# Interval Timer for HIIT \| Cero — Tabata, Gym & Boxing Workout

> Customizable interval timer for HIIT, Tabata, yoga, and other fitness workouts. (iPhone/iPad app by Flawless Studio LLC.)

- Source: https://appshunter.io/ios/app/interval-timer-for-hiit-cero/id1256319392 (this page in markdown: same URL + `.md`)
- Developer: [Flawless Studio LLC](https://appshunter.io/developer/1228312508)
- Category: Health & Fitness, Sports
- Price: Free with in-app purchases
- Rating: 4.70/5 from 436 App Store ratings · 59 written reviews indexed
- Age rating: 4+
- Requires: iOS 16.0 · 42 MB
- Languages: American English, Arabic, Danish, Finnish, French (France), German (Germany), Hindi, Indonesian, Italian, Japanese and 10 more
- Released: 2017-07-15
- Data updated: 2026-10-20
- Monetization: free with in-app purchases
- User reviews in markdown: https://appshunter.io/ios/app/interval-timer-for-hiit-cero/id1256319392/reviews.md

## What is Interval Timer for HIIT | Cero?

Build an interval workout around the way you train.

Cero is a flexible interval timer for HIIT, Tabata, circuit training, WODs and HYROX preparation. Set up a quick work/rest timer or program each interval in detail. Distinct colors, large controls and reliable cues keep you focused on the session instead of the clock.

BUILD YOUR SESSION
• Set work, recovery, sets, warm-up and cool-down.
• Create advanced workouts with custom intervals, colors, icons and intensity levels.
• Save, duplicate and reorder timers.
• Share timers by file or QR code.
• Review completed sessions in workout history.

STAY IN THE WORKOUT
• Follow compatible sessions with Live Activities and Dynamic Island.
• Start saved or recent timers from Home Screen widgets.
• Use Siri and Shortcuts to start, pause, resume and stop a timer.
• Put Gym Display on a larger screen or mirrored TV.
• Choose a default song or assign music to individual intervals.
• Customize sounds, voice cues, vibrations and background alerts.

TRAIN BY HEART RATE
Adaptive HR can extend recovery until you reach your target heart rate, then guide hard efforts with low and high alerts. Pair a Bluetooth heart-rate monitor with iPhone or train with heart-rate data from Apple Watch.

COUNTDOWN AND STOPWATCH
The built-in countdown and lap stopwatch cover warm-ups, station changes, rest periods and race-day practice. Stopwatch sessions continue after you close and reopen the app.

ON APPLE WATCH
Run saved workouts from your wrist, follow heart rate and use the standalone countdown and stopwatch.

Cero can save completed workouts and estimated calories to Apple Health. Automatic iCloud backups help protect saved timers and custom intervals.

Useful for HIIT, Tabata, circuits, EMOM-style workouts, boxing rounds, strength and conditioning, indoor cycling, running intervals and hybrid race preparation.

Feedback and suggestions: hi@flawless.studio

Terms of Use (EULA): https://www.apple.com/legal/internet-services/itunes/dev/stdeula/

## Key features

- Customizable interval timers
- Simple and advanced timer modes
- Create and save multiple workout settings
- Apple Watch compatibility with heart monitor
- Automatic calorie tracking to Apple Health
- Cross-device sync

## Pricing and in-app purchases

Base price: Free.

**Subscriptions**

| Subscription | Price | Period |
| --- | --- | --- |
| Cero Pro Monthly | $2.99 | per month |

**One-time purchases**

| Purchase | Price | Type |
| --- | --- | --- |
| Cero Pro | $14.99 | one-time |


## What do users think of Interval Timer for HIIT | Cero?

Reviews of Interval Timer for HIIT | Cero are mostly positive: the Health & Fitness app is rated 4.7/5 from 436 App Store ratings. What users like most: simple and straightforward, very practical and customizable. Top complaints: drains battery, music playback interrupted. Summarized from real user reviews.

