diff --git a/app/src/androidTest/java/org/kiwix/kiwixmobile/mimetype/MimeTypeTest.kt b/app/src/androidTest/java/org/kiwix/kiwixmobile/mimetype/MimeTypeTest.kt
index c2190a20b6..576bf5dbe4 100644
--- a/app/src/androidTest/java/org/kiwix/kiwixmobile/mimetype/MimeTypeTest.kt
+++ b/app/src/androidTest/java/org/kiwix/kiwixmobile/mimetype/MimeTypeTest.kt
@@ -76,6 +76,7 @@ class MimeTypeTest : BaseActivityTest() {
     }
     val zimFileReader = ZimFileReader(
       zimFile,
+      null,
       Archive(zimFile.canonicalPath),
       NightModeConfig(SharedPreferenceUtil(context), context)
     )
diff --git a/core/src/main/java/org/kiwix/kiwixmobile/core/main/AddNoteDialog.kt b/core/src/main/java/org/kiwix/kiwixmobile/core/main/AddNoteDialog.kt
index e280061a1d..5cd95a7f7e 100644
--- a/core/src/main/java/org/kiwix/kiwixmobile/core/main/AddNoteDialog.kt
+++ b/core/src/main/java/org/kiwix/kiwixmobile/core/main/AddNoteDialog.kt
@@ -117,13 +117,13 @@ class AddNoteDialog : DialogFragment() {
       .inject(this)
 
     // Returns name of the form ".../Kiwix/granbluefantasy_en_all_all_nopic_2018-10.zim"
-    zimFileName = zimReaderContainer.zimCanonicalPath
+    zimFileName = zimReaderContainer.zimCanonicalPath ?: zimReaderContainer.name
     if (zimFileName != null) { // No zim file currently opened
       zimFileTitle = zimReaderContainer.zimFileTitle
       zimId = zimReaderContainer.id.orEmpty()
 
       if (arguments != null) {
-        articleTitle = arguments?.getString(NOTES_TITLE)
+        articleTitle = arguments?.getString(NOTES_TITLE)?.substringAfter(": ")
         zimFileUrl = arguments?.getString(ARTICLE_URL).orEmpty()
       } else {
         val webView = (activity as WebViewProvider?)?.getCurrentWebView()
diff --git a/core/src/main/java/org/kiwix/kiwixmobile/core/main/CoreReaderFragment.kt b/core/src/main/java/org/kiwix/kiwixmobile/core/main/CoreReaderFragment.kt
index a579544d07..18e7236be6 100644
--- a/core/src/main/java/org/kiwix/kiwixmobile/core/main/CoreReaderFragment.kt
+++ b/core/src/main/java/org/kiwix/kiwixmobile/core/main/CoreReaderFragment.kt
@@ -26,6 +26,7 @@ import android.content.Intent
 import android.content.ServiceConnection
 import android.content.SharedPreferences
 import android.content.pm.PackageManager
+import android.content.res.AssetFileDescriptor
 import android.content.res.Configuration
 import android.graphics.Canvas
 import android.graphics.Rect
@@ -1386,13 +1387,20 @@ abstract class CoreReaderFragment :
     externalLinkOpener?.openExternalUrl(intent)
   }
 
-  protected fun openZimFile(file: File, isCustomApp: Boolean = false) {
+  protected fun openZimFile(
+    file: File?,
+    isCustomApp: Boolean = false,
+    assetFileDescriptor: AssetFileDescriptor? = null
+  ) {
     if (hasPermission(Manifest.permission.READ_EXTERNAL_STORAGE) || isCustomApp) {
-      if (file.isFileExist()) {
-        openAndSetInContainer(file)
+      if (file?.isFileExist() == true) {
+        openAndSetInContainer(file = file)
+        updateTitle()
+      } else if (assetFileDescriptor != null) {
+        openAndSetInContainer(assetFileDescriptor = assetFileDescriptor)
         updateTitle()
       } else {
-        Log.w(TAG_KIWIX, "ZIM file doesn't exist at " + file.absolutePath)
+        Log.w(TAG_KIWIX, "ZIM file doesn't exist at " + file?.absolutePath)
         requireActivity().toast(R.string.error_file_not_found, Toast.LENGTH_LONG)
       }
     } else {
@@ -1419,16 +1427,24 @@ abstract class CoreReaderFragment :
     )
   }
 
