Comparison

HIIT Interval Timer | Cero vs FormCheck

Price, ratings, monetisation and update history for both apps, side by side — with what reviewers say about each.

Head to head
About

HIIT Interval Timer | Cero

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
Read full description

Build an interval workout around the way you train. Cero is a flexible interval timer for HIIT, Tabata, circuit training, WODs and HYROX preparation. Set up a quick work/rest timer or program each interval in detail. Distinct colors, large controls and reliable cues keep you focused on the session instead of the clock. BUILD YOUR SESSION • Set work, recovery, sets, warm-up and cool-down. • Create advanced workouts with custom intervals, colors, icons and intensity levels. • Save, duplicate and reorder timers. • Share timers by file or QR code. • Review completed sessions in workout history. STAY IN THE WORKOUT • Follow compatible sessions with Live Activities and Dynamic Island. • Start saved or recent timers from Home Screen widgets. • Use Siri and Shortcuts to start, pause, resume and stop a timer. • Put Gym Display on a larger screen or mirrored TV. • Choose a default song or assign music to individual intervals. • Customize sounds, voice cues, vibrations and background alerts. TRAIN BY HEART RATE Adaptive HR can extend recovery until you reach your target heart rate, then guide hard efforts with low and high alerts. Pair a Bluetooth heart-rate monitor with iPhone or train with heart-rate data from Apple Watch. COUNTDOWN AND STOPWATCH The built-in countdown and lap stopwatch cover warm-ups, station changes, rest periods and race-day practice. Stopwatch sessions continue after you close and reopen the app. ON APPLE WATCH Run saved workouts from your wrist, follow heart rate and use the standalone countdown and stopwatch. Cero can save completed workouts and estimated calories to Apple Health. Automatic iCloud backups help protect saved timers and custom intervals. Useful for HIIT, Tabata, circuits, EMOM-style workouts, boxing rounds, strength and conditioning, indoor cycling, running intervals and hybrid race preparation. Feedback and suggestions: hi@flawless.studio Terms of Use (EULA): https://www.apple.com/legal/internet-services/itunes/dev/stdeula/

About

FormCheck

This app records and analyzes your exercise movements, measuring symmetry, angles, and pace. It offers live video feedback, customizable exercise templates, and the ability to share libraries with clients. A free version is available for sample analysis.

Highlights
  • Exercise movement and bar path recording
  • Symmetry, angle, and position measurement
  • Live video feedback and alarms
  • Customizable exercise templates
  • Pace and rep tracking
  • Trainer/client sharing of exercise libraries
Features
Read full description

Form Check will record and measure your exercise movement and bar path. Use the measurements systems to measure symmetry, angles or positions of your selected body parts. Build your own targets and alarms and get live video feedback as you exercise. Try out the FREE VERSION option to see how the system analyzes a sample video and exercise. Upgrade to a membership to allow live recording and post processing of your own videos. Form Check will allow you to set a Pace (Reps per Minute) for your set, and will measure each rep in the set to tell you if you are on pace. Select from free exercise templates or build your own. Form Check can be used for Squats, Pullups, Pushups, Deadlift, Lunges, you name it. The system is fully configurable and your imagination is the only limit. Are you a Trainer or a Coach? Sign up to a membership to be able to securely share up to 5 SHARED exercise libraries with your clients. Your clients' exercise results will be automatically shared with you to review and annotate. See how their form compares to yours! Shared libraries are securely and privately managed by Apple's iCloud infrastructure. FormCheck FREE VERSION allows Clients of FormCheck members to process their videos in their shared libraries. Form Check is 100% AD FREE! Form Check does not gather or record any personal information! Notice a bug? Want a feature? Want to get involved? I'd love to hear from you at teamformcheck@gmail.com Follow us on these sites for news and for the FormCheck of the Day: - Instagram @formcheck.ai - Youtube https://www.youtube.com/channel/UClt7IZoBBGiVd6IfHoomBJA - Tutorials: https://www.youtube.com/playlist?list=PLVF2O3v6dytV2TmUInTIQOCnOkxOSD_89 - FormCheck of the Day: https://www.youtube.com/playlist?list=PLVF2O3v6dytXfF3NB79P80uh7FWeGSKFG - Facebook https://www.facebook.com/FormCheckiOSApp

Screenshots

HIIT Interval Timer | Cero4 screens
FormCheck4 screens

Verdict

The call

The clearest difference is ads: FormCheck at none against HIIT Interval Timer | Cero's shown. FormCheck also leads on iOS requirement (14.1 vs 16.0). HIIT Interval Timer | Cero's advantage is review sentiment (75% vs 50%). On price, update cadence, in-app purchases and monetization model 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

CostPrice · In-app purchases · Ads · Monetization

Both are free to download. HIIT Interval Timer | Cero sells 2 in-app purchases, starting at $2.99 per month and FormCheck sells 2 in-app purchases, starting at $3.99 per month. Whichever you choose, the download price is not the number that matters.

UpkeepUpdate frequency

HIIT Interval Timer | Cero ships an update every 3 days, FormCheck every 6 days. The most recent releases landed on October 12, 2026 and September 30, 2026 respectively.

Scorecard3 real differences · 7 level
HIIT Interval Timer | Cero versus FormCheck: the parameters behind the verdict, then further details
ParameterHIIT Interval Timer | CeroFormCheck
PriceFreeFree
Rating4.7 (435 ratings) — better—
Positive reviews74.6% of reviews — better50.0% of reviews
Number of ratings435 — better—
Update frequencyEvery 3 days — betterEvery 6 days
AdsYesNo — better
In-app purchasesYesYes
MonetizationFree with in-app purchasesFreemium
DevicesiPhone, iPad, Apple Watch — betteriPhone, iPod
Requires iOS16.014.1 — better
Further details — not scored
Size43 MB110 MB
Age rating4+4+
DeveloperFlawless Studio LLCThomas Wilson

Customer experience

HIIT Interval Timer | Cero

All ratings435 ratings
Positive92.9%
Neutral3.9%
Negative3.2%
Written reviews59 reviews
Positive74.6%
Neutral10.2%
Negative15.3%

FormCheck

All ratings4 ratings
Positive25.0%
Neutral0.0%
Negative75.0%
Written reviews4 reviews
Positive50.0%
Neutral0.0%
Negative50.0%

Bugs and requests

HIIT Interval Timer | Cero

Reported bugs

4 issues
  • 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

5 requests
  • 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

FormCheck

Not enough reviews yet to summarise bugs or requests.

In-app purchases

2 purchases

HIIT Interval Timer | Cero

Subscriptions1
  • Cero Pro Monthly7 Days trial$2.991 Month
One-time1
  • Cero Pro$14.99
2 purchases

FormCheck

Subscriptions2
  • Monthly Membership1 Month trial$3.991 Month
  • Yearly Membership$28.491 Year

Questions

Is HIIT Interval Timer | Cero free?
HIIT Interval Timer | Cero is free to download, with in-app purchases available.
Is FormCheck free?
FormCheck is free to download, with in-app purchases available.
Do HIIT Interval Timer | Cero or FormCheck have ads?
HIIT Interval Timer | Cero shows ads; FormCheck does not.
Which is updated more often, HIIT Interval Timer | Cero or FormCheck?
HIIT Interval Timer | Cero ships an update every 3 days, and FormCheck every 6 days. Most recently, HIIT Interval Timer | Cero was updated on October 12, 2026 and FormCheck on September 30, 2026.

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