**Pros**

- 👍 Simple and straightforward
- 👍 Very practical and customizable
- 👍 Great for HIIT and Tabata
- 👍 Clear design and easy to use
- 👍 Good value, no subscription
- 👍 Works as expected
- 👍 Versatile for various workouts
- 👍 Intuitive and functional

**Cons**

- 🔋 Drains battery
- 🎶 Music playback interrupted
- ⚠️ Ads interrupt timers
- 🔊 Weak or non-functional sound/haptics
- 🔄 Forced updates
- 🧭 Back button change on Apple Watch

**Commonly reported bugs**

- App runs in background draining battery
- Rotation broke after update
- Apple workout app overrides Cero app on Apple Watch
- Interval signals too weak or not working

**Most requested features**

- Ability to group timers
- Option to add warm-up and cool-down features
- Ability to type numbers for time adjustment
- Timer sounds through headphones or interrupting music
- Ability to change exercise names

## Is Interval Timer for HIIT | Cero safe?

Interval Timer for HIIT | Cero appears safe based on user ratings. The AppsHunter Safety Score for Interval Timer for HIIT | Cero is 93 out of 100. This assessment is based on 436 user ratings, with an App Store average of 4.7 out of 5. Of 436 App Store ratings, 92.9% point to a safe experience, 3.9% suggest some concerns, and 3.2% point to a risky experience.

## Is Interval Timer for HIIT | Cero legit?

Interval Timer for HIIT | Cero appears to be a legitimate app. The AppsHunter Legitimacy Score for Interval Timer for HIIT | Cero is 95 out of 100 points across 7 verification signals from App Store and developer data.

## Recent user reviews (10 of 59)

All indexed reviews: https://appshunter.io/ios/app/interval-timer-for-hiit-cero/id1256319392/reviews.md

### 1/5 — 평생이용 결제 했는데 앱을 바꿔버리네

*2026-09-16*

아니 PRO앱 평생이용 결재해서 쓰고 있는데 갑자기 해당지역에서 사용이 제한된다고 나오고 다시 기본앱에서 PRO결재하라고 하는 건 무슨 경우야?

**Developer response:** 안녕하세요! 저희 앱에는 지역 제한이 없으며 전 세계 어디에서나 사용하실 수 있습니다.

결제 화면(paywall)에서 **구독 복원(Restore Subscriptions)** 버튼을 눌러 주세요.

문제가 계속된다면 support@cero.app 으로 문의해 주세요.

감사합니다!

### 5/5 — Cero

*2026-02-15, version 3.7.3*

Dommage que l'on puisse pas changer le nom des exercices

### 5/5 — Excellent

*2026-02-10*

Works as it should.

**Developer response:** Thank you so much for your feedback! 💚

### 1/5 — Ads interrupt timers

*2025-12-23, version 3.7.3*

Why would I bother with this?

### 3/5 — Parfait

*2025-05-20, version 3.7.1*

L’application est très bien faite, tant visuellement, que dans sa compréhension

### 5/5 — Awesome!

*2025-01-23, version 3.5.7*

Very simple and straightforward 😎

### 5/5 — Great

*2024-12-30*

Best I have used

**Developer response:** Thanks for your comment and feedback GerNob! 💚

### 5/5 — HIIT

*2024-12-16, version 3.5.7*

Parfait

### 4/5 — Great simple workout timer app

*2024-10-24, version 3.5.7*

App works great for creating flexibility routines.
Would love for there to be a way to group timers together to better manage related timers.

### 5/5 — Great

*2024-09-08, version 3.5.7*

Love it

## Frequently asked questions about Interval Timer for HIIT | Cero

### What does the Interval Timer | Cero app do?

This app serves as a versatile interval timer designed to enhance a wide range of workouts, including HIIT, Tabata, running, yoga, and strength training. It offers intuitive controls and customizable features to help users manage their workout intervals effectively.

### What are the key features of Cero?

Key features include simple and advanced timer modes, the ability to create and save custom intervals with unique icons and colors, automatic calorie expenditure tracking to Apple Health, and seamless syncing of timers and settings across all your devices. It also offers Apple Watch compatibility with a heart monitor.

### Is Cero free to use?

The app is free to download and use, offering a robust set of features. It also includes in-app purchases, suggesting that some advanced functionalities or customization options might be available for purchase.

### What devices is Cero compatible with?

Cero is designed for use on iOS devices and is also compatible with Apple Watch, providing a heart monitor for outdoor activities. The app automatically syncs settings across all your devices, ensuring a consistent experience.

