diff --git a/eco-api/src/main/java/com/willfp/eco/core/gui/menu/Menu.java b/eco-api/src/main/java/com/willfp/eco/core/gui/menu/Menu.java
index 62a3e5cc..fddc8745 100644
--- a/eco-api/src/main/java/com/willfp/eco/core/gui/menu/Menu.java
+++ b/eco-api/src/main/java/com/willfp/eco/core/gui/menu/Menu.java
@@ -11,6 +11,7 @@ import org.jetbrains.annotations.NotNull;
 import org.jetbrains.annotations.Nullable;
 
 import java.util.List;
+import java.util.Map;
 import java.util.Set;
 
 /**
@@ -59,6 +60,37 @@ public interface Menu {
      */
     List<ItemStack> getCaptiveItems(@NotNull Player player);
 
+    /**
+     * Add state for a player.
+     *
+     * @param player The player.
+     * @param key    The key.
+     * @param value  The state.
+     */
+    void addState(@NotNull Player player,
+                  @NotNull String key,
+                  @Nullable Object value);
+
+
+    /**
+     * Get state for a player.
+     *
+     * @param player The player.
+     * @param key    The key.
+     * @param <T>    The type of state.
+     * @return The value.
+     */
+    @Nullable <T> T getState(@NotNull Player player,
+                             @NotNull String key);
+
+    /**
+     * Get state for a player.
+     *
+     * @param player The player.
+     * @return The state.
+     */
+    Map<String, Object> getState(@NotNull Player player);
+
     /**
      * Write data.
      *
@@ -68,7 +100,9 @@ public interface Menu {
      * @param value  The value.
      * @param <T>    The type.
      * @param <Z>    The type.
+     * @deprecated Use addState instead.
      */
+    @Deprecated(since = "6.35.0", forRemoval = true)
     <T, Z> void writeData(@NotNull Player player,
                           @NotNull NamespacedKey key,
                           @NotNull PersistentDataType<T, Z> type,
@@ -83,7 +117,9 @@ public interface Menu {
      * @param <T>    The type.
      * @param <Z>    The type.
      * @return The data.
+     * @deprecated Use getState instead.
      */
+    @Deprecated(since = "6.35.0", forRemoval = true)
     @Nullable <T, Z> T readData(@NotNull Player player,
                                 @NotNull NamespacedKey key,
                                 @NotNull PersistentDataType<T, Z> type);
@@ -93,7 +129,9 @@ public interface Menu {
      *
      * @param player The player.
      * @return The keys.
+     * @deprecated Use getState instead.
      */
+    @Deprecated(since = "6.35.0", forRemoval = true)
     Set<NamespacedKey> getKeys(@NotNull Player player);
 
     /**
diff --git a/eco-core/core-backend/src/main/kotlin/com/willfp/eco/internal/gui/menu/EcoMenu.kt b/eco-core/core-backend/src/main/kotlin/com/willfp/eco/internal/gui/menu/EcoMenu.kt
index 09596c96..12d0cc16 100644
--- a/eco-core/core-backend/src/main/kotlin/com/willfp/eco/internal/gui/menu/EcoMenu.kt
+++ b/eco-core/core-backend/src/main/kotlin/com/willfp/eco/internal/gui/menu/EcoMenu.kt
@@ -4,6 +4,7 @@ import com.willfp.eco.core.gui.menu.CloseHandler
 import com.willfp.eco.core.gui.menu.Menu
 import com.willfp.eco.core.gui.slot.Slot
 import com.willfp.eco.internal.gui.slot.EcoSlot
+import com.willfp.eco.util.NamespacedKeyUtils
 import org.bukkit.Bukkit
 import org.bukkit.NamespacedKey
 import org.bukkit.entity.Player
@@ -73,20 +74,30 @@ class EcoMenu(
         key: NamespacedKey,
         type: PersistentDataType<T, Z>,
         value: Z
-    ) {
-        val inventory = player.openInventory.topInventory.asRenderedInventory() ?: return
-        inventory.data[key] = value
-        inventory.render()
-    }
+    ) = addState(player, key.toString(), value)
 
-    override fun <T : Any, Z : Any> readData(player: Player, key: NamespacedKey, type: PersistentDataType<T, Z>): T? {
-        val inventory = player.openInventory.topInventory.asRenderedInventory() ?: return null
-        return inventory.data[key] as? T?
-    }
+    override fun <T : Any, Z : Any> readData(player: Player, key: NamespacedKey, type: PersistentDataType<T, Z>): T? =
+        getState(player, key.toString())
 
     override fun getKeys(player: Player): Set<NamespacedKey> {
         val inventory = player.openInventory.topInventory.asRenderedInventory() ?: return emptySet()
-        return inventory.data.keys
+        return inventory.state.keys.mapNotNull { NamespacedKeyUtils.fromStringOrNull(it) }.toSet()
+    }
+
+    override fun addState(player: Player, key: String, value: Any?) {
+        val inventory = player.openInventory.topInventory.asRenderedInventory() ?: return
+        inventory.state[key] = value
+        inventory.render()
+    }
+
+    override fun getState(player: Player): Map<String, Any?> {
+        val inventory = player.openInventory.topInventory.asRenderedInventory() ?: return emptyMap()
+        return inventory.state.toMap()
+    }
+
+    override fun <T : Any> getState(player: Player, key: String): T? {
+        val inventory = player.openInventory.topInventory.asRenderedInventory() ?: return null
+        return inventory.state[key] as? T?
     }
 
     override fun refresh(player: Player) {
diff --git a/eco-core/core-backend/src/main/kotlin/com/willfp/eco/internal/gui/menu/MenuRenderedInventory.kt b/eco-core/core-backend/src/main/kotlin/com/willfp/eco/internal/gui/menu/MenuRenderedInventory.kt
index c5adb0bc..8c6da7ff 100644
--- a/eco-core/core-backend/src/main/kotlin/com/willfp/eco/internal/gui/menu/MenuRenderedInventory.kt
+++ b/eco-core/core-backend/src/main/kotlin/com/willfp/eco/internal/gui/menu/MenuRenderedInventory.kt
@@ -1,7 +1,6 @@
 package com.willfp.eco.internal.gui.menu
 
 import com.willfp.eco.util.MenuUtils
-import org.bukkit.NamespacedKey
 import org.bukkit.entity.Player
 import org.bukkit.inventory.Inventory
 import org.bukkit.inventory.ItemStack
@@ -12,7 +11,7 @@ class MenuRenderedInventory(
     val player: Player
 ) {
     val captiveItems = mutableListOf<ItemStack>()
-    val data = mutableMapOf<NamespacedKey, Any>()
+    val state = mutableMapOf<String, Any?>()
 
     fun render() {
         generateCaptive()