Comparison

HRV4Training vs Periodic Timer +

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

Head to head
About

HRV4Training

Quantify stress, balance training and lifestyle, and improve performance with scientifically validated heart rate variability insights. This app accurately assesses HRV using your phone's camera or compatible devices, offering actionable interpretations for optimizing your training plan.

Highlights
  • HRV-based stress quantification
  • Training and lifestyle balance
  • Performance improvement insights
  • Camera-based HRV assessment
  • Integration with wearables
  • Training load analysis
  • VO2max and Lactate Threshold estimation
Features
Read full description

The first scientifically validated Heart Rate Variability (HRV) app. HRV4Training provides HRV based insights to help you quantify stress, better balance training and lifestyle, and improve performance. HRV4Training does not require a heart rate monitor, since it can accurately assess your HRV using the phone's camera. HRV4Training also works with Apple Watch, the Oura ring and all compatible Bluetooth SMART sensors. HRV4Training is also the first app that goes beyond simple measurements and provides insights on: 1) acute or day to day HRV changes in response to different stressors (alcohol, travel, sick days, training, menstruation, etc.) 2) long term multi-parameter trends to look at the big picture 3) correlations between physiological measurements and annotations 4) training load analysis, fitness, fatigue, readiness to perform and injury risk 5) VO2max estimation for runners linking the app to Strava or TrainingPeaks and using a heart rate monitor during their workouts 6) Training Polarization analysis (or 80/20) 7) Lactate Threshold Estimation for runners linking the app to Strava or TrainingPeaks and using a heart rate monitor during their workouts 8) Weekly and monthly summaries to track progress. All data is processed inside the app in order to provide you with actionable interpretations that can help optimizing your training plan and performance. Supported devices for the camera measurement: iPhones 5, 5S, 6, 6S, 6+, 6S+, SE, 7, 7+, 8, 8+, X, XS, XS Max, XR, 11, 11 Pro, 11 Pro Max, 12 mini, 12, 12 Pro, 12 Pro Max, 13 mini, 13, 13 Pro, 13 Pro Max, 14, 14 Plus, 14 Max, 14 Pro, 15, 15 Max, 15 Pro, 16, 16 Max, 16 Pro Currently unsupported devices for the camera measurement: iPhones 4S, iPads and iPods - These devices require a chest strap. Other features: - HRV-based advice helps you to adapt your trainings based on objective measures of recovery - TAGS: lets you tag your sleep, mental energy, muscle fatigue, stress and all other parameters that can help you understand what is influencing your physical condition and physiological stress - Works with Bluetooth SMART heart rate monitors (a Polar H7 is recommended) or simply your phone's Camera - Integrates with the Health app (writes heart rate, and sleep, read sleep time) - Configurable test (single or orthostatic, choose test duration between 1, 3 or 5 minutes) - Extracts and stores the following features while lying down and/or standing: heart rate, mean of beat-to-beat intervals (AVNN), standard deviation of beat-to-beat intervals (SDNN), square root of the mean squared difference of successive R-Rs (rMSSD), number of pairs of successive R-Rs that differ by more than 50 ms (pNN50), low frequency power (LF, 0.04-0.15 Hz), high frequency power (HF, 0.15-0.40 Hz) - Shows the PPG signal view to ensure signal quality during the test if the camera is used instead of a bluetooth SMART sensor - HRV4T Recovery Points to provide a single, straightforward metric to analyze your physical condition - Population summaries and people like you comparisons to put your data into perspective - Analysis of compliance and consistency - Data export via email or Dropbox - Integrates with TrainingPeaks, Oura, Strava and Coros HRV4Training requires to register an account with your email address, so that your data can be backed up safely and retrieved in case anything happens (app issue, changing phone, etc.). HRV4Training does not provide medical advice. It is intended for informational purposes only. Consult a medical professional before making health or lifestyle decisions. Please find an overview of the relevant scientific literature in our guide, here: https://marcoaltini.substack.com/p/the-ultimate-guide-to-heart-rate

About

Periodic Timer +

This app provides a simple, repeating interval timer that works in the background. It offers customizable sounds, vibration, and flexible output modes for various activities like fitness, cooking, and learning. The interface is designed to be minimalist and distraction-free.

