Comparison

Periodic Timer vs Hydra Flow Daily

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

Head to head
About

Periodic Timer

This app provides a simple, repeating interval timer that can run in the background without distracting you. It offers customizable alerts, quick start options, and prevents your screen from locking while active. Ideal for various activities like fitness, cooking, and learning.

Highlights
  • Repeating interval timer
  • Background operation
  • Customizable alerts (vibration/sound)
  • Prevent lockscreen
  • Shake to start
  • Multiple timer output modes
Features
Read full description

Keep track of time without being distracted by the device! Simple and easy timer that repeats at your chosen interval. FEATURES - Vibration, if sound is off. - Works in the background. - 3 timer output modes: intervals, total time, countdown. - You can cancel or pause the timer with help of a notification. - Quick Start from icon. - Shake To Start - can be enabled in settings. - Prevent Lockscreen - another useful setting, the screen will not lock, while the timer is running. USE CASES Here is a list of known use cases based on the real feedback: Fitness and health: - Stretching - Stationary bicycle (interval training) - On a treadmill - For HIIT - Jogging - Timed medication - Boxing Cooking - While frying potatoes - Roasting steaks - Checking an over or a grill to prevent burning Learning & science - Foreign language learning - As a lab timer - Periodic data collection - Speech training - Presentation timing Other - Mindfulness - Communication - To have a sense of time flying away :) HELP Q: Why the timer doesn't work in the background? A: You should allow notifications. Q: How to turn off the sound and turn on the vibration? A: On the device, turn the Silent Mode on. (Side Switch) Q: Alert is limited for 5 seconds! A: Go to Settings app, then Periodic Timer > Notifications > Banner Style > Persistent. Q: How to switch the Timer Output Mode? A: To switch the Output Mode touch the timer display at the top of the screen. Q: What is Shake To Start for? A: Shake To Start setting allows to start/cancel the timer by shaking the device. Thus, you don't touch the screen, what can be useful while cooking, for example. In order for this mode to work, the app should be open. If you still have questions or suggestions, you can visit the support page (https://goo.gl/forms/pggVBcaBxdW85EGE3), the Facebook group (http://www.facebook.com/groups/PeriodicTimer/) or you can email me (periodictimer.sup@gmail.com). If you like the app - please, rate it!

About

Hydra Flow Daily

Features
Read full description

Hydra Flow is a calm, distraction-free water tracker. One tap logs a sip, a cup or a bottle. A ring, bottle or body silhouette fills as you drink, and gentle reminders stop the moment you reach your goal. LOG IN ONE TAP • Quick-add buttons for 100 ml, 250 ml and 500 ml (or oz) • 60+ drinks: water, coffee, tea, juice, sports drinks, milk and more, each counted with its real hydration value • Undo any entry with one tap • Today's log shows every drink with its time WIDGETS AND SIRI • Home Screen widget with tap-to-log buttons, no need to open the app • Lock Screen widgets show today's progress next to the clock • "Hey Siri, log water in Hydra Flow" and "Check my hydration in Hydra Flow" A GOAL THAT FITS YOU • Personalised daily goal from your weight, height, age and sex (IOM guidelines) • Weather-aware suggestion: on hot days Hydra Flow proposes a higher goal for today • Adjustable any time from Settings STAY CONSISTENT • Smart reminders every 1–4 hours inside the hours you choose, paused once the goal is reached • Streaks, weekly consistency and monthly goals • Week, month and year history with a clean chart APPLE WATCH • Log water from your wrist and see today's ring • Syncs with iPhone PRIVATE BY DESIGN • No account, no ads, no tracking • Optional Apple Health sync (writes water intake) • Optional iCloud sync between your devices Three appearances (Deep, Spa, Cloud), metric or imperial units, and a week that starts on the day you choose.

Screenshots

Periodic Timer4 screens
Hydra Flow Daily4 screens

Verdict

The call

The clearest difference is price: Periodic Timer at Free against Hydra Flow Daily's $1.99. On update cadence, ads, in-app purchases 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

Periodic Timer is free to download; Hydra Flow Daily costs $1.99 up front. Neither carries in-app purchases, so what you see is what you pay.

UpkeepUpdate frequency

Both ship on a similar rhythm, roughly every 2 months. The most recent releases landed on November 11, 2026 and November 10, 2026 respectively.

Scorecard1 real difference · 9 level
Periodic Timer versus Hydra Flow Daily: the parameters behind the verdict, then further details
ParameterPeriodic TimerHydra Flow Daily
PriceFree — better$1.99
Rating4.1 (171 ratings) — better—
Positive reviews52.1% of reviews—
Number of ratings171 — better—
Update frequencyEvery 2 monthsEvery 2 months
AdsNoNo
In-app purchasesNoNo
MonetizationFree—
DevicesiPhone, iPad, Apple WatchiPhone, iPad, Apple Watch
Requires iOS18.0 — better18.6
Further details — not scored
Size26 MB3 MB
Age rating4+4+
DeveloperVladimir KelinMohamed Shafi

Bugs and requests

Periodic Timer

Reported bugs

12 issues
  • Sound/notifications fail to trigger despite settings enabled
  • Timer cancels when phone is shaken or moved
  • Vibration doesn't work when screen is locked or off
  • App crashes on launch (especially after updates)
  • Watch app crashes or doesn't function
Show 7 more
  • Notifications inconsistent on Apple Watch
  • Timer speed inaccurate (runs too fast)
  • App won't open after deletion and reinstall
  • Upgrade popup spams every second, making app unusable
  • Heart rate monitor stays active, draining battery
  • Vibration doesn't work on silent mode
  • Watch green light stays on continuously

Requested features

15 requests
  • Adjustable sound volume and custom alert sounds
  • Customizable vibration patterns
  • Settings menu for user preferences
  • Ability to add notes/labels to timers
  • Seconds-only timer option
Show 10 more
  • Simple countdown timer (non-repeating)
  • Separate exercise and rest period intervals
  • Start timer at specific time of day
  • Disable sound option for silent vibration-only mode
  • Prevent screen lock while timer is running
  • Apple Watch vibration support
  • Seconds increment option (not just minutes)
  • Better Apple Watch complications and integration
  • Free trial period before purchase requirement
  • Disable shake-to-cancel functionality

Hydra Flow Daily

Not enough reviews yet to summarise bugs or requests.

In-app purchases

None

Periodic Timer

No in-app purchases

None

Hydra Flow Daily

No in-app purchases

Questions

Is Periodic Timer free?
Periodic Timer is free to download, with no in-app purchases.
Is Hydra Flow Daily free?
Hydra Flow Daily costs $1.99, with no in-app purchases.
Do Periodic Timer or Hydra Flow Daily have ads?
Neither Periodic Timer nor Hydra Flow Daily shows ads.
Which is updated more often, Periodic Timer or Hydra Flow Daily?
Periodic Timer ships an update every 2 months, and Hydra Flow Daily every 2 months. Most recently, Periodic Timer was updated on November 11, 2026 and Hydra Flow Daily on November 10, 2026.

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