Comparison

TachyMon vs NightBell

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

Head to head
About

TachyMon

Receive immediate alerts for significant heart rate fluctuations, ideal for conditions like POTS or during exercise. Customize thresholds and receive detailed event tracking. Premium features offer advanced data visualization and reporting.

Highlights
  • Customizable heart rate threshold alerts
  • Haptic feedback for alerts
  • Real-time heart rate and average display
  • Alert event tracking and logging
  • Temporary alert silencing
  • Detailed monitoring data review
  • Shareable PDF reports (premium)
Features
Read full description

Get rapid alerts for significant heart rate changes due to POTS, tachycardia, exercise or other activities. Features: - Haptic alerts based on custom threshold levels. - Customizable upper and lower threshold levels for current heart rate and difference from recent average. - The main display shows: current heart rate, moving average of recent heart rate, and delta of current heart rate to average. - Display colors change to show severity of alert. - The app tracks alert events with start time of event, event duration, starting average heart rate, and maximum or minimum heart rate during event. - Triple tap to temporarily silence alerts. - Review detailed monitoring data on the companion iPhone app. Premium features: - View detailed heart rate chart for each event - Share event info directly from watch, or export from iPhone to Photos app - Run monitoring sessions directly on your iPhone, without an Apple Watch, by connecting a Bluetooth heart rate sensor - Generate a shareable PDF report for each session - Add notes and symptoms to Alert Events - Export Alert Event raw heart rate data to .csv - View live session data on the iPhone companion app - View a summary of Alert Events over last week / month / year TachyMon was created by the developer for his niece Alex, who was diagnosed with Postural Orthostatic Tachycardia Syndrome (POTS) in the fall of 2021. Alex was experiencing frequent fainting, and her family noticed the episodes often followed a rapid rise in her heart rate. She wanted a heads-up the moment that started happening. Alex uses TachyMon's alerts as a cue to sit or crouch down when her heart rate climbs quickly, and she finds the app helps her feel a bit more in control of her day. It is a simple but specialized app, and we hope it may help others with POTS, or anyone who wants to be alerted to changes in their heart rate. APPLE HEALTH TachyMon integrates with the Apple Health app. TachyMon stores workout information (including heart rate) with the Apple Health app. WARNING: It is important to consult with medical professionals if you are concerned about your health. The TachyMon app is intended for informational purposes only. It is not a substitute for specialized medical care. Terms of Use (EULA): https://www.apple.com/legal/internet-services/itunes/dev/stdeula/

About

NightBell

This app monitors for sleepwalking episodes using motion sensors. It triggers a gentle alarm to wake you and can alert household members. A unique task-based system on a smartwatch helps differentiate between sleepwalking and being awake to prevent false alarms.

Highlights
  • Sleepwalking detection via motion sensors
  • Gentle alarm to wake user
  • Household member alerts
  • Smartwatch task for false alarm prevention
  • Designed for sleepwalker safety
Features
Read full description

NightBell is an app developed to meet sleepwalker needs. It’s designed to keep you safe by triggering an alarm, gently waking you up, and alerting your household members, if you start sleepwalking. Key Features: 1. Sleepwalking Detection: NightBell uses motion sensors to detect sleepwalking episodes and triggers an alarm to wake you up. 2. Gentle Alarm: The app wakes you up gently, minimizing disruption while ensuring you are aware of your sleepwalking. 3. Prevention of false alarms: If NightBell detects walking when the session is active, it will ask the user to perform a simple Task on the Apple Watch to understand if he’s awake or sleepwalking. Download NightBell now and experience the peace of mind that comes with knowing you'll be alerted if sleepwalking occurs. Sleep tight and let NightBell watch over your slumber.

Screenshots

TachyMon4 screens
NightBell3 screens

Verdict

The call

The clearest difference is rating: NightBell at 5.0 against TachyMon's 3.8. NightBell also leads on review sentiment (100% vs 58%) and in-app purchases (none vs 2). TachyMon's advantage is ratings volume (287 vs 3). On price, 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

CostPrice · In-app purchases · Ads · Monetization

Both are free to download. TachyMon sells 2 in-app purchases, starting at $2.99 per month. NightBell asks for nothing beyond the download.

ReceptionRating · Positive reviews · Number of ratings

NightBell holds the better App Store score, 5.0 against 3.8. That said, the two scores are not equally well evidenced: TachyMon has 287 ratings behind it against 3, so its average is the more settled of the two. Written reviews point the same way: 58% of TachyMon's written reviews are positive against 100% of NightBell's.

UpkeepUpdate frequency

TachyMon ships an update every 3 months, NightBell every 11 days. The most recent releases landed on November 12, 2026 and November 3, 2026 respectively.

Scorecard6 real differences · 4 level
TachyMon versus NightBell: the parameters behind the verdict, then further details
ParameterTachyMonNightBell
PriceFreeFree
Rating3.8 (287 ratings)5.0 (3 ratings) — better
Positive reviews58.0% of reviews100.0% of reviews — better
Number of ratings287 — better3
Update frequencyEvery 3 monthsEvery 11 days — better
AdsNoNo
In-app purchasesYesNo — better
MonetizationFree with in-app purchasesFree — better
DevicesiPhone, Apple WatchiPhone, Apple Watch
Requires iOS16.416.0 — better
Further details — not scored
Size36 MB4 MB
Age rating9+4+
DeveloperWhip Development Inc.Irina Deeva

Customer experience

TachyMon

All ratings286 ratings
Positive69.2%
Neutral5.2%
Negative25.5%
Written reviews207 reviews
Positive58.0%
Neutral13.0%
Negative29.0%

NightBell

All ratings3 ratings
Positive100.0%
Neutral0.0%
Negative0.0%
Written reviews1 reviews
Positive100.0%
Neutral0.0%
Negative0.0%

Bugs and requests

TachyMon

Reported bugs

4 issues
  • Frequent disconnections from heart rate monitor
  • Inconsistent data sync between watch and phone
  • Inability to reinstall app on new devices
  • Freezing and crashing issues on latest updates

Requested features

5 requests
  • Add ability to log symptoms and notes
  • Implement emergency contact alerts
  • Improve data export and sharing options
  • Enhance graphing and trend analysis tools
  • Optimize battery usage and background monitoring

NightBell

Not enough reviews yet to summarise bugs or requests.

In-app purchases

2 purchases

TachyMon

Subscriptions2
  • TachyMon Premium Monthly1 Month trial$2.991 Month
  • TachyMon Premium Annual1 Month trial$19.991 Year
None

NightBell

No in-app purchases

Questions

Is TachyMon free?
TachyMon is free to download, with in-app purchases available.
Is NightBell free?
NightBell is free to download, with no in-app purchases.
Which has better reviews, TachyMon or NightBell?
NightBell is rated higher. TachyMon averages 3.8 out of 5 from 287 ratings, while NightBell averages 5.0 from 3 ratings.
Do TachyMon or NightBell have ads?
Neither TachyMon nor NightBell shows ads.
Which is updated more often, TachyMon or NightBell?
TachyMon ships an update every 3 months, and NightBell every 11 days. Most recently, TachyMon was updated on November 12, 2026 and NightBell on November 3, 2026.

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