# Joint Active Systems vs Quell Flex

The clearest difference is iOS requirement: Joint Active Systems at 12.4 against Quell Flex's 16.6. On price, update cadence, ads and in-app purchases there is nothing between them.

Both are free to download. Neither carries in-app purchases, so what you see is what you pay.

Joint Active Systems ships an update every 33 months, Quell Flex every 35 months. The most recent releases landed on January 1, 2026 and September 27, 2026 respectively.

## The numbers

| Metric | Joint Active Systems | Quell Flex |
| --- | --- | --- |
| Price | Free | Free |
| In-app purchases | No | No |
| Ads | No | No |
| Update frequency | **Every 33 months** | Every 35 months |
| Size | 2 MB | 23 MB |
| Requires iOS | **12.4** | 16.6 |
| Devices | **iPhone, iPod** | iPhone |
| Age rating | 4+ | 12+ |
| Developer | [Bonutti Technologies](https://appshunter.io/developer/911384806) | [NeuroMetrix, Inc.](https://appshunter.io/developer/972079953) |

## What reviewers say

### Joint Active Systems

[App page](https://appshunter.io/ios/app/joint-active-systems/id1086503051)

**Features:** macOS Compatibility

**In-app purchases:** none


### Quell Flex

[App page](https://appshunter.io/ios/app/quell-flex/id1507976263)

**Features:** macOS Compatibility

**In-app purchases:** none


## Frequently asked questions

### Is Joint Active Systems free?

Joint Active Systems is free to download, with no in-app purchases.

### Is Quell Flex free?

Quell Flex is free to download, with no in-app purchases.

### Do Joint Active Systems or Quell Flex have ads?

Neither Joint Active Systems nor Quell Flex shows ads.

### Which is updated more often, Joint Active Systems or Quell Flex?

Joint Active Systems ships an update every 33 months, and Quell Flex every 35 months. Most recently, Joint Active Systems was updated on January 1, 2026 and Quell Flex on September 27, 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.*