# Interval Timer for HIIT | Cero vs Watch HR

The clearest difference is in-app purchases: Watch HR at none against Interval Timer for HIIT | Cero's 2. Watch HR also leads on ads (none vs shown). Interval Timer for HIIT | Cero's advantage is update cadence (every 3 days vs every 3 weeks). On price, device support and iOS requirement there is nothing between them.

Both are free to download. Interval Timer for HIIT | Cero sells 2 in-app purchases, starting at $2.99 per month. Watch HR asks for nothing beyond the download.

Interval Timer for HIIT | Cero ships an update every 3 days, Watch HR every 3 weeks. The most recent releases landed on November 6, 2026 and October 25, 2026 respectively.

## The numbers

| Metric | Interval Timer for HIIT | Cero | Watch HR |
| --- | --- | --- |
| Price | Free | Free |
| Rating | **[4.7 (438 ratings)](https://appshunter.io/ios/app/interval-timer-for-hiit-cero/id1256319392/reviews)** | — |
| Number of ratings | **438** | — |
| Positive reviews | 74.6% of reviews | — |
| In-app purchases | Yes | **No** |
| Ads | Yes | **No** |
| Update frequency | **Every 3 days** | Every 3 weeks |
| Monetization | Free with in-app purchases | — |
| Size | 50 MB | 1 MB |
| Requires iOS | **18.0** | 18.6 |
| Devices | **iPhone, iPad, Apple Watch** | iPhone, Apple Watch |
| Age rating | 4+ | 17+ |
| Developer | [Flawless Studio LLC](https://appshunter.io/developer/1228312508) | [TRACKTEAM PTY LTD](https://appshunter.io/developer/1067183352) |

## What reviewers say

### Interval Timer for HIIT | Cero

[App page](https://appshunter.io/ios/app/interval-timer-for-hiit-cero/id1256319392)

Create custom interval workouts for HIIT, Tabata, and circuit training. Features adaptive heart rate training, Siri integration, and Apple Watch support. Track progress and share your custom routines.

**Highlights:** Customizable interval programming, Adaptive heart rate training, Siri and Shortcuts integration, Apple Watch app, Workout history and sharing, Live Activities and Dynamic Island support

**Features:** macOS Compatibility, Apple Watch app, Vision Pro support, iPhone Duo support

**In-app purchases (2)**

| Purchase | Price | Billing |
| --- | --- | --- |
| Cero Pro Monthly | $2.99 | per month |
| Cero Pro | $14.99 | one-time |

**What reviewers like**

- 👍 Simple and straightforward
- 👍 Very practical and customizable
- 👍 Great for HIIT and Tabata
- 👍 Clear design and easy to use
- 👍 Good value, no subscription

**What reviewers complain about**

- 🔋 Drains battery
- 🎶 Music playback interrupted
- ⚠️ Ads interrupt timers
- 🔊 Weak or non-functional sound/haptics
- 🔄 Forced updates

**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

**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


### Watch HR

[App page](https://appshunter.io/ios/app/watch-hr/id6783612023)

**Features:** Apple Watch app

**In-app purchases:** none


## Frequently asked questions

### Is Interval Timer for HIIT | Cero free?

Interval Timer for HIIT | Cero is free to download, with in-app purchases available.

### Is Watch HR free?

Watch HR is free to download, with no in-app purchases.

### Do Interval Timer for HIIT | Cero or Watch HR have ads?

Interval Timer for HIIT | Cero shows ads; Watch HR does not.

### Which is updated more often, Interval Timer for HIIT | Cero or Watch HR?

Interval Timer for HIIT | Cero ships an update every 3 days, and Watch HR every 3 weeks. Most recently, Interval Timer for HIIT | Cero was updated on November 6, 2026 and Watch HR on October 25, 2026.

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*Compared by [AppsHunter](https://appshunter.io/) from daily US App Store data. Review summaries are generated from verbatim App Store reviews.*