diff --git a/api/src/main/java/com/velocitypowered/api/event/connection/ConnectionHandshakeEvent.java b/api/src/main/java/com/velocitypowered/api/event/connection/ConnectionHandshakeEvent.java
index f2ecc0547..a590a83ad 100644
--- a/api/src/main/java/com/velocitypowered/api/event/connection/ConnectionHandshakeEvent.java
+++ b/api/src/main/java/com/velocitypowered/api/event/connection/ConnectionHandshakeEvent.java
@@ -7,7 +7,7 @@ import org.checkerframework.checker.nullness.qual.NonNull;
 /**
  * This event is fired when a handshake is established between a client and Velocity.
  */
-public class ConnectionHandshakeEvent {
+public final class ConnectionHandshakeEvent {
     private final @NonNull InboundConnection connection;
 
     public ConnectionHandshakeEvent(@NonNull InboundConnection connection) {
diff --git a/api/src/main/java/com/velocitypowered/api/event/connection/DisconnectEvent.java b/api/src/main/java/com/velocitypowered/api/event/connection/DisconnectEvent.java
index 0ef43909b..5a861dd51 100644
--- a/api/src/main/java/com/velocitypowered/api/event/connection/DisconnectEvent.java
+++ b/api/src/main/java/com/velocitypowered/api/event/connection/DisconnectEvent.java
@@ -8,7 +8,7 @@ import org.checkerframework.checker.nullness.qual.NonNull;
  * This event is fired when a player disconnects from the proxy. Operations on the provided player, aside from basic
  * data retrieval operations, may behave in undefined ways.
  */
-public class DisconnectEvent {
+public final class DisconnectEvent {
     private @NonNull final Player player;
 
     public DisconnectEvent(@NonNull Player player) {
diff --git a/api/src/main/java/com/velocitypowered/api/event/connection/LoginEvent.java b/api/src/main/java/com/velocitypowered/api/event/connection/LoginEvent.java
index 0ac7f9374..fa19da77e 100644
--- a/api/src/main/java/com/velocitypowered/api/event/connection/LoginEvent.java
+++ b/api/src/main/java/com/velocitypowered/api/event/connection/LoginEvent.java
@@ -8,7 +8,7 @@ import org.checkerframework.checker.nullness.qual.NonNull;
 /**
  * This event is fired once the player has been authenticated but before they connect to a server on the proxy.
  */
-public class LoginEvent implements ResultedEvent<ResultedEvent.ComponentResult> {
+public final class LoginEvent implements ResultedEvent<ResultedEvent.ComponentResult> {
     private final Player player;
     private ComponentResult result;
 
diff --git a/api/src/main/java/com/velocitypowered/api/event/connection/PluginMessageEvent.java b/api/src/main/java/com/velocitypowered/api/event/connection/PluginMessageEvent.java
index b16f933e4..4b2941a94 100644
--- a/api/src/main/java/com/velocitypowered/api/event/connection/PluginMessageEvent.java
+++ b/api/src/main/java/com/velocitypowered/api/event/connection/PluginMessageEvent.java
@@ -15,7 +15,7 @@ import java.util.Arrays;
  * This event is fired when a plugin message is sent to the proxy, either from a client ({@link com.velocitypowered.api.proxy.Player})
  * or a server ({@link com.velocitypowered.api.proxy.ServerConnection}).
  */
-public class PluginMessageEvent implements ResultedEvent<PluginMessageEvent.ForwardResult> {
+public final class PluginMessageEvent implements ResultedEvent<PluginMessageEvent.ForwardResult> {
     private final ChannelMessageSource source;
     private final ChannelMessageSink target;
     private final ChannelIdentifier identifier;
@@ -74,7 +74,7 @@ public class PluginMessageEvent implements ResultedEvent<PluginMessageEvent.Forw
     /**
      * A result determining whether or not to forward this message on.
      */
-    public static class ForwardResult implements ResultedEvent.Result {
+    public static final class ForwardResult implements ResultedEvent.Result {
         private static final ForwardResult ALLOWED = new ForwardResult(true);
         private static final ForwardResult DENIED = new ForwardResult(false);
 
