Seconds Interval Timer vs Stack'D Fit
Price, ratings, monetisation and update history for both apps, side by side — with what reviewers say about each.
Seconds Interval Timer
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.
- 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
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Seconds is an interval timer for HIIT, Tabata, EMOM, circuits and any workout built from timed intervals. It calls each interval out loud, keeps running with the screen off, and runs on iPhone, iPad and Apple Watch. Apple has featured it, and Joe Wicks, The Body Coach, has said it is the fitness app he uses more than any other. BUILD ANY WORKOUT - Start from a HIIT, Tabata or circuit template, or build a timer from scratch with sets, rounds and intervals of different lengths. - Chain timers into one compound timer, so a warm-up flows into the main set and then a cool-down. - Color-code every interval so you know what is coming before the beep. - Share a timer with a friend in one tap. HEAR IT, DON'T WATCH IT - Voice cues call out each interval by name and warn you before the next one starts. - Beeps and bells are there too if you would rather not be talked at. - Play your own music, per timer or per interval. Cues duck the music and it comes back up when they are done. - The timer keeps going in the background while you use other apps or the screen sleeps. ON THE GYM FLOOR - A full-screen, color-coded display you can read from across the room, in portrait or landscape. On iPad it uses the whole screen. - A lock button stops a stray tap from pausing your set. APPLE WATCH - Seconds runs on the watch by itself, so the phone can stay in the locker. Timers you build on the phone sync to the wrist, and Quick Intervals builds a basic circuit on the watch itself. MORE TIMERS - A stopwatch that marks your best and worst laps. - A countdown timer with five preset durations (three on Apple Watch). APPLE HEALTH - Save workouts and mindful sessions to Health. With a heart rate monitor connected, Seconds reads your body measurements and year of birth from Health to estimate calories burned. FREE TO TRY, ONE PAYMENT TO UNLOCK - Everything is available from the first launch. Build any timer and run it. - Each timer locks after you run it once. A single in-app purchase removes the lock on every timer you make. SECONDS AND SECONDS PRO - Seconds Pro is the same app, paid once up front, with nothing to unlock. The two are separate products and a purchase in one does not carry over to the other. If you bought Seconds Pro, download Seconds Pro. If you bought the unlock in Seconds, download Seconds and use Restore Purchases.
Stack'D Fit
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For members of Stack'D Fit to reserve their place in a class, sign up for gym events, and general account management like updating headshots and credit card on file.
Screenshots
Verdict
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.
Scored on Price · Rating · Positive reviews · Number of ratings · Update frequency · Ads · In-app purchases · Monetization · Best chart rank · Devices · Requires iOS
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.
| Parameter | Seconds Interval Timer | Stack'D Fit |
|---|---|---|
| Price | Free | Free |
| Rating | 4.7 (24K ratings) — better | — |
| Positive reviews | 75.0% of reviews | — |
| Number of ratings | 24K — better | — |
| Update frequency | Monthly — better | Every 5 weeks |
| Ads | No | No |
| In-app purchases | Yes | No — better |
| Monetization | Free with in-app purchases | — |
| Devices | iPhone, iPad, Apple Watch | iPhone, iPad, iPod |
| Requires iOS | 18.0 | 15 — better |
| Further details — not scored | ||
| Size | 95 MB | 93 MB |
| Age rating | 4+ | 4+ |
| Developer | Runloop Ltd | Stack'D Fit LLC |
Bugs and requests
Seconds Interval Timer
Reported bugs
2 issues- Timer sometimes stops working unexpectedly
- Issues with restoring purchases on new devices
Requested features
5 requests- 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
Not enough reviews yet to summarise bugs or requests.
In-app purchases
Seconds Interval Timer
- Advanced Version$7.99
Stack'D Fit
No in-app purchases
Questions
Is Seconds Interval Timer free?
Is Stack'D Fit free?
Do Seconds Interval Timer or Stack'D Fit have ads?
Which is updated more often, Seconds Interval Timer or Stack'D Fit?
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