Castle Link vs ISD Go
Price, ratings, monetisation and update history for both apps, side by side — with what reviewers say about each.
Castle Link
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.
- Wireless programming via Bluetooth
- Firmware updates
- Save and load custom profiles
- Sync settings across iOS devices
- Offline functionality
- Data log viewing
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The Castle Link™ app enables users to wirelessly program settings and update firmware on any current Castle Creations ESC, many older models and the BEC 2.0/BEC Pro using the waterproof Castle B•LINK Bluetooth® adapter. You can quickly alter parameters and fine-tune adjustments anytime, anywhere. - Save profiles to allow for quick changes between settings - Sync information between multiple iOS devices - No data/internet connection required - The Castle Link app can be used with multiple B•LINK adapters or can store vehicle information and allow users to use one adapter on multiple vehicles - Each B•LINK is protected with a 4-digit passcode to prevent tampering with your settings - Download and View Data Logs from compatible controllers Requirements: - Castle B•LINK Bluetooth adapter (011-0135-00)
ISD Go
Control and manage wireless smart devices with a user-friendly interface. Connect and operate devices via Bluetooth, and receive automatic firmware updates when new versions are available.
- Connect BLE smart devices
- Wireless device operation
- Automatic firmware detection
- Firmware upgrades
- User-friendly interface
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ISD GO is an APP specially used to connect Aster wireless smart devices, so as to provide users with a more convenient and user-friendly user interface to operate Aster's smart devices. We have added the following features in ISD GO: 1. Bind Esther BLE (Bluetooth Low Energy) smart device Users can bind Aster Bluetooth smart devices with their mobile phones, so that they can wirelessly access and operate the devices through their mobile phones. 2. Firmware upgrade When a new device firmware is released on the official website of Esther, ISD GO will automatically detect it, so as to realize the firmware upgrade of the smart device.
Screenshots
Verdict
The clearest difference is update cadence: ISD Go at weekly against Castle Link's monthly. On price, rating, review sentiment and ratings volume there is nothing between them.
Scored on Price · Rating · Positive reviews · Number of ratings · Update frequency · Ads · In-app purchases · Monetization · Best chart rank · Devices · Requires iOS
Both are free to download. Neither carries in-app purchases, so what you see is what you pay.
On the App Store both sit at effectively the same score — 1.8 for Castle Link against 1.8 for ISD Go. Both are backed by a comparable volume of ratings — 32 and 30 respectively. Written reviews split almost evenly too, at 18% and 19% positive.
Castle Link ships an update monthly, ISD Go weekly. The most recent releases landed on October 14, 2026 and October 20, 2026 respectively.
| Parameter | Castle Link | ISD Go |
|---|---|---|
| Price | Free | Free |
| Rating | 1.8 (32 ratings) | 1.8 (30 ratings) — better |
| Positive reviews | 18.2% of reviews | 18.5% of reviews — better |
| Number of ratings | 32 — better | 30 |
| Update frequency | Monthly | Weekly — better |
| Ads | No | No |
| In-app purchases | No | No |
| Monetization | Free | Free |
| Devices | iPhone, iPad, iPod | iPhone, iPad, iPod, Mac — better |
| Requires iOS | 12.0 | 11.0 — better |
| Further details — not scored | ||
| Size | 39 MB | 26 MB |
| Age rating | 4+ | 4+ |
| Developer | Castle Creations Inc | 深圳艾斯特创新科技有限公司 |
Customer experience
Castle Link
ISD Go
User reviews
Castle Link
From 32 App Store ratingsWhat we love
- 👍 Easy to program ESC
- 👍 Data logging is fantastic
- 👍 Save profile feature is useful
- 👍 Convenient for quick setting changes
