HRV4Biofeedback vs Diary!?
Price, ratings, monetisation and update history for both apps, side by side — with what reviewers say about each.
HRV4Biofeedback
This app uses your phone's camera to measure heart rate variability and provide biofeedback. It guides you through deep breathing exercises to improve self-regulation and manage stress. Track your progress and explore correlations with your daily experiences.
- Camera-based HRV measurement
- Real-time heart rate feedback
- Resonant frequency analysis
- Biofeedback score
- Subjective annotations
- HealthKit integration
- Bluetooth sensor support
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Improve self-regulation and better cope with stress using HRV4Biofeedback, the camera-based Heart Rate Variability (HRV) Biofeedback app APP FEATURES: > camera-based biofeedback measurement showing real-time heart rate > spot check measurements at rest > frequency power spectrum > biofeedback score to quantify the effectiveness of the practice in terms of deep breathing and duration > resonant frequency analysis to determine the optimal breathing rate for your sessions > semi-real time HRV analysis > alternative manual breathing rate configuration between 4.5 and 8.5 breaths / minute > subjective annotations, including up to 5 personalized questions > current streak > explore correlations between subjective annotations and biofeedback data > Integration with HealthKit (you can write heart rate, HRV and Mindful minutes) > weekly and monthly summaries > support for Bluetooth sensors > background nature sounds > vibration to guide you through the practice WHAT'S BIOFEEDBACK? Heart Rate Variability (HRV) Biofeedback is a technique that can directly affect physiological and psychological factors through deep breathing exercises and is an ideal strategy to help us self-regulate and better cope with stressful situations Practically speaking, HRV Biofeedback consists of providing an individual with real-time feedback on instantaneous heart rate and respiration changes while being instructed to breathe at low frequencies You can learn more about the psychological and physiological benefits of deep breathing and HRV Biofeedback, at HRV4Biofeedback.com HOW CAN I BENEFIT FROM BIOFEEDBACK? Life can be demanding, from both a physical and psychological point of view Our health and performance can be affected by how we are able to effectively cope with stressful situations and deal with anxiety, or in broader terms, our ability to emotionally self-regulate is key The goal of HRV Biofeedback is to improve self-regulation, therefore impacting positively our health and performance LEARN MORE: - App features: https://www.hrv4biofeedback.com/faq.html - An introduction to biofeedback: https://www.hrv4biofeedback.com/blog/a-primer-on-heart-rate-variability-biofeedback - How to use the camera measurement: https://www.hrv4biofeedback.com/blog/guidelines-and-best-practices-for-camera-based-measurements Supported devices for the camera measurement: iPhones 8 and onwards HRV4Biofeedback 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.) The validation of the camera-based heart rate measurement is available here: https://www.researchgate.net/publication/315059917_Comparison_of_Heart_Rate_Variability_Recording_With_Smart_Phone_Photoplethysmographic_Polar_H7_Chest_Strap_and_Electrocardiogram_Methods
Diary!?
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Urnle is a semi-private journal for the thoughts you cannot fit into a post. Express yourself in text, photos, links, audio, or video— reflect in conversations with Gurnle - or invite a friendly human guide from somewhere else on Earth. Urnle begins as a spacious private journal. Guidance is a layer you can turn toward later—not a demand placed on every thought, and never an audience you have to perform for. GurnleAI offers insights on Urnle entries by default, and human guidance is available only when you choose to invite it. You remain in control of what is shared. 1) Write, speak, photograph, film, or save the links shaping your thinking. 2) Guidance insights stay connected to the entry, so the original moment remains the source of truth. 3) Look back across ordinary days, difficult seasons, and the patterns between them. Gurnle is Urnle’s AI reflection companion. Use Gurnle as a chat partner, have a back and forth conversation, then save that conversation in your journal with your other entries. Gurnle is here for reflection—not diagnosis, therapy, or instructions for how to live. Terms of Use (EULA): https://www.apple.com/legal/internet-services/itunes/dev/stdeula/ Additional Terms of Use: https://urnle.com/terms-of-use Privacy Policy: https://urnle.com/privacy-policy
Screenshots
Verdict
The clearest difference is price: Diary!? at Free against HRV4Biofeedback's $9.99. Diary!? also leads on update cadence (every 2 days vs every 2 months). HRV4Biofeedback's advantage is in-app purchases (none vs 1) and chart position (#44 vs unranked). On ads, 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
Diary!? is free to download; HRV4Biofeedback costs $9.99 up front. Diary!? sells 1 in-app purchase, starting at $4.99 per month. HRV4Biofeedback asks for nothing beyond the download.
HRV4Biofeedback ships an update every 2 months, Diary!? every 2 days. The most recent releases landed on October 13, 2026 and October 5, 2026 respectively.
| Parameter | HRV4Biofeedback | Diary!? |
|---|---|---|
| Price | $9.99 | Free — better |
| Rating | 3.4 (29 ratings) — better | — |
| Positive reviews | 53.1% of reviews | — |
| Number of ratings | 29 — better | — |
| Update frequency | Every 2 months | Every 2 days — better |
| Ads | No | No |
| In-app purchases | No — better | Yes |
| Monetization | Free | — |
| Best chart rank | #44 — better | — |
| Devices | iPhone, iPod | iPhone, iPad, iPod — better |
| Requires iOS | 15.6 | 15.6 |
| Further details — not scored | ||
| Size | 138 MB | 28 MB |
| Age rating | 4+ | 17+ |
| Developer | A.S.M.A. B.V. | The Boggler Inc. |
In-app purchases
HRV4Biofeedback
No in-app purchases
Diary!?
- AI Guide Monthly$4.991 Month









