# Seconds Interval Timer vs Stack'D Fit

The clearest difference is in-app purchases: Stack'D Fit at none against Seconds Interval Timer's 1. Stack'D Fit also leads on iOS requirement (15 vs 18.0). On price, update cadence, ads and device support there is nothing between them.

Both are free to download. Seconds Interval Timer sells 1 one-off in-app purchase. Stack'D Fit asks for nothing beyond the download.

Seconds Interval Timer ships an update monthly, Stack'D Fit every 5 weeks. The most recent releases landed on September 30, 2026 and September 20, 2026 respectively.

## The numbers

| Metric | Seconds Interval Timer | Stack'D Fit |
| --- | --- | --- |
| Price | Free | Free |
| Rating | **[4.7 (24K ratings)](https://appshunter.io/ios/app/seconds-interval-timer/id475816966/reviews)** | — |
| Number of ratings | **24K** | — |
| Positive reviews | 75.0% of reviews | — |
| In-app purchases | Yes | **No** |
| Ads | No | No |
| Update frequency | **Monthly** | Every 5 weeks |
| Monetization | Free with in-app purchases | — |
| Size | 95 MB | 93 MB |
| Requires iOS | 18.0 | **15** |
| Devices | iPhone, iPad, Apple Watch | iPhone, iPad, iPod |
| Age rating | 4+ | 4+ |
| Developer | [Runloop Ltd](https://appshunter.io/developer/325563420) | [Stack'D Fit LLC](https://appshunter.io/developer/1728263301) |

## What reviewers say

### Seconds Interval Timer

[App page](https://appshunter.io/ios/app/seconds-interval-timer/id475816966)

This app provides a versatile interval timer for various workout types like Tabata, HIIT, and circuit training. It features a clear, full-screen display, customizable alerts, and background operation. Users can also utilize a stopwatch and countdown timer, with integration for Apple Health.

**Highlights:** Full-screen colored display, Templates for HIIT, Tabata, Circuit Training, Voice and audio alerts, Music assignment per interval, Background operation, Apple Health integration, Stopwatch and countdown timer

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

**In-app purchases (1)**

| Purchase | Price | Billing |
| --- | --- | --- |
| Advanced Version | $7.99 | one-time |

**What reviewers like**

- 🚀 Great workout app
- 👍 Customizable and user-friendly
- 🔒 Reliable and stable
- 💡 Versatile for various workouts
- 👍 Easy to create and edit timers

**What reviewers complain about**

- 🐛 Occasional audio issues
- 🔍 Limited Apple Watch integration
- 💰 Paid version required for full functionality
- 🕰️ Time-consuming to set up complex workouts

**Reported bugs**

- Timer sometimes stops working unexpectedly
- Issues with restoring purchases on new devices

**Requested features**

- Ability to change beep/alert volume independently
- Option to delay transition between intervals
- Sync workouts across devices
- More preset workout templates
- Heart rate monitoring integration


### Stack'D Fit

[App page](https://appshunter.io/ios/app/stackd-fit/id6760706014)

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

**In-app purchases:** none


## Frequently asked questions

### Is Seconds Interval Timer free?

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

### Is Stack'D Fit free?

Stack'D Fit is free to download, with no in-app purchases.

### Do Seconds Interval Timer or Stack'D Fit have ads?

Neither Seconds Interval Timer nor Stack'D Fit shows ads.

### Which is updated more often, Seconds Interval Timer or Stack'D Fit?

Seconds Interval Timer ships an update monthly, and Stack'D Fit every 5 weeks. Most recently, Seconds Interval Timer was updated on September 30, 2026 and Stack'D Fit on September 20, 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.*