# Frontier X vs CORE Thermal Sensor

The clearest difference is review sentiment: Frontier X at 82% against CORE Thermal Sensor's 16%. Frontier X also leads on rating (4.6 vs 2.5) and update cadence (every 3 weeks vs every 2 months). CORE Thermal Sensor's advantage is in-app purchases (none vs 2). On price, ads, device support and iOS requirement there is nothing between them.

Both are free to download. Frontier X sells 2 in-app purchases, starting at $14.99 per month. CORE Thermal Sensor asks for nothing beyond the download.

Frontier X holds the better App Store score, 4.6 against 2.5. That said, the two scores are not equally well evidenced: Frontier X has 317 ratings behind it against 35, so its average is the more settled of the two. Written reviews point the same way: 82% of Frontier X's written reviews are positive against 16% of CORE Thermal Sensor's.

Frontier X ships an update every 3 weeks, CORE Thermal Sensor every 2 months. The most recent releases landed on September 25, 2026 and September 23, 2026 respectively.

## The numbers

| Metric | Frontier X | CORE Thermal Sensor |
| --- | --- | --- |
| Price | Free | Free |
| Rating | **[4.6 (317 ratings)](https://appshunter.io/ios/app/frontier-x/id1483444499/reviews)** | [2.5 (35 ratings)](https://appshunter.io/ios/app/core-thermal-sensor/id1521866309/reviews) |
| Number of ratings | **317** | 35 |
| Positive reviews | **81.8% of reviews** | 15.6% of reviews |
| In-app purchases | Yes | **No** |
| Ads | No | No |
| Update frequency | **Every 3 weeks** | Every 2 months |
| Monetization | Free with in-app purchases | **Free** |
| Size | 571 MB | 55 MB |
| Requires iOS | 16.0 | **15.1** |
| Devices | iPhone, Apple Watch | **iPhone, iPad, iPod** |
| Age rating | 4+ | 4+ |
| Developer | [Fourthfrontier](https://appshunter.io/developer/1331846764) | [greenteg AG](https://appshunter.io/developer/1510577388) |

## What reviewers say

### Frontier X

[App page](https://appshunter.io/ios/app/frontier-x/id1483444499)

Track your heart health and exercise performance with a smart chest strap monitor. Gain detailed insights into heart rate, rhythms, and training load. Receive personalized feedback and alerts to optimize your workouts and understand your body better.

**Highlights:** Heart Health Monitoring, Real-time Heart Rate & HRV, Breathing Rate & Strain Tracking, Activity Recording (24hrs), Personalized Vibration Alerts, AI-enabled Training Insights, Metabolic Profile Analytics (Premium)

**Features:** Apple Watch app

**In-app purchases (2)**

| Purchase | Price | Billing |
| --- | --- | --- |
| Monthly | $14.99 | per month |
| Yearly | $119.99 | per year |

**What reviewers like**

- 🚀 Amazing device
- 👍 Great HR data and insight
- 👍 Helpful in gaining more data
- 👍 Fantastic concept with excellent execution
- 👍 Loads of useful information

**What reviewers complain about**

- 🐛 Worse and worse as time goes by
- 🐛 ECG doesn't work
- 🐛 Chest strap issues, device keeps popping out
- 🐛 Paywalled functionality
- 🐛 Syncing issues, device keeps disconnecting

**Reported bugs**

- ECG stopped working
- Inaccurate breathing rate and other metrics
- Inability to edit activity details for indoor workouts
- Syncing issues with Garmin devices after firmware updates

**Requested features**

- Add interval markers
- Improve integration with Apple Fitness/Fitness+
- Add support for ANT+
- Improve compatibility with other fitness apps and devices
- Add more customization options for workouts


### CORE Thermal Sensor

[App page](https://appshunter.io/ios/app/core-thermal-sensor/id1521866309)

This app continuously monitors your core body temperature and thermal strain, providing critical data for heat training and optimal race performance. It helps athletes of all levels improve their training and achieve better results.

**Highlights:** Continuous core body temperature monitoring, Real-time Heat Strain Index, Heat Zones for training and racing, Heat Training Load and Adaptation Score, Passive heat training tracking, Data trends and historical analysis, Connectivity with sports devices

**Features:** macOS Compatibility, Vision Pro support

**In-app purchases:** none


## Frequently asked questions

### Is Frontier X free?

Frontier X is free to download, with in-app purchases available.

### Is CORE Thermal Sensor free?

CORE Thermal Sensor is free to download, with no in-app purchases.

### Which has better reviews, Frontier X or CORE Thermal Sensor?

Frontier X is rated higher. Frontier X averages 4.6 out of 5 from 317 ratings, while CORE Thermal Sensor averages 2.5 from 35 ratings.

### Do Frontier X or CORE Thermal Sensor have ads?

Neither Frontier X nor CORE Thermal Sensor shows ads.

### Which is updated more often, Frontier X or CORE Thermal Sensor?

Frontier X ships an update every 3 weeks, and CORE Thermal Sensor every 2 months. Most recently, Frontier X was updated on September 25, 2026 and CORE Thermal Sensor on September 23, 2026.

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*Compared by [AppsHunter](https://appshunter.io/) from daily US App Store data. Review summaries are generated from verbatim App Store reviews.*