# HIIT Interval Timer \| 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/hiit-interval-timer-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 435 App Store ratings · 59 written reviews indexed
- Age rating: 4+
- Requires: iOS 16.0 · 42 MB
- Languages: Korean, Danish, German (Germany), Russian, Malay, Norwegian Bokmål, Swedish, European Spanish, Arabic, American English and 10 more
- Released: 2017-07-15
- Data updated: 2026-09-20
- Monetization: free with in-app purchases
- User reviews in markdown: https://appshunter.io/ios/app/hiit-interval-timer-cero/id1256319392/reviews.md

## What is HIIT Interval Timer | 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.

**One-time purchases**

| Purchase | Price | Type |
| --- | --- | --- |
| Cero Pro | $3.99 | one-time |


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

Overall sentiment: positive

**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

## Recent user reviews (10 of 59)

All indexed reviews: https://appshunter.io/ios/app/hiit-interval-timer-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.

### 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 HIIT Interval Timer | 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)

### 4.1.2 — 2026-09-18

Cero 4.1 makes it faster to build, run and review your workouts:

• Start from new advanced and quick timer templates, including open-ended manual intervals.
• See elapsed time during your workout and track progress with the new wave animation. Wave effects can be switched off separately for simple and advanced timers in Settings.
• Export your workout history as a PDF or CSV file.
• Improved custom interval duplication and timer layouts.

### 4.1.1 — 2026-09-17

Cero 4.1 makes it faster to build, run, and review your workouts:

• Start from new advanced and quick timer templates, including open-ended manual intervals.
• See elapsed time during your workout and track progress with the new wave animation. Wave effects can be switched off separately for simple and advanced timers in Settings.
• Export your workout history as a PDF or CSV file.
• Improved custom interval duplication and timer layouts.

### 4.1.0 — 2026-09-16

Cero 4.1 makes it faster to build, run, and review your workouts:

• Start from new advanced and quick timer templates, including open-ended manual intervals.
• See elapsed time during your workout and track progress with the new wave animation. Wave effects can be switched off separately for simple and advanced timers in Settings.
• Export your workout history as a PDF or CSV file.
• Improved custom interval duplication and timer layouts.

### 4.0.1 — 2026-09-14

Your timer can do a lot more now:

• Adaptive HR can extend recovery until you reach your target heart rate and guide hard efforts with low and high alerts.
• Timer Music lets you choose a default song or set different music for individual intervals.
• Live Activities and updated Dynamic Island layouts keep compatible sessions visible and within reach.
• Home Screen widgets, Siri and Shortcuts make saved timers quicker to start and control.
• Gym Display gives you a clearer view on a large screen or mirrored TV.
• Share and import timers with a file or QR code, review completed sessions in workout history, and protect your setup with automatic iCloud backups.
• A configurable lap stopwatch is now available on iPhone. Countdown and Stopwatch have also arrived on Apple Watch.
• The refreshed design includes a new app icon and improvements to timer reliability, background alerts and heart-rate connections.

A useful update for HIIT, Tabata, circuit training and HYROX preparation.

### 4.0.0 — 2026-09-14

Cero 4.0에서 더 다양하게 운동하세요.

• Adaptive HR은 심박수가 설정한 목표에 도달할 때까지 휴식을 연장할 수 있으며, 고강도 인터벌 중에는 심박수 알림을 제공합니다.
• 타이머 전체 또는 인터벌별로 음악을 선택할 수 있습니다.
• 실시간 현황과 Dynamic Island에서 운동을 확인하고, 위젯, Siri, 단축어로 타이머를 시작하세요.
• 큰 화면에 타이머를 표시하고, 파일이나 QR 코드로 타이머를 공유하거나 가져올 수 있습니다.
• 운동 기록을 확인하고 iCloud 자동 백업으로 설정을 저장하세요.
• iPhone에 랩 기록이 가능한 스톱워치를 추가했습니다. Apple Watch에서도 카운트다운과 스톱워치를 사용할 수 있습니다.
• 디자인을 새롭게 다듬고 타이머, 알림, 심박수 센서 연결의 안정성을 개선했습니다.

## Apps similar to HIIT Interval Timer | Cero

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## More apps by Flawless Studio LLC

- [Irregular Verbs: Learn English](https://appshunter.io/ios/app/irregular-verbs-learn-english/id1543574299)
- [Tabata & HIIT Timer \| Cero Pro](https://appshunter.io/ios/app/tabata-and-hiit-timer-cero-pro/id1569959638)
- [AI Calorie Counter: FitCounter](https://appshunter.io/ios/app/ai-calorie-counter-fitcounter/id6498909414)

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

## Related topics

[fitsifu timer](https://appshunter.io/ios/topics/fitsifu-timer)

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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 2026-09-20.*