diff --git a/eco-core/core-plugin/src/main/java/com/willfp/ecoskills/EcoSkillsPlugin.java b/eco-core/core-plugin/src/main/java/com/willfp/ecoskills/EcoSkillsPlugin.java
index a86010f..83b8ac7 100644
--- a/eco-core/core-plugin/src/main/java/com/willfp/ecoskills/EcoSkillsPlugin.java
+++ b/eco-core/core-plugin/src/main/java/com/willfp/ecoskills/EcoSkillsPlugin.java
@@ -5,6 +5,7 @@ import com.willfp.eco.core.command.impl.PluginCommand;
 import com.willfp.eco.core.integrations.IntegrationLoader;
 import com.willfp.ecoskills.commands.CommandEcoskills;
 import com.willfp.ecoskills.commands.CommandSkills;
+import com.willfp.ecoskills.data.DataYml;
 import com.willfp.ecoskills.effects.Effect;
 import com.willfp.ecoskills.effects.Effects;
 import com.willfp.ecoskills.skills.Skill;
@@ -17,6 +18,7 @@ import com.willfp.ecoskills.stats.Stats;
 import com.willfp.ecoskills.stats.modifier.StatModifierListener;
 import org.bukkit.event.Listener;
 
+import java.io.IOException;
 import java.util.Arrays;
 import java.util.List;
 
@@ -26,12 +28,18 @@ public class EcoSkillsPlugin extends EcoPlugin {
      */
     private static EcoSkillsPlugin instance;
 
+    /**
+     * data.yml.
+     */
+    private final DataYml dataYml;
+
     /**
      * Internal constructor called by bukkit on plugin load.
      */
     public EcoSkillsPlugin() {
         super(0, 12205, "&#ff00ae");
         instance = this;
+        dataYml = new DataYml(this);
     }
 
     @Override
@@ -50,6 +58,24 @@ public class EcoSkillsPlugin extends EcoPlugin {
         }
     }
 
+    @Override
+    protected void handleDisable() {
+        try {
+            dataYml.save();
+        } catch (IOException e) {
+            e.printStackTrace();
+        }
+    }
+
+    /**
+     * Get data.yml.
+     *
+     * @return data.yml.
+     */
+    public DataYml getDataYml() {
+        return dataYml;
+    }
+
     /**
      * Get the instance of EcoSkills.
      *
diff --git a/eco-core/core-plugin/src/main/java/com/willfp/ecoskills/api/EcoSkillsAPI.java b/eco-core/core-plugin/src/main/java/com/willfp/ecoskills/api/EcoSkillsAPI.java
index 61bb041..ccc081d 100644
--- a/eco-core/core-plugin/src/main/java/com/willfp/ecoskills/api/EcoSkillsAPI.java
+++ b/eco-core/core-plugin/src/main/java/com/willfp/ecoskills/api/EcoSkillsAPI.java
@@ -6,6 +6,7 @@ import com.willfp.ecoskills.effects.Effect;
 import com.willfp.ecoskills.skills.Skill;
 import com.willfp.ecoskills.stats.Stat;
 import org.bukkit.NamespacedKey;
+import org.bukkit.OfflinePlayer;
 import org.bukkit.entity.Player;
 import org.bukkit.inventory.ItemStack;
 import org.jetbrains.annotations.NotNull;
@@ -21,7 +22,7 @@ public interface EcoSkillsAPI {
      * @param skill  The skill.
      * @return The level.
      */
-    int getSkillLevel(@NotNull Player player,
+    int getSkillLevel(@NotNull OfflinePlayer player,
                       @NotNull Skill skill);
 
     /**
diff --git a/eco-core/core-plugin/src/main/kotlin/com/willfp/ecoskills/EcoSkillsPlayer.kt b/eco-core/core-plugin/src/main/kotlin/com/willfp/ecoskills/EcoSkillsPlayer.kt
index d77b3bf..5f3968d 100644
--- a/eco-core/core-plugin/src/main/kotlin/com/willfp/ecoskills/EcoSkillsPlayer.kt
+++ b/eco-core/core-plugin/src/main/kotlin/com/willfp/ecoskills/EcoSkillsPlayer.kt
@@ -5,14 +5,17 @@ import com.willfp.eco.util.NumberUtils
 import com.willfp.ecoskills.api.PlayerSkillExpGainEvent
 import com.willfp.ecoskills.api.PlayerSkillLevelUpEvent
 import com.willfp.ecoskills.effects.Effect
+import com.willfp.ecoskills.effects.Effects
 import com.willfp.ecoskills.skills.Skill
 import com.willfp.ecoskills.skills.Skills
 import com.willfp.ecoskills.stats.Stat
+import com.willfp.ecoskills.stats.Stats
 import org.bukkit.Bukkit
+import org.bukkit.OfflinePlayer
 import org.bukkit.entity.Player
 import org.bukkit.persistence.PersistentDataType
 
-object PlayerPlaceholders {
+object PlayerHelper {
     init {
         PlaceholderEntry(
             "average_skill_level",
@@ -25,6 +28,8 @@ object PlayerPlaceholders {
             true
         ).register()
     }
+
+    val plugin: EcoSkillsPlugin = EcoSkillsPlugin.getInstance()
 }
 
 fun Player.getTotalSkillLevel(): Int {
@@ -65,12 +70,17 @@ fun Player.giveSkillExperience(skill: Skill, experience: Double) {
     }
 }
 