-  private fun openAndSetInContainer(file: File) {
+  private fun openAndSetInContainer(
+    file: File? = null,
+    assetFileDescriptor: AssetFileDescriptor? = null
+  ) {
     try {
-      if (isNotPreviouslyOpenZim(file.canonicalPath)) {
+      if (isNotPreviouslyOpenZim(file?.canonicalPath)) {
         webViewList.clear()
       }
     } catch (e: IOException) {
       e.printStackTrace()
     }
     zimReaderContainer?.let { zimReaderContainer ->
-      zimReaderContainer.setZimFile(file)
+      if (assetFileDescriptor != null) {
+        zimReaderContainer.setZimFileDescriptor(assetFileDescriptor)
+      } else {
+        zimReaderContainer.setZimFile(file)
+      }
+
       val zimFileReader = zimReaderContainer.zimFileReader
       zimFileReader?.let { zimFileReader ->
         // uninitialized the service worker to fix https://github.com/kiwix/kiwix-android/issues/2561
diff --git a/core/src/main/java/org/kiwix/kiwixmobile/core/main/MainRepositoryActions.kt b/core/src/main/java/org/kiwix/kiwixmobile/core/main/MainRepositoryActions.kt
index 4f6a440cc9..6acee4c889 100644
--- a/core/src/main/java/org/kiwix/kiwixmobile/core/main/MainRepositoryActions.kt
+++ b/core/src/main/java/org/kiwix/kiwixmobile/core/main/MainRepositoryActions.kt
@@ -24,6 +24,7 @@ import org.kiwix.kiwixmobile.core.di.ActivityScope
 import org.kiwix.kiwixmobile.core.page.bookmark.adapter.BookmarkItem
 import org.kiwix.kiwixmobile.core.page.history.adapter.HistoryListItem.HistoryItem
 import org.kiwix.kiwixmobile.core.page.notes.adapter.NoteListItem
+import org.kiwix.kiwixmobile.core.zim_manager.fileselect_view.adapter.BooksOnDiskListItem.BookOnDisk
 import javax.inject.Inject
 
 private const val TAG = "MainPresenter"
@@ -33,6 +34,7 @@ class MainRepositoryActions @Inject constructor(private val dataSource: DataSour
   private var saveHistoryDisposable: Disposable? = null
   private var saveBookmarkDisposable: Disposable? = null
   private var saveNoteDisposable: Disposable? = null
+  private var saveBookDisposable: Disposable? = null
   private var deleteNoteDisposable: Disposable? = null
 
   fun saveHistory(history: HistoryItem) {
@@ -61,10 +63,16 @@ class MainRepositoryActions @Inject constructor(private val dataSource: DataSour
       .subscribe({}, { e -> Log.e(TAG, "Unable to delete note", e) })
   }
 