Highlights
  • Repeating interval timer
  • Customizable sounds and vibration
  • Works in the background
  • Long intervals up to 99 hours
  • Multiple timer output modes
  • Shake to start functionality
Features
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Keep track of time without being distracted by the device! Simple and easy timer that repeats at your chosen interval. FEATURES - Many sounds to select + the ability to add custom ones. - Up to 4 pinned and up to 5 recent Quick Start items. - Long intervals - up to 99 hours! - Vibration, if the 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. - Flexibility and minimalism. - 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 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 oven 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: How can I add a custom sound? A: There are four ways. Choose one depending where is the sound file located. * If the sound on your Mac or PC: 1. Connect the device. 2. Open Finder and select the device. 3. Select Files in the menu. There you'll find 'Periodic +' folder. 4. Drug and drop the sound file there. * From Files app on iPhone: 1. Copy the required file. 2. Open Periodic + folder and paste it. * From another app on iPhone (like Mail): 1. Open the app where the file is located. 2. Find and touch Share button (it may have different name, for example Export). 3. In the appearing Share Sheet find the list of apps. If there is no Periodic +, touch More and enable it. 4. Now select Periodic + in the Share dialog and the sound will be imported. * And the most convenient "+" button! 1. Open Sounds tab. 2. Hit the "+" button in the "Folder" section and pick your file. Q: Alert is limited for 5 seconds! A: Go to Settings app, then Periodic + > 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. For this mode, in order to work, the app should be open. This app has a free version with limited features. 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!

Screenshots

HRV4Training4 screens
Periodic Timer +4 screens

Verdict

The call

The clearest difference is in-app purchases: HRV4Training at none against Periodic Timer +'s 3. HRV4Training also leads on update cadence (every 6 weeks vs every 4 months) and chart position (#15 vs unranked). Periodic Timer +'s advantage is price ($4.99 vs $9.99) and rating (3.9 vs 3.6). On review sentiment, ads 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

HRV4Training costs $9.99 and Periodic Timer + $4.99 up front. Periodic Timer + sells 3 one-off in-app purchases. HRV4Training asks for nothing beyond the download.

ReceptionRating · Positive reviews · Number of ratings

Periodic Timer + holds the better App Store score, 3.9 against 3.6. Both are backed by a comparable volume of ratings — 288 and 74 respectively. Written reviews complicate that: 61% of HRV4Training's written reviews are positive against 54% of Periodic Timer +'s, so the app with the better star average is not the one people write more warmly about.

UpkeepUpdate frequency

HRV4Training ships an update every 6 weeks, Periodic Timer + every 4 months. The most recent releases landed on September 27, 2026 and September 24, 2026 respectively.

Scorecard8 real differences · 3 level
HRV4Training versus Periodic Timer +: the parameters behind the verdict, then further details
ParameterHRV4TrainingPeriodic Timer +
Price$9.99$4.99 — better
Rating3.6 (288 ratings)3.9 (74 ratings) — better
Positive reviews61.1% of reviews — better53.6% of reviews
Number of ratings288 — better74
Update frequencyEvery 6 weeks — betterEvery 4 months
AdsNoNo
In-app purchasesNo — betterYes
MonetizationPaidFree — better
Best chart rank#15 — better—
DevicesiPhone, iPodiPhone, iPad, Apple Watch — better
Requires iOS15.6 — better17.0
Further details — not scored
Size35 MB12 MB
Age rating4+4+
DeveloperA.S.M.A. B.V.Vladimir Kelin

Customer experience

HRV4Training

All ratings288 ratings
Positive62.2%
Neutral5.6%
Negative32.3%
Written reviews450 reviews
Positive61.1%
Neutral7.3%
Negative31.6%

Periodic Timer +

All ratings74 ratings
Positive67.6%
Neutral9.5%
Negative23.0%
Written reviews84 reviews
Positive53.6%
Neutral14.3%
Negative32.1%

Bugs and requests

HRV4Training

Reported bugs

3 issues
  • App crashes frequently, especially with iOS updates
  • Syncing issues with Strava, TrainingPeaks, and Apple Health
  • Camera-based measurements often unreliable or inconsistent

Requested features

4 requests
  • Allow multiple measurements per day
  • Improve integration with Apple Watch and other wearables
  • Add more customization options and data visualization
  • Expand support for non-athletic use cases

Periodic Timer +

Not enough reviews yet to summarise bugs or requests.

In-app purchases

None

HRV4Training

No in-app purchases

3 purchases

Periodic Timer +

One-time3
  • Tip a Banana$0.99
  • Tip a Coffee$3.99
  • Donate: Bust the project!$9.99

Questions

Is HRV4Training free?
HRV4Training costs $9.99, with no in-app purchases.
Is Periodic Timer + free?
Periodic Timer + costs $4.99, and also offers in-app purchases.
Which has better reviews, HRV4Training or Periodic Timer +?
Periodic Timer + is rated higher. HRV4Training averages 3.6 out of 5 from 288 ratings, while Periodic Timer + averages 3.9 from 74 ratings.
Do HRV4Training or Periodic Timer + have ads?
Neither HRV4Training nor Periodic Timer + shows ads.
Which is updated more often, HRV4Training or Periodic Timer +?
HRV4Training ships an update every 6 weeks, and Periodic Timer + every 4 months. Most recently, HRV4Training was updated on September 27, 2026 and Periodic Timer + on September 24, 2026.

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