diff --git a/api/src/main/java/com/velocitypowered/api/event/connection/PostLoginEvent.java b/api/src/main/java/com/velocitypowered/api/event/connection/PostLoginEvent.java
index 7ecc23bbc..653259f5f 100644
--- a/api/src/main/java/com/velocitypowered/api/event/connection/PostLoginEvent.java
+++ b/api/src/main/java/com/velocitypowered/api/event/connection/PostLoginEvent.java
@@ -7,7 +7,7 @@ import com.velocitypowered.api.proxy.Player;
  * This event is fired once the player has been successfully authenticated and
  * fully initialized and player will be connected to server after this event
  */
-public class PostLoginEvent {
+public final class PostLoginEvent {
 
     private final Player player;
 
diff --git a/api/src/main/java/com/velocitypowered/api/event/connection/PreLoginEvent.java b/api/src/main/java/com/velocitypowered/api/event/connection/PreLoginEvent.java
index d5e817f49..f6b8c8e70 100644
--- a/api/src/main/java/com/velocitypowered/api/event/connection/PreLoginEvent.java
+++ b/api/src/main/java/com/velocitypowered/api/event/connection/PreLoginEvent.java
@@ -14,7 +14,7 @@ import java.util.Optional;
  * This event is fired when a player has initiated a connection with the proxy but before the proxy authenticates the
  * player with Mojang or before the player's proxy connection is fully established (for offline mode).
  */
-public class PreLoginEvent implements ResultedEvent<PreLoginEvent.PreLoginComponentResult> {
+public final class PreLoginEvent implements ResultedEvent<PreLoginEvent.PreLoginComponentResult> {
     private final InboundConnection connection;
     private final String username;
     private PreLoginComponentResult result;
@@ -55,7 +55,7 @@ public class PreLoginEvent implements ResultedEvent<PreLoginEvent.PreLoginCompon
     /**
      * Represents an "allowed/allowed with forced online\offline mode/denied" result with a reason allowed for denial.
      */
-    public static class PreLoginComponentResult implements ResultedEvent.Result {
+    public static final class PreLoginComponentResult implements ResultedEvent.Result {
 
         private static final PreLoginComponentResult ALLOWED = new PreLoginComponentResult(Result.ALLOWED, null);
         private static final PreLoginComponentResult FORCE_ONLINEMODE = new PreLoginComponentResult(Result.FORCE_ONLINE, null);
diff --git a/api/src/main/java/com/velocitypowered/api/event/permission/PermissionsSetupEvent.java b/api/src/main/java/com/velocitypowered/api/event/permission/PermissionsSetupEvent.java
index de3976025..f10e8fdd6 100644
--- a/api/src/main/java/com/velocitypowered/api/event/permission/PermissionsSetupEvent.java
+++ b/api/src/main/java/com/velocitypowered/api/event/permission/PermissionsSetupEvent.java
@@ -12,7 +12,7 @@ import org.checkerframework.checker.nullness.qual.Nullable;
  *
  * <p>This event is only called once per subject, on initialisation.</p>
  */
-public class PermissionsSetupEvent {
+public final class PermissionsSetupEvent {
     private final PermissionSubject subject;
     private final PermissionProvider defaultProvider;
     private PermissionProvider provider;
diff --git a/api/src/main/java/com/velocitypowered/api/event/player/GameProfileRequestEvent.java b/api/src/main/java/com/velocitypowered/api/event/player/GameProfileRequestEvent.java
index ab46c37c1..aec8e445d 100644
--- a/api/src/main/java/com/velocitypowered/api/event/player/GameProfileRequestEvent.java
+++ b/api/src/main/java/com/velocitypowered/api/event/player/GameProfileRequestEvent.java
@@ -9,7 +9,7 @@ import org.checkerframework.checker.nullness.qual.Nullable;
  * This event is fired after the {@link com.velocitypowered.api.event.connection.PreLoginEvent} in order to set up the
  * game profile for the user. This can be used to configure a custom profile for a user, i.e. skin replacement.
  */
-public class GameProfileRequestEvent {
+public final class GameProfileRequestEvent {
     private final String username;
     private final InboundConnection connection;
     private final GameProfile originalProfile;
diff --git a/api/src/main/java/com/velocitypowered/api/event/player/KickedFromServerEvent.java b/api/src/main/java/com/velocitypowered/api/event/player/KickedFromServerEvent.java
index bfdf296e6..c24ec0c58 100644
--- a/api/src/main/java/com/velocitypowered/api/event/player/KickedFromServerEvent.java
+++ b/api/src/main/java/com/velocitypowered/api/event/player/KickedFromServerEvent.java
@@ -11,7 +11,7 @@ import org.checkerframework.checker.nullness.qual.NonNull;
  * Fired when a player is kicked from a server. You may either allow Velocity to kick the player (with an optional reason
  * override) or redirect the player to a separate server.
  */
-public class KickedFromServerEvent implements ResultedEvent<KickedFromServerEvent.ServerKickResult> {
+public final class KickedFromServerEvent implements ResultedEvent<KickedFromServerEvent.ServerKickResult> {
     private final Player player;
     private final RegisteredServer server;
     private final Component originalReason;
@@ -60,7 +60,7 @@ public class KickedFromServerEvent implements ResultedEvent<KickedFromServerEven
     /**
      * Tells the proxy to disconnect the player with the specified reason.
      */
-    public static class DisconnectPlayer implements ServerKickResult {
+    public static final class DisconnectPlayer implements ServerKickResult {
         private final Component component;
 