+  fun saveBook(book: BookOnDisk) {
+    saveBookDisposable = dataSource.saveBook(book)
+      .subscribe({}, { e -> Log.e(TAG, "Unable to save book", e) })
+  }
+
   fun dispose() {
     saveHistoryDisposable?.dispose()
     saveBookmarkDisposable?.dispose()
     saveNoteDisposable?.dispose()
     deleteNoteDisposable?.dispose()
+    saveBookDisposable?.dispose()
   }
 }
diff --git a/core/src/main/java/org/kiwix/kiwixmobile/core/page/bookmark/adapter/BookmarkItem.kt b/core/src/main/java/org/kiwix/kiwixmobile/core/page/bookmark/adapter/BookmarkItem.kt
index 0f5401103b..552028020d 100644
--- a/core/src/main/java/org/kiwix/kiwixmobile/core/page/bookmark/adapter/BookmarkItem.kt
+++ b/core/src/main/java/org/kiwix/kiwixmobile/core/page/bookmark/adapter/BookmarkItem.kt
@@ -51,7 +51,7 @@ data class BookmarkItem(
   ) : this(
     zimId = zimFileReader.id,
     zimName = zimFileReader.name,
-    zimFilePath = zimFileReader.zimFile.canonicalPath,
+    zimFilePath = zimFileReader.zimFile?.canonicalPath,
     bookmarkUrl = url,
     title = title,
     favicon = zimFileReader.favicon
diff --git a/core/src/main/java/org/kiwix/kiwixmobile/core/page/history/adapter/HistoryListItem.kt b/core/src/main/java/org/kiwix/kiwixmobile/core/page/history/adapter/HistoryListItem.kt
index eee4fca52b..8556e4086e 100644
--- a/core/src/main/java/org/kiwix/kiwixmobile/core/page/history/adapter/HistoryListItem.kt
+++ b/core/src/main/java/org/kiwix/kiwixmobile/core/page/history/adapter/HistoryListItem.kt
@@ -48,7 +48,7 @@ sealed class HistoryListItem : PageRelated {
     ) : this(
       zimId = zimFileReader.id,
       zimName = zimFileReader.name,
-      zimFilePath = zimFileReader.zimFile.canonicalPath,
+      zimFilePath = zimFileReader.zimFile?.canonicalPath ?: "",
       favicon = zimFileReader.favicon,
       historyUrl = url,
       title = title,
diff --git a/core/src/main/java/org/kiwix/kiwixmobile/core/page/notes/adapter/NoteListItem.kt b/core/src/main/java/org/kiwix/kiwixmobile/core/page/notes/adapter/NoteListItem.kt
index 4f40d24cd8..1741fab2f9 100644
--- a/core/src/main/java/org/kiwix/kiwixmobile/core/page/notes/adapter/NoteListItem.kt
+++ b/core/src/main/java/org/kiwix/kiwixmobile/core/page/notes/adapter/NoteListItem.kt
@@ -35,7 +35,7 @@ data class NoteListItem(
   ) : this(
     zimId = zimFileReader.id,
     title = title,
-    zimFilePath = zimFileReader.zimFile.canonicalPath,
+    zimFilePath = zimFileReader.zimFile?.canonicalPath,
     zimUrl = url,
     favicon = zimFileReader.favicon,
     noteFilePath = noteFilePath
diff --git a/core/src/main/java/org/kiwix/kiwixmobile/core/page/notes/viewmodel/effects/ShowOpenNoteDialog.kt b/core/src/main/java/org/kiwix/kiwixmobile/core/page/notes/viewmodel/effects/ShowOpenNoteDialog.kt
index 77873906d4..8adaa9b4ae 100644
--- a/core/src/main/java/org/kiwix/kiwixmobile/core/page/notes/viewmodel/effects/ShowOpenNoteDialog.kt
+++ b/core/src/main/java/org/kiwix/kiwixmobile/core/page/notes/viewmodel/effects/ShowOpenNoteDialog.kt
@@ -45,8 +45,13 @@ data class ShowOpenNoteDialog(
       { effects.offer(OpenPage(page, zimReaderContainer)) },
       {
         val item = page as NoteListItem
-        val file = File(item.zimFilePath.orEmpty())
-        zimReaderContainer.setZimFile(file)
+        // Check if zimFilePath is not null, and then set it in zimReaderContainer.
+        // For custom apps, we are currently using fileDescriptor, and they only have a single file in them,
+        // which is already set in zimReaderContainer, so there's no need to set it again.
+        item.zimFilePath?.let {
+          val file = File(it)
+          zimReaderContainer.setZimFile(file)
+        }
         effects.offer(OpenNote(item.noteFilePath, item.zimUrl, item.title))
       }
     )
diff --git a/core/src/main/java/org/kiwix/kiwixmobile/core/reader/ZimFileReader.kt b/core/src/main/java/org/kiwix/kiwixmobile/core/reader/ZimFileReader.kt
index b8553d56e4..5a85bf35cf 100644
--- a/core/src/main/java/org/kiwix/kiwixmobile/core/reader/ZimFileReader.kt
+++ b/core/src/main/java/org/kiwix/kiwixmobile/core/reader/ZimFileReader.kt
@@ -52,13 +52,15 @@ import javax.inject.Inject
 private const val TAG = "ZimFileReader"
 
 class ZimFileReader constructor(
-  val zimFile: File,
+  val zimFile: File?,
+  val assetFileDescriptor: AssetFileDescriptor? = null,
   private val jniKiwixReader: Archive,
   private val nightModeConfig: NightModeConfig,
   private val searcher: SuggestionSearcher = SuggestionSearcher(jniKiwixReader)
 ) {
   interface Factory {
     fun create(file: File): ZimFileReader?
+    fun create(assetFileDescriptor: AssetFileDescriptor): ZimFileReader?
 
