# Castle Link vs ISD Link

The clearest difference is rating: ISD Link at 2.1 against Castle Link's 1.8. On price, review sentiment, ratings volume and update cadence there is nothing between them.

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

ISD Link holds the better App Store score, 2.1 against 1.8. Both are backed by a comparable volume of ratings — 32 and 23 respectively. Written reviews point the same way: 18% of Castle Link's written reviews are positive against 21% of ISD Link's.

Castle Link ships an update monthly, ISD Link every 3 weeks. The most recent releases landed on June 13, 2026 and September 21, 2026 respectively.

## The numbers

| Metric | Castle Link | ISD Link |
| --- | --- | --- |
| Price | Free | Free |
| Rating | [1.8 (32 ratings)](https://appshunter.io/ios/app/castle-link/id1215086336/reviews) | **[2.1 (23 ratings)](https://appshunter.io/ios/app/isd-link/id1568620244/reviews)** |
| Number of ratings | **32** | 23 |
| Positive reviews | 18.2% of reviews | **21.0% of reviews** |
| In-app purchases | No | No |
| Ads | No | No |
| Update frequency | Monthly | **Every 3 weeks** |
| Monetization | Free | Free |
| Size | 39 MB | 61 MB |
| Requires iOS | **12.0** | 13.0 |
| Devices | iPhone, iPad, iPod | **iPhone, iPad, iPod, Apple Watch** |
| Age rating | 4+ | 4+ |
| Developer | [Castle Creations, Inc.](https://appshunter.io/developer/1377811229) | [深圳艾斯特创新科技有限公司](https://appshunter.io/developer/1405370693) |

## What reviewers say

### Castle Link

[App page](https://appshunter.io/ios/app/castle-link/id1215086336)

Wirelessly program and update settings for compatible electronic speed controllers and BEC devices. Save and sync profiles across devices, and access data logs without an internet connection.

**Highlights:** Wireless programming via Bluetooth, Firmware updates, Save and load custom profiles, Sync settings across iOS devices, Offline functionality, Data log viewing

**Features:** macOS Compatibility

**In-app purchases:** none


### ISD Link

[App page](https://appshunter.io/ios/app/isd-link/id1568620244)

This app allows interaction with various smart devices. It prioritizes user privacy by saving all data locally and not collecting personal information. Bluetooth is required for device scanning and connection.

**Highlights:** Smart device interaction, Local data saving, No account registration, Bluetooth connectivity, Supports numerous device models

**Features:** macOS Compatibility

**In-app purchases:** none


## Frequently asked questions

### Is Castle Link free?

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

### Is ISD Link free?

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

### Which has better reviews, Castle Link or ISD Link?

ISD Link is rated higher. Castle Link averages 1.8 out of 5 from 32 ratings, while ISD Link averages 2.1 from 23 ratings.

### Do Castle Link or ISD Link have ads?

Neither Castle Link nor ISD Link shows ads.

### Which is updated more often, Castle Link or ISD Link?

Castle Link ships an update monthly, and ISD Link every 3 weeks. Most recently, Castle Link was updated on June 13, 2026 and ISD Link 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.*