# X3 Force vs Castle Flexx

The clearest difference is review sentiment: X3 Force at 70% against Castle Flexx's 19%. X3 Force also leads on rating (4.1 vs 3.0) and ads (none vs shown). Castle Flexx's advantage is in-app purchases (none vs 2). On price, ratings volume, update cadence and iOS requirement there is nothing between them.

Both are free to download. X3 Force sells 2 in-app purchases, starting at $14.99 per month. Castle Flexx asks for nothing beyond the download.

X3 Force holds the better App Store score, 4.1 against 3.0. Both are backed by a comparable volume of ratings — 20 and 32 respectively. Written reviews point the same way: 70% of X3 Force's written reviews are positive against 19% of Castle Flexx's.

X3 Force ships an update fortnightly, Castle Flexx monthly. The most recent releases landed on September 24, 2026 and September 21, 2026 respectively.

## The numbers

| Metric | X3 Force | Castle Flexx |
| --- | --- | --- |
| Price | Free | Free |
| Rating | **[4.1 (20 ratings)](https://appshunter.io/ios/app/x3-force/id1571190223/reviews)** | [3.0 (32 ratings)](https://appshunter.io/ios/app/castle-flexx/id6450963146/reviews) |
| Number of ratings | 20 | **32** |
| Positive reviews | **70.0% of reviews** | 18.8% of reviews |
| In-app purchases | Yes | **No** |
| Ads | **No** | Yes |
| Update frequency | **Fortnightly** | Monthly |
| Monetization | Free with in-app purchases | **Ad-supported** |
| Size | 26 MB | 80 MB |
| Requires iOS | **15.0** | 16.4 |
| Devices | **iPhone, iPad, iPod, Apple Watch** | iPhone |
| Age rating | 4+ | 4+ |
| Developer | [Jaquish Biomedical Corporation](https://appshunter.io/developer/1174051341) | [Castle Flexx](https://appshunter.io/developer/1695941246) |

## What reviewers say

### X3 Force

[App page](https://appshunter.io/ios/app/x3-force/id1571190223)

This application works with a smart resistance bar to track your exercise sessions in real time. It displays force data, quantifies workout quality, and helps you monitor progress to maximize results. Focus on improving your performance metrics for enhanced growth.

**Highlights:** Real-time force tracking, Quantify workout quality, Record workout duration, Monitor rep consistency, Calculate time under tension, View peak forces

**Features:** Apple Watch app, Vision Pro support

**In-app purchases (2)**

| Purchase | Price | Billing |
| --- | --- | --- |
| Monthly | $14.99 | per month |
| Yearly | $164.99 | per year |


### Castle Flexx

[App page](https://appshunter.io/ios/app/castle-flexx/id6450963146)

This app offers a simple interface to shop for award-winning devices designed to alleviate chronic pain. It also provides a training section, FlexxLab, to help users manage conditions like plantar fasciitis, back pain, and hip pain.

**Highlights:** Shop for pain relief devices, FlexxLab training section, Addresses chronic pain issues, Supports iPhone and iPod, Designed for mobility

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

**In-app purchases:** none


## Frequently asked questions

### Is X3 Force free?

X3 Force is free to download, with in-app purchases available.

### Is Castle Flexx free?

Castle Flexx is free to download, with no in-app purchases.

### Which has better reviews, X3 Force or Castle Flexx?

X3 Force is rated higher. X3 Force averages 4.1 out of 5 from 20 ratings, while Castle Flexx averages 3.0 from 32 ratings.

### Do X3 Force or Castle Flexx have ads?

Castle Flexx shows ads; X3 Force does not.

### Which is updated more often, X3 Force or Castle Flexx?

X3 Force ships an update fortnightly, and Castle Flexx monthly. Most recently, X3 Force was updated on September 24, 2026 and Castle Flexx on September 21, 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.*