     class Impl @Inject constructor(private val nightModeConfig: NightModeConfig) :
       Factory {
@@ -76,6 +78,26 @@ class ZimFileReader constructor(
         } catch (ignore: Exception) { // for handing the error, if any zim file is corrupted
           null
         }
+
+      override fun create(assetFileDescriptor: AssetFileDescriptor): ZimFileReader? =
+        try {
+          ZimFileReader(
+            null,
+            assetFileDescriptor,
+            nightModeConfig = nightModeConfig,
+            jniKiwixReader = Archive(
+              assetFileDescriptor.parcelFileDescriptor.dup().fileDescriptor,
+              assetFileDescriptor.startOffset,
+              assetFileDescriptor.length
+            )
+          ).also {
+            Log.e(TAG, "create: with fileDescriptor")
+          }
+        } catch (ignore: JNIKiwixException) {
+          null
+        } catch (ignore: Exception) { // for handing the error, if any zim file is corrupted
+          null
+        }
     }
   }
 
@@ -289,6 +311,7 @@ class ZimFileReader constructor(
   fun dispose() {
     jniKiwixReader.dispose()
     searcher.dispose()
+    assetFileDescriptor?.parcelFileDescriptor?.detachFd()
   }
 
   @Suppress("TooGenericExceptionCaught")
diff --git a/core/src/main/java/org/kiwix/kiwixmobile/core/reader/ZimReaderContainer.kt b/core/src/main/java/org/kiwix/kiwixmobile/core/reader/ZimReaderContainer.kt
index 5c0218228a..9c7b769028 100644
--- a/core/src/main/java/org/kiwix/kiwixmobile/core/reader/ZimReaderContainer.kt
+++ b/core/src/main/java/org/kiwix/kiwixmobile/core/reader/ZimReaderContainer.kt
@@ -17,6 +17,7 @@
  */
 package org.kiwix.kiwixmobile.core.reader
 
+import android.content.res.AssetFileDescriptor
 import android.webkit.WebResourceResponse
 import org.kiwix.kiwixmobile.core.extensions.isFileExist
 import org.kiwix.kiwixmobile.core.reader.ZimFileReader.Factory
@@ -42,6 +43,13 @@ class ZimReaderContainer @Inject constructor(private val zimFileReaderFactory: F
       else null
   }
 
+  fun setZimFileDescriptor(assetFileDescriptor: AssetFileDescriptor) {
+    zimFileReader =
+      if (assetFileDescriptor.parcelFileDescriptor.dup().fileDescriptor.valid())
+        zimFileReaderFactory.create(assetFileDescriptor)
+      else null
+  }
+
   fun getPageUrlFromTitle(title: String) = zimFileReader?.getPageUrlFrom(title)
 
   fun getRandomArticleUrl() = zimFileReader?.getRandomArticleUrl()
diff --git a/core/src/main/java/org/kiwix/kiwixmobile/core/utils/files/FileUtils.kt b/core/src/main/java/org/kiwix/kiwixmobile/core/utils/files/FileUtils.kt
index 67642e208a..942ba5a100 100644
--- a/core/src/main/java/org/kiwix/kiwixmobile/core/utils/files/FileUtils.kt
+++ b/core/src/main/java/org/kiwix/kiwixmobile/core/utils/files/FileUtils.kt
@@ -29,6 +29,7 @@ import android.provider.DocumentsContract
 import android.util.Log
 import android.webkit.URLUtil
 import android.widget.Toast
+import androidx.core.content.ContextCompat
 import androidx.documentfile.provider.DocumentFile
 import kotlinx.coroutines.CoroutineScope
 import kotlinx.coroutines.Dispatchers
@@ -402,4 +403,8 @@ object FileUtils {
       null
     }
   }
+
+  @JvmStatic
+  fun getDemoFilePathForCustomApp(context: Context) =
+    "${ContextCompat.getExternalFilesDirs(context, null)[0]}/demo.zim"
 }
diff --git a/core/src/main/java/org/kiwix/kiwixmobile/core/webserver/KiwixServer.kt b/core/src/main/java/org/kiwix/kiwixmobile/core/webserver/KiwixServer.kt
index b2071029b4..5d2fef13ec 100644
--- a/core/src/main/java/org/kiwix/kiwixmobile/core/webserver/KiwixServer.kt
+++ b/core/src/main/java/org/kiwix/kiwixmobile/core/webserver/KiwixServer.kt
@@ -18,7 +18,10 @@
 
 package org.kiwix.kiwixmobile.core.webserver
 
+import android.content.Context
 import android.util.Log
+import org.kiwix.kiwixmobile.core.reader.ZimReaderContainer
+import org.kiwix.kiwixmobile.core.utils.files.FileUtils.getDemoFilePathForCustomApp
 import org.kiwix.libkiwix.Book
 import org.kiwix.libkiwix.JNIKiwixException
 import org.kiwix.libkiwix.Library
@@ -36,13 +39,32 @@ class KiwixServer @Inject constructor(
   private val jniKiwixServer: Server
 ) {
 
