How to Install Castle APK on Firestick (4K, 4K Max, Lite): 2026

Castle APK runs on every Amazon Firestick model (Firestick 4K, Firestick 4K Max and Firestick Lite), because Fire TV is built on Android. The app is not in the Amazon Appstore, so you install it by sideloading it with the Downloader app. The steps below are the same on all three models.

The genuine app is version v2.1.3 and the file is 36 MB. Check both numbers after downloading. If they do not match, delete the file and download again from the Castle APK download page.

Before You Start

• Connect your Firestick to stable Wi-Fi.
• Free up some space: the file is 36 MB, and the app needs room for cache while streaming.
• Download only from the official homepage. Other sites may offer altered or outdated copies.

Step 1: Allow Unknown Sources

1. From the Firestick home screen, go to Settings > My Fire TV > Developer Options.
2. Select Install Unknown Apps, then turn it On for Downloader.
3. If you do not see Developer Options, go to Settings > My Fire TV > About and select your Firestick name seven times until Developer Options appears.

Step 2: Install the Downloader App

1. From the home screen, open Find > Search and search for Downloader.
2. Install the Downloader app from the Amazon Appstore and open it.
3. Allow Downloader to access your media and files when it asks.

Step 3: Download Castle APK

1. Open Downloader and select the URL box.
2. Enter the download link shown on the Castle APK homepage and select Go.
3. Wait for the file to download, then check that it is version v2.1.3 and 36 MB.
4. When asked, select Install, then Open once the install finishes.

Step 4: Use Mouse Toggle for Easier Navigation

Castle APK is designed for touch screens, so some buttons and menus are hard to reach with the Firestick remote alone. Mouse Toggle fixes this:

1. Install Mouse Toggle for Fire TV from the Amazon Appstore.
2. Open Mouse Toggle and turn it on.
3. While using Castle APK, press the Play/Pause button on your remote to switch the mouse pointer on and off, and use the directional ring to move it.

Firestick Storage Tips

• Firestick Lite and older models have limited storage. Uninstall apps you no longer use before installing Castle APK.
• Firestick 4K Max has more storage and handles the app more comfortably, but the same storage rules still apply.
• Clear the app cache if streams start buffering: go to Settings > Applications > Manage Installed Applications > Castle APK > Clear Cache. Clearing cache does not delete the app.
• Do not fill the storage completely. A full Firestick slows down, and streams may stutter or fail to load.

If the Install Fails

• Check that Unknown Sources is turned on for Downloader (Step 1).
• Check that you have enough free space, then try again.
• If the download stops partway, delete the partial file and download again. An incomplete file will not install, and its size will not match 36 MB.
• Restart your Firestick and retry if the installer freezes.

For the full setup walkthrough, see our Castle APK setup guide. Castle APK also works on Android TV sets and boxes. See Castle APK for Android TV and the Castle APK for TV page.