# STRENGTH LAB vs Castra App

The clearest difference is update cadence: Castra App at weekly against STRENGTH LAB's every 6 weeks. On price, ads, in-app purchases and device support there is nothing between them.

Both are free to download. STRENGTH LAB sells 1 in-app purchase, starting at $250.00 per month and Castra App sells 4 in-app purchases, starting at $4.99 per month. Whichever you choose, the download price is not the number that matters.

STRENGTH LAB ships an update every 6 weeks, Castra App weekly. The most recent releases landed on October 19, 2026 and October 22, 2026 respectively.

## The numbers

| Metric | STRENGTH LAB | Castra App |
| --- | --- | --- |
| Price | Free | Free |
| In-app purchases | Yes | Yes |
| Ads | No | No |
| Update frequency | Every 6 weeks | **Weekly** |
| Size | 52 MB | 66 MB |
| Requires iOS | **15.0** | 16.6 |
| Devices | **iPhone, iPad, iPod** | iPhone, Apple Watch |
| Age rating | 17+ | 17+ |
| Developer | [JJB Enterprises, Inc.](https://appshunter.io/developer/1693425235) | [CASTRA APP OOD](https://appshunter.io/developer/1761241022) |

## What reviewers say

### STRENGTH LAB

[App page](https://appshunter.io/ios/app/strength-lab/id6450482627)

**Features:** macOS Compatibility

**In-app purchases (1)**

| Purchase | Price | Billing |
| --- | --- | --- |
| Monthly Coaching | $250.00 | per month |


### Castra App

[App page](https://appshunter.io/ios/app/castra-app/id6612004431)

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

**In-app purchases (4)**

| Purchase | Price | Billing |
| --- | --- | --- |
| Athlete Subscription | $4.99 | per month |
| Coach Monthly Subscription | $29.99 | per month |
| Athlete Annual Subscription | $49.99 | per year |
| Coach Yearly Subscription | $269.99 | per year |


## Frequently asked questions

### Is STRENGTH LAB free?

STRENGTH LAB is free to download, with in-app purchases available.

### Is Castra App free?

Castra App is free to download, with in-app purchases available.

### Do STRENGTH LAB or Castra App have ads?

Neither STRENGTH LAB nor Castra App shows ads.

### Which is updated more often, STRENGTH LAB or Castra App?

STRENGTH LAB ships an update every 6 weeks, and Castra App weekly. Most recently, STRENGTH LAB was updated on October 19, 2026 and Castra App on October 22, 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.*