-  class Factory @Inject constructor() {
+  class Factory @Inject constructor(
+    private val context: Context,
+    private val zimReaderContainer: ZimReaderContainer
+  ) {
+    @Suppress("NestedBlockDepth")
     fun createKiwixServer(selectedBooksPath: ArrayList<String>): KiwixServer {
       val kiwixLibrary = Library()
       selectedBooksPath.forEach { path ->
         try {
           val book = Book().apply {
-            update(Archive(path))
+            // Determine whether to create an Archive from an asset or a file path
+            val archive = if (path == getDemoFilePathForCustomApp(context)) {
+              // For custom apps using a demo file, create an Archive with FileDescriptor
+              val assetFileDescriptor = zimReaderContainer.zimFileReader?.assetFileDescriptor
+              val startOffset = assetFileDescriptor?.startOffset ?: 0L
+              val size = assetFileDescriptor?.length ?: 0L
+              Archive(
+                assetFileDescriptor?.parcelFileDescriptor?.dup()?.fileDescriptor,
+                startOffset,
+                size
+              )
+            } else {
+              // For regular files, create an Archive from the file path
+              Archive(path)
+            }
+            update(archive)
           }
           kiwixLibrary.addBook(book)
         } catch (e: JNIKiwixException) {
diff --git a/core/src/main/java/org/kiwix/kiwixmobile/core/webserver/ZimHostFragment.kt b/core/src/main/java/org/kiwix/kiwixmobile/core/webserver/ZimHostFragment.kt
index d9f0052ccd..84f57414ed 100644
--- a/core/src/main/java/org/kiwix/kiwixmobile/core/webserver/ZimHostFragment.kt
+++ b/core/src/main/java/org/kiwix/kiwixmobile/core/webserver/ZimHostFragment.kt
@@ -49,10 +49,12 @@ import org.kiwix.kiwixmobile.core.base.BaseFragment
 import org.kiwix.kiwixmobile.core.databinding.ActivityZimHostBinding
 import org.kiwix.kiwixmobile.core.extensions.ActivityExtensions.cachedComponent
 import org.kiwix.kiwixmobile.core.extensions.ActivityExtensions.hasNotificationPermission
+import org.kiwix.kiwixmobile.core.extensions.ActivityExtensions.isCustomApp
 import org.kiwix.kiwixmobile.core.extensions.ActivityExtensions.requestNotificationPermission
 import org.kiwix.kiwixmobile.core.extensions.toast
 import org.kiwix.kiwixmobile.core.navigateToAppSettings
 import org.kiwix.kiwixmobile.core.reader.ZimFileReader
+import org.kiwix.kiwixmobile.core.reader.ZimReaderContainer
 import org.kiwix.kiwixmobile.core.utils.ConnectivityReporter
 import org.kiwix.kiwixmobile.core.utils.REQUEST_POST_NOTIFICATION_PERMISSION
 import org.kiwix.kiwixmobile.core.utils.ServerUtils
@@ -60,15 +62,15 @@ import org.kiwix.kiwixmobile.core.utils.SharedPreferenceUtil
 import org.kiwix.kiwixmobile.core.utils.dialog.AlertDialogShower
 import org.kiwix.kiwixmobile.core.utils.dialog.KiwixDialog
 import org.kiwix.kiwixmobile.core.utils.dialog.KiwixDialog.StartServer
+import org.kiwix.kiwixmobile.core.webserver.wifi_hotspot.HotspotService
+import org.kiwix.kiwixmobile.core.webserver.wifi_hotspot.HotspotService.Companion.ACTION_CHECK_IP_ADDRESS
+import org.kiwix.kiwixmobile.core.webserver.wifi_hotspot.HotspotService.Companion.ACTION_START_SERVER
+import org.kiwix.kiwixmobile.core.webserver.wifi_hotspot.HotspotService.Companion.ACTION_STOP_SERVER
 import org.kiwix.kiwixmobile.core.zim_manager.fileselect_view.SelectionMode
 import org.kiwix.kiwixmobile.core.zim_manager.fileselect_view.adapter.BookOnDiskDelegate
 import org.kiwix.kiwixmobile.core.zim_manager.fileselect_view.adapter.BooksOnDiskAdapter
 import org.kiwix.kiwixmobile.core.zim_manager.fileselect_view.adapter.BooksOnDiskListItem
 import org.kiwix.kiwixmobile.core.zim_manager.fileselect_view.adapter.BooksOnDiskListItem.BookOnDisk
-import org.kiwix.kiwixmobile.core.webserver.wifi_hotspot.HotspotService
-import org.kiwix.kiwixmobile.core.webserver.wifi_hotspot.HotspotService.Companion.ACTION_CHECK_IP_ADDRESS
-import org.kiwix.kiwixmobile.core.webserver.wifi_hotspot.HotspotService.Companion.ACTION_START_SERVER
-import org.kiwix.kiwixmobile.core.webserver.wifi_hotspot.HotspotService.Companion.ACTION_STOP_SERVER
 import javax.inject.Inject
 