Room to improve
- 🐛 App crashes frequently
- 🐛 App freezes often
- 🐛 Bluetooth connection issues
- 🐛 Bricks ESCs
- 🐛 Throttle curve not working
ISD Go
From 30 App Store ratingsWhat we love
- 👍 Easy firmware updates (sometimes)
- 👍 Practical app interface
- 👍 Works for some users
- 👍 Good hardware functionality (without app)
Room to improve
- 🐛 Frequent connection drops (Bluetooth)
- 🐛 Firmware update failures
- 🐛 Device not detected
- 🐛 App crashes
- 🐛 Inaccurate readings/settings
Bugs and requests
Castle Link
Reported bugs
16 issues- App crashes on passcode entry
- App freezes
- Bluetooth connection problems
- Bricking ESCs
- Throttle curve not working
Show 11 moreShow fewer
- Demo mode not functional
- Torque settings not saving
- Motor test not selectable
- Data logging issues
- Latest update causing problems
- Incompatibility with newer products
- Loading screen stuck
- Locking out ESC and beeping
- ESC not recognized by app
- Lost connection to ESC
- Firmware update failure
Requested features
9 requests- Add data logging to iOS app
- Allow viewing data logs on phone
- Fix throttle curve interface
- Add Android application
- Make motor test selectable
Show 4 moreShow fewer
- Fix data logging history clearing
- Allow firmware updates via app
- Support for newer ESCs (e.g., Copperhead)
- Allow app to work with cables
ISD Go
Reported bugs
56 issues- App crashes during updates
- Device not recognized by app
- Abnormal network connection for firmware server
- App not updated for current iOS
- Bluetooth not reconnecting
Show 51 moreShow fewer
- Inaccurate current readings
- Device disconnected during update
- No device detected
- App corrupts N series chargers
- Batteries showing incorrect discharge status
- Unable to bind to FD-200
- Bluetooth will not connect
- Computer doesn't recognize charger
- App fails to download firmware
- Drag brake not engaging
- ESC not staying connected via Bluetooth
- Timeout messages
- CM1620: inaccurate battery/power display, cut-off info
- A8 Air not seen via USB or Bluetooth
- Unstable firmware update connection
- FD200: impossible to discharge below 3.0V, limited current options, preset conflicts
- N16 recognized as N8
- App shows 'Waiting for device'
- Bluetooth drops all the time
- Does not work on iOS 16.5
- Shows wrong device (N8 instead of 16N)
- Firmware version mismatch
- K4 locked on 'UPDATE' screen
- FD-200 disconnects during discharge
- FD-200 keeps discharging regardless of parameters
- App disconnects and won't reconnect
- FD200 Bluetooth disconnects all the time
- CM1620: unstable Bluetooth, incorrect charge level display
- App does not stay connected via Bluetooth
- ESC70: times out, loses connection, resets to factory settings
- FD-200 drops Bluetooth signal
- Bluetooth dropping constantly
- App loses connection to FD200
- H605 Air error code
- New version doesn't work with H605
- App crashes constantly
- App does not remember cut off voltage
- App loses binding to device
- Fails to connect to FD-200
- Difficulty re-establishing BT connection
- K4 won't connect
- Cannot connect to FD-200
- Bluetooth connection problem
- App doesn't find FD-200
- Bluetooth connection with iPad not working
- Cannot connect with iPad or Android
- H605 Air overvolts battery packs
- Incapable of balance charge
- Font size too big on iPhone SE
- Cell voltage not displayed correctly after update
- Manual calibration doesn't work
Requested features
13 requests- Update app for current iOS
- Fix firmware update issues
- Improve Bluetooth connection stability
- Allow discharging to lower voltages (e.g., 0.0V)
- Increase discharge current options
Show 8 moreShow fewer
- Fix preset conflicts
- Improve drag brake settings
- Add dark mode
- Add balance charge option
- Improve font size for smaller screens
- Allow landscape mode on iPad
- Add charge volume in %
- Add alarm for charged battery
In-app purchases
Castle Link
No in-app purchases
ISD Go
No in-app purchases