-fun Player.getSkillLevel(skill: Skill): Int {
-    return this.persistentDataContainer.getOrDefault(skill.key, PersistentDataType.INTEGER, 0)
+fun OfflinePlayer.getSkillLevel(skill: Skill): Int {
+    return if (this !is Player) {
+        PlayerHelper.plugin.dataYml.getInt("player.${this.uniqueId}.${skill.id}", 0)
+    } else {
+        this.persistentDataContainer.get(skill.key, PersistentDataType.INTEGER)
+            ?: PlayerHelper.plugin.dataYml.getInt("player.${this.uniqueId}.${skill.id}", 0)
+    }
 }
 
 fun Player.setSkillLevel(skill: Skill, level: Int) {
-    this.persistentDataContainer.set(skill.key, PersistentDataType.INTEGER, level)
+    PlayerHelper.plugin.dataYml.set("player.${this.uniqueId}.${skill.id}", level)
 }
 
 fun Player.getSkillProgressToNextLevel(skill: Skill): Double {
@@ -104,4 +114,16 @@ fun Player.getStatLevel(stat: Stat): Int {
 fun Player.setStatLevel(stat: Stat, level: Int) {
     this.persistentDataContainer.set(stat.key, PersistentDataType.INTEGER, level)
     stat.updateStatLevel(this)
+}
+
+fun Player.convertPersistentToYml() {
+    for (effect in Effects.values()) {
+        PlayerHelper.plugin.dataYml.set("player.${this.uniqueId}.${effect.id}", this.getEffectLevel(effect))
+    }
+    for (stat in Stats.values()) {
+        PlayerHelper.plugin.dataYml.set("player.${this.uniqueId}.${stat.id}", this.getStatLevel(stat))
+    }
+    for (skill in Skills.values()) {
+        PlayerHelper.plugin.dataYml.set("player.${this.uniqueId}.${skill.id}", this.getSkillLevel(skill))
+    }
 }
\ No newline at end of file
diff --git a/eco-core/core-plugin/src/main/kotlin/com/willfp/ecoskills/api/EcoSkillsAPIImpl.kt b/eco-core/core-plugin/src/main/kotlin/com/willfp/ecoskills/api/EcoSkillsAPIImpl.kt
index 360fcfc..bc3bbac 100644
--- a/eco-core/core-plugin/src/main/kotlin/com/willfp/ecoskills/api/EcoSkillsAPIImpl.kt
+++ b/eco-core/core-plugin/src/main/kotlin/com/willfp/ecoskills/api/EcoSkillsAPIImpl.kt
@@ -7,11 +7,12 @@ import com.willfp.ecoskills.effects.Effect
 import com.willfp.ecoskills.skills.Skill
 import com.willfp.ecoskills.stats.Stat
 import org.bukkit.NamespacedKey
+import org.bukkit.OfflinePlayer
 import org.bukkit.entity.Player
 import org.bukkit.inventory.ItemStack
 
 object EcoSkillsAPIImpl: EcoSkillsAPI {
-    override fun getSkillLevel(player: Player, skill: Skill): Int {
+    override fun getSkillLevel(player: OfflinePlayer, skill: Skill): Int {
         return player.getSkillLevel(skill)
     }
 
diff --git a/eco-core/core-plugin/src/main/kotlin/com/willfp/ecoskills/data/DataConversionListener.kt b/eco-core/core-plugin/src/main/kotlin/com/willfp/ecoskills/data/DataConversionListener.kt
new file mode 100644
index 0000000..6153c72
--- /dev/null
+++ b/eco-core/core-plugin/src/main/kotlin/com/willfp/ecoskills/data/DataConversionListener.kt
@@ -0,0 +1,17 @@
+package com.willfp.ecoskills.data
+
+import com.willfp.ecoskills.EcoSkillsPlugin
+import com.willfp.ecoskills.convertPersistentToYml
+import org.bukkit.event.EventHandler
+import org.bukkit.event.Listener
+import org.bukkit.event.player.PlayerJoinEvent
+import java.net.http.WebSocket
+
+class DataConversionListener(
+    private val plugin: EcoSkillsPlugin
+): Listener {
+    @EventHandler
+    fun onJoin(event: PlayerJoinEvent) {
+        event.player.convertPersistentToYml()
+    }
+}
\ No newline at end of file
diff --git a/eco-core/core-plugin/src/main/kotlin/com/willfp/ecoskills/data/DataYml.kt b/eco-core/core-plugin/src/main/kotlin/com/willfp/ecoskills/data/DataYml.kt
new file mode 100644
index 0000000..fa799f5
--- /dev/null
+++ b/eco-core/core-plugin/src/main/kotlin/com/willfp/ecoskills/data/DataYml.kt
@@ -0,0 +1,13 @@
+package com.willfp.ecoskills.data
+
+import com.willfp.eco.core.EcoPlugin
+import com.willfp.eco.core.config.yaml.YamlBaseConfig
+
+class DataYml(
+    plugin: EcoPlugin
+): YamlBaseConfig(
+    "data",
+    false,
+    plugin
+) {
+}
\ No newline at end of file