 class ZimHostFragment : BaseFragment(), ZimHostCallbacks, ZimHostContract.View {
@@ -87,6 +89,9 @@ class ZimHostFragment : BaseFragment(), ZimHostCallbacks, ZimHostContract.View {
   @Inject
   lateinit var zimReaderFactory: ZimFileReader.Factory
 
+  @Inject
+  lateinit var zimReaderContainer: ZimReaderContainer
+
   private lateinit var booksAdapter: BooksOnDiskAdapter
   private lateinit var bookDelegate: BookOnDiskDelegate.BookDelegate
   private var hotspotService: HotspotService? = null
@@ -479,21 +484,19 @@ class ZimHostFragment : BaseFragment(), ZimHostCallbacks, ZimHostContract.View {
   @Suppress("NestedBlockDepth")
   override fun addBooks(books: List<BooksOnDiskListItem>) {
     // Check if this is the app module, as custom apps may have multiple package names
-    if (requireActivity().packageName == "org.kiwix.kiwixmobile") {
+    if (!requireActivity().isCustomApp()) {
       booksAdapter.items = books
     } else {
       val updatedBooksList: MutableList<BooksOnDiskListItem> = arrayListOf()
       books.forEach {
         if (it is BookOnDisk) {
-          zimReaderFactory.create(it.file)?.let { zimFileReader ->
+          zimReaderContainer.zimFileReader?.let { zimFileReader ->
             val booksOnDiskListItem =
-              (BookOnDisk(zimFileReader.zimFile, zimFileReader) as BooksOnDiskListItem)
+              (BookOnDisk(it.file, zimFileReader) as BooksOnDiskListItem)
                 .apply {
                   isSelected = true
                 }
-            updatedBooksList.add(booksOnDiskListItem).also {
-              zimFileReader.dispose()
-            }
+            updatedBooksList.add(booksOnDiskListItem)
           }
         } else {
           updatedBooksList.add(it)
diff --git a/custom/build.gradle.kts b/custom/build.gradle.kts
index 7b042594be..e743c213ab 100644
--- a/custom/build.gradle.kts
+++ b/custom/build.gradle.kts
@@ -49,6 +49,10 @@ android {
     }
   }
   assetPacks += ":install_time_asset"
+  androidResources {
+    // to not compress zim file in asset folder
+    noCompress.add("zim")
+  }
 }
 
 fun ProductFlavor.createDownloadTask(file: File): Task {
diff --git a/custom/src/main/java/org/kiwix/kiwixmobile/custom/main/CustomFileValidator.kt b/custom/src/main/java/org/kiwix/kiwixmobile/custom/main/CustomFileValidator.kt
index 73cad95ca8..c689872de0 100644
--- a/custom/src/main/java/org/kiwix/kiwixmobile/custom/main/CustomFileValidator.kt
+++ b/custom/src/main/java/org/kiwix/kiwixmobile/custom/main/CustomFileValidator.kt
@@ -20,15 +20,14 @@ package org.kiwix.kiwixmobile.custom.main
 
 import android.content.Context
 import android.content.pm.PackageManager
+import android.content.res.AssetFileDescriptor
 import android.util.Log
 import androidx.core.content.ContextCompat
-import org.kiwix.kiwixmobile.core.extensions.isFileExist
 import org.kiwix.kiwixmobile.custom.BuildConfig
 import org.kiwix.kiwixmobile.custom.main.ValidationState.HasBothFiles
 import org.kiwix.kiwixmobile.custom.main.ValidationState.HasFile
 import org.kiwix.kiwixmobile.custom.main.ValidationState.HasNothing
 import java.io.File
-import java.io.FileOutputStream
 import java.io.IOException
 import javax.inject.Inject
 