### How can Cero help with my workouts?

Cero helps users stay on track with their fitness goals by providing a clear and customizable interval timer. Whether you're doing HIIT, Tabata, or yoga, the app allows you to set up precise intervals, track your progress, and monitor calorie expenditure, making your workouts more efficient and effective.

## Version history (last 5 releases)

### 4.4.0 — 2026-10-19

Cero 4.4 is ready for iPhone Duo:

• Unfolded, Cero makes the most of the larger display: timers split along the fold, and Settings shows each option beside its list.
• Use Cero in Split View and drag timers, QR codes and workout recaps to the app beside it.
• Folded, Cero fits the cover display, with menus and screens sized to match.
• Interface refinements: primary buttons show their titles in green, VoiceOver stays on custom intervals, Apple Watch sound changes show right away, and full screens stay full on large iPhones turned sideways.

### 4.3.0 — 2026-10-12

Cero for Apple Watch, rebuilt from the ground up.

• A redesigned Watch app that's faster and easier to read mid-workout
• Workouts run as Apple Watch workout sessions with live heart rate and save to Health
• Follow and control a Watch workout from your iPhone with a Live Activity
• New complications and a Smart Stack widget show the current interval and time left
• Quick timer, countdown and stopwatch redesigned for the wrist, with Always On support
• Your timers and appearance sync from your iPhone

### 4.2.2 — 2026-10-10

Cero 4.2 makes your progress easier to see and share:

• New workout recaps show time, intervals, estimated calories and heart rate when available. Share your recap as an image.
• The stopwatch now charts laps live and shows lap insights. Sessions are saved when you reset, with history you can export as PDF or CSV.
• Advanced timers have clearer interval bars and progress, plus refreshed setup screens and timer cards.
• Manage Live Activities in Settings on supported devices. Privacy choices and other controls are clearer, too.

### 4.2.1 — 2026-09-28

Cero 4.2 makes your progress easier to see and share:

• New workout recaps show time, intervals, estimated calories, and heart rate when available. Share your recap as an image.
• The stopwatch now charts laps live and shows lap insights. Sessions are saved when you reset, with history you can export as PDF or CSV.
• Advanced timers have clearer interval bars and progress, plus refreshed setup screens and timer cards.
• Manage Live Activities in Settings on supported devices. Privacy choices and other controls are clearer, too.

### 4.2.0 — 2026-09-24

Cero 4.2 makes your progress easier to see and share:

• New workout recaps show time, intervals, estimated calories, and heart rate when available. Share your recap as an image.
• The stopwatch now charts laps live and shows lap insights. Sessions are saved when you reset, with history you can export as PDF or CSV.
• Advanced timers have clearer interval bars and progress, plus refreshed setup screens and timer cards.
• Manage Live Activities in Settings on supported devices. Privacy choices and other controls are clearer, too.

## Apps similar to Interval Timer for HIIT | Cero

| App | Rating | Price | Category |
| --- | --- | --- | --- |
| [Interval Timer: PureHIIT](https://appshunter.io/ios/app/interval-timer-purehiit/id1198752738) | 4.8 (296) | Free | Health & Fitness |
| [Interval Timer X Workout Timer](https://appshunter.io/ios/app/interval-timer-x-workout-timer/id1448144846) | 4.8 (686) | Free | Health & Fitness |
| [HIIT timer chronometer gym](https://appshunter.io/ios/app/hiit-timer-chronometer-gym/id1086940926) | 4.4 (37) | Free | Health & Fitness |
| [Interval Timer: Tabata & HIIT](https://appshunter.io/ios/app/interval-timer-tabata-and-hiit/id6443672034) | 4.9 (384) | Free | Health & Fitness |
| [Interval Timer: HIIT Workout](https://appshunter.io/ios/app/interval-timer-hiit-workout/id1596127692) | 4.9 (246) | Free | Health & Fitness |
| [Interval Timer: Tabata Timer](https://appshunter.io/ios/app/interval-timer-tabata-timer/id1579228573) | 4.5 (149) | Free | Health & Fitness |

## More apps by Flawless Studio LLC

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All apps by Flawless Studio LLC: https://appshunter.io/developer/1228312508

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*Data collected daily from the US App Store and indexed by [AppsHunter](https://appshunter.io/). User reviews are verbatim App Store reviews. Ratings, prices and chart positions refresh continuously; this snapshot is from 2026-10-20.*