# X3 Tracker vs Undersun Fitness

The clearest difference is in-app purchases: X3 Tracker at none against Undersun Fitness's 5. X3 Tracker also leads on rating (3.3 vs 2.9) and update cadence (every 3 weeks vs every 2 months). On price, review sentiment, ratings volume and ads there is nothing between them.

Both are free to download. Undersun Fitness sells 5 in-app purchases, starting at $9.99 per month. X3 Tracker asks for nothing beyond the download.

X3 Tracker holds the better App Store score, 3.3 against 2.9. Both are backed by a comparable volume of ratings — 23 and 51 respectively. Written reviews point the same way: 38% of X3 Tracker's written reviews are positive against 34% of Undersun Fitness's.

X3 Tracker ships an update every 3 weeks, Undersun Fitness every 2 months. Both last shipped on November 3, 2026.

## The numbers

| Metric | X3 Tracker | Undersun Fitness |
| --- | --- | --- |
| Price | Free | Free |
| Rating | **[3.3 (23 ratings)](https://appshunter.io/ios/app/x3-tracker/id1468337128/reviews)** | [2.9 (51 ratings)](https://appshunter.io/ios/app/undersun-fitness/id1519951676/reviews) |
| Number of ratings | 23 | **51** |
| Positive reviews | **37.9% of reviews** | 33.6% of reviews |
| In-app purchases | **No** | Yes |
| Ads | No | No |
| Update frequency | **Every 3 weeks** | Every 2 months |
| Monetization | **Free** | Free with in-app purchases |
| Size | 67 MB | 105 MB |
| Requires iOS | 16.4 | **15.0** |
| Devices | iPhone, iPad | **iPhone, iPad, iPod** |
| Age rating | 12+ | 4+ |
| Developer | [Jaquish Biomedical Corporation](https://appshunter.io/developer/1174051341) | [Heros Life LLC](https://appshunter.io/developer/1519951678) |

## What reviewers say

### X3 Tracker

[App page](https://appshunter.io/ios/app/x3-tracker/id1468337128)

This is the official free workout tracking tool designed for the Jaquish Biomedical X3® exercise device. It helps users log and monitor their progress while using the specialized equipment.

**Highlights:** Official workout tracking, Compatible with X3 device, Free to use, Log exercise progress

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

**In-app purchases:** none


### Undersun Fitness

[App page](https://appshunter.io/ios/app/undersun-fitness/id1519951676)

Access expert-designed workout programs for all fitness levels, usable anywhere. Follow day-by-day plans with video demonstrations of proper exercise form to build muscle or lose fat.

**Highlights:** Day-by-day workout breakdown, Expert trainer guidance, Video tutorials for exercises, Build muscle or lose fat, Workout anywhere (home, gym, outdoors)

**Features:** macOS Compatibility

**In-app purchases (5)**

| Purchase | Price | Billing |
| --- | --- | --- |
| Monthly Access | $9.99 | per month |
| Yearly Access | $69.99 | per year |
| TA2 Bodyshock | $39.99 | one-time |
| TA2 Build | $59.99 | one-time |
| TA2 SIZE-ON | $59.99 | one-time |

**What reviewers like**

- 👍 Clear and concise exercise video demonstrations
- 💪 Effective workout programs with proven results
- 🎯 Convenient band-based training for travel
- 📱 User-friendly interface design
- ⏱️ Rest timer between sets

**What reviewers complain about**

- 🐛 Frequent app crashes and freezes
- 🔴 Regular server downtime and outages
- ❌ Videos fail to load or play
- 🔐 Login and authentication issues
- 📉 Loss of workout data and progress

**Reported bugs**

- App crashes between workout modules
- Videos don't load or get stuck buffering
- Password reset email links don't work
- Login credentials not recognized despite valid account
- Error 500 server errors

**Requested features**

- Ability to view previous workout data during current workout
- Edit logged reps and band selections after submission
- Landscape mode support for tablets
- Apple Watch and Apple Health integration
- Offline/downloadable content for no-internet workouts


## Frequently asked questions

### Is X3 Tracker free?

X3 Tracker is free to download, with no in-app purchases.

### Is Undersun Fitness free?

Undersun Fitness is free to download, with in-app purchases available.

### Which has better reviews, X3 Tracker or Undersun Fitness?

X3 Tracker is rated higher. X3 Tracker averages 3.3 out of 5 from 23 ratings, while Undersun Fitness averages 2.9 from 51 ratings.

### Do X3 Tracker or Undersun Fitness have ads?

Neither X3 Tracker nor Undersun Fitness shows ads.

### Which is updated more often, X3 Tracker or Undersun Fitness?

X3 Tracker ships an update every 3 weeks, and Undersun Fitness every 2 months. Most recently, X3 Tracker was updated on November 3, 2026 and Undersun Fitness on November 3, 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.*