# Flip Timer & stopwatch vs Acid Interval

The clearest difference is ads: Acid Interval at none against Flip Timer & stopwatch's shown. Acid Interval also leads on rating (5.0 vs 4.6) and update cadence (every 2 weeks vs every 3 months). Flip Timer & stopwatch's advantage is ratings volume (7.6K vs 1) and device support (3 vs 1). On price, in-app purchases and monetization model there is nothing between them.

Both are free to download. Flip Timer & stopwatch sells 3 one-off in-app purchases and Acid Interval sells 1 one-off in-app purchase. Whichever you choose, the download price is not the number that matters.

Acid Interval holds the better App Store score, 5.0 against 4.6. That said, the two scores are not equally well evidenced: Flip Timer & stopwatch has 7.6K ratings behind it against 1, so its average is the more settled of the two.

Flip Timer & stopwatch ships an update every 3 months, Acid Interval every 2 weeks. The most recent releases landed on October 24, 2026 and October 22, 2026 respectively.

## The numbers

| Metric | Flip Timer & stopwatch | Acid Interval |
| --- | --- | --- |
| Price | Free | Free |
| Rating | [4.6 (7.6K ratings)](https://appshunter.io/ios/app/flip-timer-and-stopwatch/id1304344207/reviews) | **[5.0 (1 ratings)](https://appshunter.io/ios/app/acid-interval-focus-timer/id6815378728/reviews)** |
| Number of ratings | **7.6K** | 1 |
| Positive reviews | 68.6% of reviews | — |
| In-app purchases | Yes | Yes |
| Ads | Yes | **No** |
| Update frequency | Every 3 months | **Every 2 weeks** |
| Monetization | Free with in-app purchases | Freemium |
| Size | 46 MB | 1 MB |
| Requires iOS | **15.0** | 17.0 |
| Devices | **iPhone, iPad, iPod** | iPhone |
| Age rating | 4+ | 4+ |
| Developer | [俐 马](https://appshunter.io/developer/1896144174) | [Preston Carr](https://appshunter.io/developer/6815378730) |

## What reviewers say

### Flip Timer & stopwatch

[App page](https://appshunter.io/ios/app/flip-timer-and-stopwatch/id1304344207)

This app offers a full-screen digital timer with a unique flip animation to visualize time progression. It also includes a stopwatch for tracking activities like workouts, study sessions, and work. Customize reminder sounds and background audio for an immersive experience.

**Highlights:** Full-screen digital timer, Flip animation for time visualization, Countdown timer, Stopwatch functionality, Customizable reminder sounds, Background sound options, Keep screen on for progress viewing

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

**In-app purchases (3)**

| Purchase | Price | Billing |
| --- | --- | --- |
| Remove Ads | $0.99 | one-time |
| All the skins | $0.99 | one-time |
| Pro Version | $1.99 | one-time |

**What reviewers like**

- 👍 Simple and straightforward design
- 🚀 Large, easy-to-read display
- 💡 Unique flipping timer interface
- 🕰 Remembers previous time settings
- 👍 Works well for classroom/productivity use

**What reviewers complain about**

- 🐛 Timer sometimes skips seconds or doesn't work accurately
- 💰 Ads are intrusive and disruptive
- 🔒 Paid features should be included in free version
- 🔋 Timer stops working when device is locked or app is in background

**Reported bugs**

- Timer randomly stops counting down
- Unable to stop/reset timer once started
- Ads prevent user from interacting with timer

**Requested features**

- Add option to set timer in hours/minutes/seconds
- Implement repeat/loop functionality for timer
- Allow custom alarm/notification sounds
- Improve landscape mode support


### Acid Interval

[App page](https://appshunter.io/ios/app/acid-interval-focus-timer/id6815378728)

This focus timer offers a visually unique approach to deep work, moving away from traditional interfaces. It provides customizable timers and engaging visual feedback to help users stay on task, even with the screen off. The app prioritizes a distraction-free experience with no account or data syncing required.

**Highlights:** Unique visual interface, Customizable timer intervals, Engaging animation mechanisms, Screen-off notifications, No account or data sync, Phone lock compatibility

**In-app purchases (1)**

| Purchase | Price | Billing |
| --- | --- | --- |
| Acid Interval Pro | $2.99 | one-time |


## Frequently asked questions

### Is Flip Timer & stopwatch free?

Flip Timer & stopwatch is free to download, with in-app purchases available.

### Is Acid Interval free?

Acid Interval is free to download, with in-app purchases available.

### Which has better reviews, Flip Timer & stopwatch or Acid Interval?

Acid Interval is rated higher. Flip Timer & stopwatch averages 4.6 out of 5 from 7.6K ratings, while Acid Interval averages 5.0 from 1 ratings.

### Do Flip Timer & stopwatch or Acid Interval have ads?

Flip Timer & stopwatch shows ads; Acid Interval does not.

### Which is updated more often, Flip Timer & stopwatch or Acid Interval?

Flip Timer & stopwatch ships an update every 3 months, and Acid Interval every 2 weeks. Most recently, Flip Timer & stopwatch was updated on October 24, 2026 and Acid Interval on October 22, 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.*