         private DisconnectPlayer(Component component) {
@@ -90,7 +90,7 @@ public class KickedFromServerEvent implements ResultedEvent<KickedFromServerEven
      * Tells the proxy to redirect the player to another server. No messages will be sent from the proxy
      * when this result is used.
      */
-    public static class RedirectPlayer implements ServerKickResult {
+    public static final class RedirectPlayer implements ServerKickResult {
         private final RegisteredServer server;
 
         private RedirectPlayer(RegisteredServer server) {
diff --git a/api/src/main/java/com/velocitypowered/api/event/player/PlayerChatEvent.java b/api/src/main/java/com/velocitypowered/api/event/player/PlayerChatEvent.java
index 6df36fb98..7bf64b542 100644
--- a/api/src/main/java/com/velocitypowered/api/event/player/PlayerChatEvent.java
+++ b/api/src/main/java/com/velocitypowered/api/event/player/PlayerChatEvent.java
@@ -11,7 +11,7 @@ import java.util.Optional;
 /**
  * This event is fired once the player has been authenticated but before they connect to a server on the proxy.
  */
-public class PlayerChatEvent implements ResultedEvent<PlayerChatEvent.ChatResult> {
+public final class PlayerChatEvent implements ResultedEvent<PlayerChatEvent.ChatResult> {
     private final Player player;
     private final String message;
     private ChatResult result;
@@ -52,7 +52,7 @@ public class PlayerChatEvent implements ResultedEvent<PlayerChatEvent.ChatResult
     /**
      * Represents the result of the {@link PlayerChatEvent}.
      */
-    public static class ChatResult implements ResultedEvent.Result {
+    public static final class ChatResult implements ResultedEvent.Result {
         private static final ChatResult ALLOWED = new ChatResult(true, null);
         private static final ChatResult DENIED = new ChatResult(false, null);
 
diff --git a/api/src/main/java/com/velocitypowered/api/event/player/PlayerSettingsChangedEvent.java b/api/src/main/java/com/velocitypowered/api/event/player/PlayerSettingsChangedEvent.java
index b59c643ff..f56ed5e3a 100644
--- a/api/src/main/java/com/velocitypowered/api/event/player/PlayerSettingsChangedEvent.java
+++ b/api/src/main/java/com/velocitypowered/api/event/player/PlayerSettingsChangedEvent.java
@@ -4,7 +4,7 @@ import com.google.common.base.Preconditions;
 import com.velocitypowered.api.proxy.Player;
 import com.velocitypowered.api.proxy.player.PlayerSettings;
 
