Comparison

Interval Timer for HIIT | Cero vs KnowMood

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

KnowMood

This app helps you track your daily moods and emotions through simple check-ins. Visualize your feelings in a colorful jar, add context with activities and notes, and gain insights into patterns and trends over time. It offers a private space for self-reflection with optional iCloud backup and no ads.

Highlights
  • Simple mood check-ins
  • Visual Mood Jar
  • Add feelings, activities, and notes
  • Mood trend and pattern analysis
  • Cycle tracking integration
  • Home Screen widgets
  • Optional iCloud backup
Features
Read full description

KnowMood is a mood tracker and private journal to understand your feelings and what feels helpful. Your mood can change throughout the day. Keep a mood diary of those moments, what was happening, and what you tried afterward. Explore everyday patterns and revisit experiences you found helpful, so you have something to refer to when deciding what to try next. KEEP A DAILY JOURNAL, ONE MOMENT AT A TIME • Capture a stressful morning and a peaceful evening with separate check-ins. Record as often as you want throughout the day. • Add specific feelings, your energy level, or a short note to remember more about each moment. • Keep it simple when you need to. Everything beyond your mood is optional. CONNECT YOUR FEELINGS WITH EVERYDAY LIFE • Record sleep, work, movement, time with others, and other life factors alongside your mood. • Note what you needed at the time, such as rest or support. • Keep the context behind your feelings without having to explain everything or make a plan. REMEMBER WHAT YOU TRIED • Return to a check-in and add what you actually did afterward, such as taking a walk, resting, or talking with someone. • Note whether the experience felt helpful, didn't seem to help, felt worse, or left you unsure. • Add more follow-ups as things unfold, keeping the original moment and what happened afterward together. LOOK BACK WHEN A FEELING RETURNS • Choose a mood or feeling to explore the life context, times of day, and energy levels recorded alongside it. • Open matching entries to revisit the experiences behind the patterns. • Filter for check-ins with a follow-up you marked helpful. Consider what fits today, then record how your next attempt feels. EXPLORE YOUR FEELINGS AND MOOD PATTERNS • Feelings & Context: See your most-recorded feelings, then tap one to explore the context and original entries. • Mood Trend: Follow your recorded mood over time and see how recent weeks compare. • Mood Mix: See how often you recorded each mood for a broader picture than one memorable day. • Mood and Daily Life: Compare moods recorded alongside sleep, work, movement, and other life factors to notice associations worth exploring. • Mood and Your Cycle: View mood and cycle records together. Compare completed cycles to see whether similar mood changes appear again. MAKE ROOM FOR EVERYDAY SELF-CARE • Use your mental health journal to reflect on stressful days and save moments when you feel calm, connected, or proud. • Watch your check-ins collect in a colorful Mood Jar and revisit them in your History calendar. • Keep reflection close with Home Screen and Lock Screen widgets, daily affirmations, and optional reminders. • Choose a Mood Style you enjoy to make your journal feel more personal. KEEP A PRIVATE DIARY, WITHOUT AN ACCOUNT • Your journal entries are stored on your device, with optional iCloud backup. • No account to create. No ads to interrupt your time looking back. START FREE, EXPLORE MORE WHEN YOU'RE READY • Free: Mood check-ins, optional details, follow-ups, Mood Jar, History, reminders, cycle recording, and the default Mood Style. • Premium: Personal Patterns, Look back, and additional Mood Styles. Start with how you feel today. Build a record you can turn to tomorrow. Terms of Use: https://sites.google.com/view/mood-tracker-daily-moments/terms-of-use Privacy Policy: https://sites.google.com/view/mood-tracker-daily-moments/privacy-policy

Screenshots

Interval Timer for HIIT | Cero4 screens
KnowMood4 screens

Verdict

The call

The clearest difference is ads: KnowMood at none against Interval Timer for HIIT | Cero's shown. KnowMood also leads on rating (5.0 vs 4.7). Interval Timer for HIIT | Cero's advantage is ratings volume (438 vs 2) and update cadence (every 3 days vs every 10 days). On price, in-app purchases, monetization model 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

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 KnowMood sells 3 in-app purchases, starting at $7.99 per month. Whichever you choose, the download price is not the number that matters.

ReceptionRating · Positive reviews · Number of ratings

KnowMood holds the better App Store score, 5.0 against 4.7. That said, the two scores are not equally well evidenced: Interval Timer for HIIT | Cero has 438 ratings behind it against 2, so its average is the more settled of the two.

UpkeepUpdate frequency

Interval Timer for HIIT | Cero ships an update every 3 days, KnowMood every 10 days. Both last shipped on November 6, 2026.

Scorecard4 real differences · 6 level
Interval Timer for HIIT | Cero versus KnowMood: the parameters behind the verdict, then further details
ParameterInterval Timer for HIIT | CeroKnowMood
PriceFreeFree
Rating4.7 (438 ratings)5.0 (2 ratings) — better
Positive reviews74.6% of reviews—
Number of ratings438 — better2
Update frequencyEvery 3 days — betterEvery 10 days
AdsYesNo — better
In-app purchasesYesYes
MonetizationFree with in-app purchasesFreemium
DevicesiPhone, iPad, Apple Watch — betteriPhone, iPad
Requires iOS18.017.0 — better
Further details — not scored
Size50 MB45 MB
Age rating4+12+
DeveloperFlawless Studio LLCYINGJING ZHUO

Customer experience

Interval Timer for HIIT | Cero

All ratings438 ratings
Positive92.9%
Neutral3.9%
Negative3.2%
Written reviews59 reviews
Positive74.6%
Neutral10.2%
Negative15.3%

KnowMood

All ratings2 ratings
Positive100.0%
Neutral0.0%
Negative0.0%

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

KnowMood

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
3 purchases

KnowMood

Subscriptions2
  • Monthly Premium$7.991 Month
  • Yearly Premium7 Days trial$34.991 Year
One-time1
  • Lifetime Premium$59.99

Questions

Is Interval Timer for HIIT | Cero free?
Interval Timer for HIIT | Cero is free to download, with in-app purchases available.
Is KnowMood free?
KnowMood is free to download, with in-app purchases available.
Which has better reviews, Interval Timer for HIIT | Cero or KnowMood?
KnowMood is rated higher. Interval Timer for HIIT | Cero averages 4.7 out of 5 from 438 ratings, while KnowMood averages 5.0 from 2 ratings.
Do Interval Timer for HIIT | Cero or KnowMood have ads?
Interval Timer for HIIT | Cero shows ads; KnowMood does not.
Which is updated more often, Interval Timer for HIIT | Cero or KnowMood?
Interval Timer for HIIT | Cero ships an update every 3 days, and KnowMood every 10 days. Most recently, Interval Timer for HIIT | Cero was updated on November 6, 2026 and KnowMood on November 6, 2026.

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