts and counts of interval types. These help us understand use, troubleshoot failures and improve Cero.
Purchases
Apple and RevenueCat process purchase and subscription records, transaction information and app-user identifiers to validate payments, restore purchases and determine Pro access. A RevenueCat identifier can be generated without creating a Cero account.
Advertising
The free app can show Google AdMob ads. Its SDK may process IP addresses, approximate location inferred from them, device identifiers, ad interactions and diagnostic data for advertising, measurement and fraud prevention. Access to Apple’s advertising identifier depends on your tracking permission.
Permissions and support
Notifications use device tokens and permission settings. Camera access supports scanning shared workouts; music access supports the tracks you choose. When you email support, we receive your email address, message and anything you attach. Avoid sending health information or other sensitive details unless needed for your request.
This website
The current pages do not include analytics scripts, advertising cookies or a sign-in form. Hosting infrastructure can receive standard request information, including IP address, requested URL and browser details. Following an external link takes you to a service with its own privacy practices.

Where data-protection law requires a legal basis, providing requested services and validating purchases involves performing a contract; support, reliability and security may rely on legitimate interests; legal recordkeeping may rely on legal obligations. Optional health access and processing that requires consent rely on your permission or consent. Reading this notice is not itself consent to optional processing.

05 / CONNECTED SERVICES

Who processes information

Cero uses Apple services for distribution, purchases, private iCloud backups, Apple Health and device integrations; Google services for analytics, crash and performance reporting, remote configuration, messaging and advertising; and RevenueCat for purchase validation and subscription access.

Flawless Studio LLC is based in the United States. Our service providers may also process information in the United States or other countries outside your location, under their service terms and applicable data-transfer arrangements. Their documentation explains their roles and practices:

When you share a timer by file or QR code, recipients receive the information included in that export. Review it first, especially workout names and custom intervals. Information may also be disclosed when required by law or necessary to investigate abuse or protect legal rights.

06 / IN YOUR HANDS

Your choices & rights

You can manage Health access, notifications, Bluetooth, camera, music and tracking permissions in your Apple device settings. Withdrawing a permission can disable the related feature. A tracking choice does not automatically turn off every form of app analytics or diagnostics.

You can delete saved timers and custom intervals in Cero and manage Cero’s backups and iCloud access separately. Manage or delete Health records in Apple Health. Uninstalling the app does not necessarily delete iCloud backups, Health records, purchase records or information already processed by service providers.

Depending on your location, you may have rights to access, correct, delete or receive a copy of your personal data; restrict or object to processing; withdraw consent; and complain to your local data-protection authority. Email support@cero.app to make a request. We may need information to verify the request and locate the relevant records. We cannot directly retrieve data that exists only on your device or in Apple services under your control.

Cero is not directed at children under 13. If local law requires a higher age or a parent’s permission, those requirements apply. Contact us if you believe a child has provided personal information without the necessary permission.

07 / LOOKING AFTER DATA

Retention & security

Local workout data remains until removed through app or device controls. Cloud backups and Health records have separate storage and deletion controls. Support correspondence and service records are retained for the purpose they were collected, including resolving requests, maintaining purchase access, preventing abuse and meeting applicable recordkeeping requirements. Retention depends on the type of record, active service, provider configuration and legal requirements.

Device protections, Apple’s private CloudKit database and provider security measures help protect information. No storage or transmission method is completely secure. Protect your device and Apple Account, and avoid including sensitive information in shared workout files.