@@ -44,10 +43,10 @@ class CustomFileValidator @Inject constructor(private val context: Context) {
   private fun detectInstallationState(
     obbFiles: List<File> = obbFiles(),
     zimFiles: List<File> = zimFiles(),
-    assetFile: File? = getFileFromPlayAssetDelivery()
+    assetFileDescriptor: AssetFileDescriptor? = getAssetFileDescriptorFromPlayAssetDelivery()
   ): ValidationState {
     return when {
-      assetFile != null -> HasFile(assetFile)
+      assetFileDescriptor != null -> HasFile(null, assetFileDescriptor)
       obbFiles.isNotEmpty() && zimFiles().isNotEmpty() -> HasBothFiles(obbFiles[0], zimFiles[0])
       obbFiles.isNotEmpty() -> HasFile(obbFiles[0])
       zimFiles.isNotEmpty() -> HasFile(zimFiles[0])
@@ -55,31 +54,12 @@ class CustomFileValidator @Inject constructor(private val context: Context) {
     }
   }
 
-  @Suppress("NestedBlockDepth", "MagicNumber")
-  private fun getFileFromPlayAssetDelivery(): File? {
-    var zimFile: File? = null
+  @Suppress("MagicNumber")
+  private fun getAssetFileDescriptorFromPlayAssetDelivery(): AssetFileDescriptor? {
     try {
       val context = context.createPackageContext(context.packageName, 0)
       val assetManager = context.assets
-      val inputStream = assetManager.open(BuildConfig.PLAY_ASSET_FILE)
-      val filePath = ContextCompat.getExternalFilesDirs(context, null)[0]
-      zimFile = File(filePath, BuildConfig.PLAY_ASSET_FILE)
-      // Write zim file data if file does not exist or corrupted
-      if (!zimFile.isFileExist() || zimFile.length() == 0L) {
-        // Delete previously corrupted file
-        if (zimFile.isFileExist()) zimFile.delete()
-        zimFile.createNewFile()
-        FileOutputStream(zimFile).use { outputSteam ->
-          inputStream.use { inputStream ->
-            val buffer = ByteArray(1024)
-            var length: Int
-            while (inputStream.read(buffer).also { length = it } > 0) {
-              outputSteam.write(buffer, 0, length)
-            }
-            outputSteam.flush()
-          }
-        }
-      }
+      return assetManager.openFd(BuildConfig.PLAY_ASSET_FILE)
     } catch (packageNameNotFoundException: PackageManager.NameNotFoundException) {
       Log.w(
         "ASSET_PACKAGE_DELIVERY",
@@ -88,7 +68,7 @@ class CustomFileValidator @Inject constructor(private val context: Context) {
     } catch (ioException: IOException) {
       Log.w("ASSET_PACKAGE_DELIVERY", "Unable to copy the content of asset $ioException")
     }
-    return zimFile
+    return null
   }
 
   private fun obbFiles() = scanDirs(ContextCompat.getObbDirs(context), "obb")
@@ -124,6 +104,8 @@ class CustomFileValidator @Inject constructor(private val context: Context) {
 
