Comparison

Interval Timer for HIIT | Cero vs AIFYR

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

Head to head
About

Interval Timer for HIIT | Cero

Create custom interval workouts for HIIT, Tabata, and circuit training. Features adaptive heart rate training, Siri integration, and Apple Watch support. Track progress and share your custom routines.

Highlights
  • Customizable interval programming
  • Adaptive heart rate training
  • Siri and Shortcuts integration
  • Apple Watch app
  • Workout history and sharing
  • Live Activities and Dynamic Island support
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

AIFYR

Features
Read full description

Step into a world where each tile holds a challenge, and each challenge brings you closer to self-discovery. This immersive game combines strategy, resource collection, and mindfulness exercises to create a truly unique experience. Move your character through lush landscapes, encounter unexpected tasks designed to boost your mental and physical well-being, and collect tools to unlock new paths. With every step, you'll face exciting tasks that encourage you to focus, relax, and grow. Need to cross a river? Build a bridge! Encountering a tough obstacle? Pick the right tool and break through! From physical exercises to mental puzzles, the challenges are designed to enrich your journey. Make each move count as you score points, unlock new abilities, and turn your gameplay into a rewarding adventure. Are you ready to challenge yourself and explore all that awaits?

Screenshots

Interval Timer for HIIT | Cero4 screens
AIFYR4 screens

Verdict

The call

The clearest difference is ads: AIFYR at none against Interval Timer for HIIT | Cero's shown. Interval Timer for HIIT | Cero's advantage is update cadence (every 3 days vs every 2 weeks). On price, in-app purchases, device support and iOS requirement 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. Interval Timer for HIIT | Cero sells 2 in-app purchases, starting at $2.99 per month and AIFYR sells 4 one-off in-app purchases. Whichever you choose, the download price is not the number that matters.

UpkeepUpdate frequency

Interval Timer for HIIT | Cero ships an update every 3 days, AIFYR every 2 weeks. The most recent releases landed on November 6, 2026 and October 30, 2026 respectively.

Scorecard2 real differences · 8 level
Interval Timer for HIIT | Cero versus AIFYR: the parameters behind the verdict, then further details
ParameterInterval Timer for HIIT | CeroAIFYR
PriceFreeFree
Rating4.7 (438 ratings) — better—
Positive reviews74.6% of reviews—
Number of ratings438 — better—
Update frequencyEvery 3 days — betterEvery 2 weeks
AdsYesNo — better
In-app purchasesYesYes
MonetizationFree with in-app purchases—
DevicesiPhone, iPad, Apple Watch — betteriPhone, iPad
Requires iOS18.017.6 — better
Further details — not scored
Size50 MB66 MB
Age rating4+4+
DeveloperFlawless Studio LLCJosef Anderberg

Bugs and requests

Interval Timer for HIIT | 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

AIFYR

Not enough reviews yet to summarise bugs or requests.

In-app purchases

2 purchases

Interval Timer for HIIT | Cero

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

AIFYR

One-time4
  • 10 Skips$0.99
  • 100skips$0.99
  • 100 Skips$0.99
Show 1 more
  • Premium$3.99

Questions

Is Interval Timer for HIIT | Cero free?
Interval Timer for HIIT | Cero is free to download, with in-app purchases available.
Is AIFYR free?
AIFYR is free to download, with in-app purchases available.
Do Interval Timer for HIIT | Cero or AIFYR have ads?
Interval Timer for HIIT | Cero shows ads; AIFYR does not.
Which is updated more often, Interval Timer for HIIT | Cero or AIFYR?
Interval Timer for HIIT | Cero ships an update every 3 days, and AIFYR every 2 weeks. Most recently, Interval Timer for HIIT | Cero was updated on November 6, 2026 and AIFYR on October 30, 2026.

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