-public class PlayerSettingsChangedEvent {
+public final class PlayerSettingsChangedEvent {
     private final Player player;
     private final PlayerSettings playerSettings;
 
diff --git a/api/src/main/java/com/velocitypowered/api/event/player/ServerConnectedEvent.java b/api/src/main/java/com/velocitypowered/api/event/player/ServerConnectedEvent.java
index d9115a9ea..33db0878f 100644
--- a/api/src/main/java/com/velocitypowered/api/event/player/ServerConnectedEvent.java
+++ b/api/src/main/java/com/velocitypowered/api/event/player/ServerConnectedEvent.java
@@ -8,7 +8,7 @@ import com.velocitypowered.api.proxy.server.RegisteredServer;
  * This event is fired once the player has successfully connected to the target server and the connection to the previous
  * server has been de-established.
  */
-public class ServerConnectedEvent {
+public final class ServerConnectedEvent {
     private final Player player;
     private final RegisteredServer server;
 
diff --git a/api/src/main/java/com/velocitypowered/api/event/player/ServerPreConnectEvent.java b/api/src/main/java/com/velocitypowered/api/event/player/ServerPreConnectEvent.java
index f80d3cb33..06b688f04 100644
--- a/api/src/main/java/com/velocitypowered/api/event/player/ServerPreConnectEvent.java
+++ b/api/src/main/java/com/velocitypowered/api/event/player/ServerPreConnectEvent.java
@@ -12,7 +12,7 @@ import java.util.Optional;
 /**
  * This event is fired before the player connects to a server.
  */
-public class ServerPreConnectEvent implements ResultedEvent<ServerPreConnectEvent.ServerResult> {
+public final class ServerPreConnectEvent implements ResultedEvent<ServerPreConnectEvent.ServerResult> {
     private final Player player;
     private final RegisteredServer originalServer;
     private ServerResult result;
diff --git a/api/src/main/java/com/velocitypowered/api/event/proxy/ProxyInitializeEvent.java b/api/src/main/java/com/velocitypowered/api/event/proxy/ProxyInitializeEvent.java
index 14bee8b1e..ea55e9515 100644
--- a/api/src/main/java/com/velocitypowered/api/event/proxy/ProxyInitializeEvent.java
+++ b/api/src/main/java/com/velocitypowered/api/event/proxy/ProxyInitializeEvent.java
@@ -3,7 +3,7 @@ package com.velocitypowered.api.event.proxy;
 /**
  * This event is fired by the proxy after plugins have been loaded but before the proxy starts accepting connections.
  */
-public class ProxyInitializeEvent {
+public final class ProxyInitializeEvent {
     @Override
     public String toString() {
         return "ProxyInitializeEvent";
diff --git a/api/src/main/java/com/velocitypowered/api/event/proxy/ProxyPingEvent.java b/api/src/main/java/com/velocitypowered/api/event/proxy/ProxyPingEvent.java
index e40d810b9..aa8b605b3 100644
--- a/api/src/main/java/com/velocitypowered/api/event/proxy/ProxyPingEvent.java
+++ b/api/src/main/java/com/velocitypowered/api/event/proxy/ProxyPingEvent.java
@@ -7,7 +7,7 @@ import com.velocitypowered.api.proxy.server.ServerPing;
 /**
  * This event is fired when a server list ping request is sent by a remote client.
  */
-public class ProxyPingEvent {
+public final class ProxyPingEvent {
     private final InboundConnection connection;
     private ServerPing ping;
 
diff --git a/api/src/main/java/com/velocitypowered/api/event/proxy/ProxyShutdownEvent.java b/api/src/main/java/com/velocitypowered/api/event/proxy/ProxyShutdownEvent.java
index 0ae15f192..76bfac5e7 100644
--- a/api/src/main/java/com/velocitypowered/api/event/proxy/ProxyShutdownEvent.java
+++ b/api/src/main/java/com/velocitypowered/api/event/proxy/ProxyShutdownEvent.java
@@ -4,7 +4,7 @@ package com.velocitypowered.api.event.proxy;
  * This event is fired by the proxy after the proxy has stopped accepting connections but before the proxy process
  * exits.
  */
-public class ProxyShutdownEvent {
+public final class ProxyShutdownEvent {
     @Override
     public String toString() {
         return "ProxyShutdownEvent";
diff --git a/api/src/main/java/com/velocitypowered/api/proxy/player/SkinParts.java b/api/src/main/java/com/velocitypowered/api/proxy/player/SkinParts.java
index 29a6a501e..fcd43c2c5 100644
--- a/api/src/main/java/com/velocitypowered/api/proxy/player/SkinParts.java
+++ b/api/src/main/java/com/velocitypowered/api/proxy/player/SkinParts.java
@@ -1,8 +1,6 @@
 package com.velocitypowered.api.proxy.player;
 
