HIIT Interval Timer | Cero vs TimerFlex

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/

TIMERFLEX – INTERVAL & WOD TIMER The smartest workout timer for serious athletes. Snap a photo of any whiteboard. Describe your session in plain text. TimerFlex builds the entire workout — rounds, intervals, rest — instantly with AI. ——— AI WORKOUT GENERATOR Point your camera at a gym whiteboard or type your workout. AI reads it and sets up the complete timer in seconds. No programming. No fumbling. Just press go. APPLE WATCH SYNC Full timer on your wrist the moment you start. See rounds, phases, and time remaining without touching your phone. Haptic cues keep you on pace. Start and pause from your wrist. REAL-TIME HEART RATE & CALORIES Live BPM and active energy during every session via HealthKit. Know exactly how hard you're working without leaving the timer. 5 PURPOSE-BUILT FORMATS Not a generic countdown. Each format knows exactly what it's doing: • For Time — race the clock, finish as fast as possible • AMRAP — maximum rounds in a fixed window • EMOM — new movement every minute, automatically • Tabata — 20s work, 10s rest, 8 rounds, handled • Custom — chain any combination into one session No manual resets. No counting rounds in your head. TimerFlex handles all of it. 1RM CALCULATOR Built into every setup screen. Enter your max and get instant percentage breakdowns for every lift. VOICE COACH & AUDIO CUES Countdown calls, phase announcements, halfway alerts. Eyes on your reps, not your screen. LARGE DISPLAY & LANDSCAPE MODE Numbers big enough to read from across the gym. Rotate for maximum visibility mid-set. WORKOUT HISTORY & MONTHLY STATS Every session logged automatically with mood, duration, and notes. Monthly Wrapped gives you your longest streak, total time, and favorite format so you can see your training compound over time. SAVE, FAVORITE & REBUILD Save any workout as a template. Favorite your go-to sessions. Retry any past workout in one tap. NOTES & PHOTO ATTACHMENTS Attach whiteboard photos or text notes to any session. Your workout context, always with your data. EXPORT & BACKUP Export your full history as CSV or JSON. Your data, your way, always portable. ——— BUILT FOR • CrossFit WODs & box sessions • HYROX training blocks • HIIT & interval circuits • Tabata (20s work / 10s rest) • EMOM (Every Minute on the Minute) • AMRAP (As Many Rounds As Possible) • Home gym, garage & travel workouts • Benchmark WODs: Murph, Cindy, Fran ——— TIMERFLEX PRO Unlock unlimited AI Generator, Custom Workout Builder, premium voices and sounds, heart rate insights, Monthly Wrapped, photo notes, workout export, Apple Watch sync, and zero ads. Monthly · Quarterly · Annual — your choice. ——— Privacy Policy: https://plainworks.co/timerflex/privacy-policy Terms of Use: https://plainworks.co/timerflex/terms