# HIIT Interval Timer | Cero vs Odonlight

The clearest difference is in-app purchases: Odonlight at none against HIIT Interval Timer | Cero's 1. Odonlight also leads on ads (none vs shown). HIIT Interval Timer | Cero's advantage is update cadence (every 3 days vs every 35 months). On price, device support and iOS requirement there is nothing between them.

Both are free to download. HIIT Interval Timer | Cero sells 1 one-off in-app purchase. Odonlight asks for nothing beyond the download.

HIIT Interval Timer | Cero ships an update every 3 days, Odonlight every 35 months. The most recent releases landed on September 25, 2026 and September 24, 2026 respectively.

## The numbers

| Metric | HIIT Interval Timer | Cero | Odonlight |
| --- | --- | --- |
| Price | Free | Free |
| Rating | **[4.7 (435 ratings)](https://appshunter.io/ios/app/hiit-interval-timer-cero/id1256319392/reviews)** | — |
| Number of ratings | **435** | — |
| Positive reviews | 74.6% of reviews | — |
| In-app purchases | Yes | **No** |
| Ads | Yes | **No** |
| Update frequency | **Every 3 days** | Every 35 months |
| Monetization | Free with in-app purchases | — |
| Size | 42 MB | 69 MB |
| Requires iOS | 16.0 | **15.6** |
| Devices | iPhone, iPad, Apple Watch | iPhone, iPad, iPod |
| Age rating | 4+ | 17+ |
| Developer | [Flawless Studio LLC](https://appshunter.io/developer/1228312508) | [Silversalud](https://appshunter.io/developer/1531298685) |

## What reviewers say

### HIIT Interval Timer | Cero

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

This interval timer app enhances various workouts like HIIT, Tabata, and yoga with intuitive design and customizable timer modes. Create and save custom intervals, track calorie expenditure, and sync settings across devices, including Apple Watch.

**Highlights:** 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

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

**In-app purchases (1)**

| Purchase | Price | Billing |
| --- | --- | --- |
| Cero Pro | $3.99 | 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


### Odonlight

[App page](https://appshunter.io/ios/app/odonlight/id6467665544)

**Features:** macOS Compatibility, Vision Pro support

**In-app purchases:** none


## Frequently asked questions

### Is HIIT Interval Timer | Cero free?

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

### Is Odonlight free?

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

### Do HIIT Interval Timer | Cero or Odonlight have ads?

HIIT Interval Timer | Cero shows ads; Odonlight does not.

### Which is updated more often, HIIT Interval Timer | Cero or Odonlight?

HIIT Interval Timer | Cero ships an update every 3 days, and Odonlight every 35 months. Most recently, HIIT Interval Timer | Cero was updated on September 25, 2026 and Odonlight on September 24, 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.*