 sealed class ValidationState {
   data class HasBothFiles(val obbFile: File, val zimFile: File) : ValidationState()
-  data class HasFile(val file: File) : ValidationState()
+  data class HasFile(val file: File?, val assetFileDescriptor: AssetFileDescriptor? = null) :
+    ValidationState()
+
   object HasNothing : ValidationState()
 }
diff --git a/custom/src/main/java/org/kiwix/kiwixmobile/custom/main/CustomMainActivity.kt b/custom/src/main/java/org/kiwix/kiwixmobile/custom/main/CustomMainActivity.kt
index 3c0d1fca3d..308506cb93 100644
--- a/custom/src/main/java/org/kiwix/kiwixmobile/custom/main/CustomMainActivity.kt
+++ b/custom/src/main/java/org/kiwix/kiwixmobile/custom/main/CustomMainActivity.kt
@@ -95,6 +95,16 @@ class CustomMainActivity : CoreMainActivity() {
   override fun setupDrawerToggle(toolbar: Toolbar) {
     super.setupDrawerToggle(toolbar)
     activityCustomMainBinding.drawerNavView.apply {
+      /**
+       * Hide the 'ZimHostFragment' option from the navigation menu
+       * because we are now using fd (FileDescriptor)
+       * to read the zim file from the asset folder. Currently,
+       * 'KiwixServer' is unable to host zim files via fd.
+       * This feature is temporarily hidden for custom apps.
+       * We will re-enable it for custom apps once the issue is resolved.
+       * For more info see https://github.com/kiwix/kiwix-android/pull/3516
+       */
+      menu.findItem(R.id.menu_host_books)?.isVisible = false
       setNavigationItemSelectedListener { item ->
         closeNavigationDrawer()
         onNavigationItemSelected(item)
diff --git a/custom/src/main/java/org/kiwix/kiwixmobile/custom/main/CustomReaderFragment.kt b/custom/src/main/java/org/kiwix/kiwixmobile/custom/main/CustomReaderFragment.kt
index 090bac52d5..20672ff4ee 100644
--- a/custom/src/main/java/org/kiwix/kiwixmobile/custom/main/CustomReaderFragment.kt
+++ b/custom/src/main/java/org/kiwix/kiwixmobile/custom/main/CustomReaderFragment.kt
@@ -32,6 +32,7 @@ import org.kiwix.kiwixmobile.core.base.BaseActivity
 import org.kiwix.kiwixmobile.core.base.FragmentActivityExtensions
 import org.kiwix.kiwixmobile.core.extensions.ActivityExtensions.observeNavigationResult
 import org.kiwix.kiwixmobile.core.extensions.ActivityExtensions.setupDrawerToggle
+import org.kiwix.kiwixmobile.core.extensions.isFileExist
 import org.kiwix.kiwixmobile.core.main.CoreReaderFragment
 import org.kiwix.kiwixmobile.core.main.FIND_IN_PAGE_SEARCH_STRING
 import org.kiwix.kiwixmobile.core.main.MainMenu
@@ -39,11 +40,14 @@ import org.kiwix.kiwixmobile.core.search.viewmodel.effects.SearchItemToOpen
 import org.kiwix.kiwixmobile.core.utils.LanguageUtils
 import org.kiwix.kiwixmobile.core.utils.TAG_FILE_SEARCHED
 import org.kiwix.kiwixmobile.core.utils.dialog.DialogShower
+import org.kiwix.kiwixmobile.core.utils.files.FileUtils.getDemoFilePathForCustomApp
 import org.kiwix.kiwixmobile.core.utils.titleToUrl
 import org.kiwix.kiwixmobile.core.utils.urlSuffixToParsableUrl
+import org.kiwix.kiwixmobile.core.zim_manager.fileselect_view.adapter.BooksOnDiskListItem.BookOnDisk
 import org.kiwix.kiwixmobile.custom.BuildConfig
 import org.kiwix.kiwixmobile.custom.R
 import org.kiwix.kiwixmobile.custom.customActivityComponent
+import java.io.File
 import java.util.Locale
 import javax.inject.Inject
 
@@ -143,7 +147,22 @@ class CustomReaderFragment : CoreReaderFragment() {
     customFileValidator.validate(
       onFilesFound = {
         when (it) {
-          is ValidationState.HasFile -> openZimFile(it.file, true)
+          is ValidationState.HasFile -> {
+            if (it.assetFileDescriptor != null) {
+              openZimFile(null, true, it.assetFileDescriptor)
+            } else {
+              openZimFile(it.file, true)
+            }
+            // Save book in the database to display it in `ZimHostFragment`.
+            zimReaderContainer?.zimFileReader?.let { zimFileReader ->
+              // Check if the file is not null. If the file is null,
+              // it means we have created zimFileReader with a fileDescriptor,
+              // so we create a demo file to save it in the database for display on the `ZimHostFragment`.
+              val file = it.file ?: createDemoFile()
+              val bookOnDisk = BookOnDisk(file, zimFileReader)
+              repositoryActions?.saveBook(bookOnDisk)
+            }
+          }
           is ValidationState.HasBothFiles -> {
             it.zimFile.delete()
             openZimFile(it.obbFile, true)
@@ -157,6 +176,11 @@ class CustomReaderFragment : CoreReaderFragment() {
     )
   }
 
+  private fun createDemoFile() =
+    File(getDemoFilePathForCustomApp(requireActivity())).also {
+      if (!it.isFileExist()) it.createNewFile()
+    }
+
   @Suppress("DEPRECATION")
   override fun onCreateOptionsMenu(menu: Menu, inflater: MenuInflater) {
     super.onCreateOptionsMenu(menu, inflater)