# Neurokeys vs Castor Connect

The clearest difference is update cadence: Neurokeys at every 2 weeks against Castor Connect's every 2 months. Castor Connect's advantage is device support (3 vs 1) and iOS requirement (13.0 vs 18.2). On price, 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.

Neurokeys ships an update every 2 weeks, Castor Connect every 2 months. The most recent releases landed on October 29, 2026 and October 25, 2026 respectively.

## The numbers

| Metric | Neurokeys | Castor Connect |
| --- | --- | --- |
| Price | Free | Free |
| In-app purchases | No | No |
| Ads | No | No |
| Update frequency | **Every 2 weeks** | Every 2 months |
| Monetization | — | Free |
| Size | 186 MB | 28 MB |
| Requires iOS | 18.2 | **13.0** |
| Devices | iPhone | **iPhone, iPad, iPod** |
| Age rating | 4+ | 4+ |
| Developer | [Neurocast BV](https://appshunter.io/developer/1252625745) | [Ciwit B.V.](https://appshunter.io/developer/1009756772) |

## What reviewers say

### Neurokeys

[App page](https://appshunter.io/ios/app/neurokeys/id1436297061)

**In-app purchases:** none


### Castor Connect

[App page](https://appshunter.io/ios/app/castor-connect/id1532340302)

This app allows study participants to securely complete electronic patient-reported outcome (ePRO) questionnaires on their mobile devices. It offers offline data storage and manual syncing for flexibility. Access requires an invitation or activation code.

**Highlights:** ePRO questionnaire completion, Offline data storage, Manual data sync, Secure participant data, Native mobile application

**In-app purchases:** none


## Frequently asked questions

### Is Neurokeys free?

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

### Is Castor Connect free?

Castor Connect is free to download, with no in-app purchases.

### Do Neurokeys or Castor Connect have ads?

Neither Neurokeys nor Castor Connect shows ads.

### Which is updated more often, Neurokeys or Castor Connect?

Neurokeys ships an update every 2 weeks, and Castor Connect every 2 months. Most recently, Neurokeys was updated on October 29, 2026 and Castor Connect on October 25, 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.*