-public class SkinParts {
-
-    static final SkinParts SKIN_SHOW_ALL = new SkinParts((byte) 127);
+public final class SkinParts {
     private final byte bitmask;
 
     public SkinParts(byte skinBitmask) {
diff --git a/api/src/main/java/com/velocitypowered/api/proxy/server/ServerPing.java b/api/src/main/java/com/velocitypowered/api/proxy/server/ServerPing.java
index f4fb7c1ae..4ffaa83a1 100644
--- a/api/src/main/java/com/velocitypowered/api/proxy/server/ServerPing.java
+++ b/api/src/main/java/com/velocitypowered/api/proxy/server/ServerPing.java
@@ -11,7 +11,7 @@ import java.util.*;
 /**
  * Represents a 1.7 and above server list ping response. This class is immutable.
  */
-public class ServerPing {
+public final class ServerPing {
     private final Version version;
     private final Players players;
     private final Component description;
@@ -87,7 +87,7 @@ public class ServerPing {
     /**
      * A builder for {@link ServerPing} objects.
      */
-    public static class Builder {
+    public static final class Builder {
         private Version version;
         private int onlinePlayers;
         private int maximumPlayers;
@@ -217,7 +217,7 @@ public class ServerPing {
         }
     }
 
-    public static class Version {
+    public static final class Version {
         private final int protocol;
         private final String name;
 
@@ -243,7 +243,7 @@ public class ServerPing {
         }
     }
 
-    public static class Players {
+    public static final class Players {
         private final int online;
         private final int max;
         private final List<SamplePlayer> sample;
@@ -276,7 +276,7 @@ public class ServerPing {
         }
     }
 
-    public static class SamplePlayer {
+    public static final class SamplePlayer {
         private final String name;
         private final UUID id;
 
@@ -302,7 +302,7 @@ public class ServerPing {
         }
     }
 
-    public static class ModInfo {
+    public static final class ModInfo {
         public static final ModInfo DEFAULT = new ModInfo("FML", ImmutableList.of());
 
         private final String type;
@@ -322,7 +322,7 @@ public class ServerPing {
         }
     }
 
-    public static class Mod {
+    public static final class Mod {
         private final String id;
         private final String version;
 
diff --git a/api/src/main/java/com/velocitypowered/api/util/UuidUtils.java b/api/src/main/java/com/velocitypowered/api/util/UuidUtils.java
index a6c89b9cd..9cec7f6c4 100644
--- a/api/src/main/java/com/velocitypowered/api/util/UuidUtils.java
+++ b/api/src/main/java/com/velocitypowered/api/util/UuidUtils.java
@@ -10,7 +10,7 @@ import java.util.UUID;
 /**
  * Provides a small, useful selection of utilities for working with Minecraft UUIDs.
  */
-public class UuidUtils {
+public final class UuidUtils {
     private UuidUtils() {
         throw new AssertionError();
     }
diff --git a/api/src/main/java/com/velocitypowered/api/util/title/TextTitle.java b/api/src/main/java/com/velocitypowered/api/util/title/TextTitle.java
index 53a84fe45..6a3ffd0e5 100644
--- a/api/src/main/java/com/velocitypowered/api/util/title/TextTitle.java
+++ b/api/src/main/java/com/velocitypowered/api/util/title/TextTitle.java
@@ -10,7 +10,7 @@ import java.util.Optional;
 /**
  * Represents a "full" title, including all components. This class is immutable.
  */
-public class TextTitle implements Title {
+public final class TextTitle implements Title {
     private final Component title;
     private final Component subtitle;
     private final int stay;
diff --git a/api/src/main/java/com/velocitypowered/api/util/title/Titles.java b/api/src/main/java/com/velocitypowered/api/util/title/Titles.java
index 242a04411..9474b575f 100644
--- a/api/src/main/java/com/velocitypowered/api/util/title/Titles.java
+++ b/api/src/main/java/com/velocitypowered/api/util/title/Titles.java
@@ -3,7 +3,7 @@ package com.velocitypowered.api.util.title;
 /**
  * Provides special-purpose titles.
  */
-public class Titles {
+public final class Titles {
     private Titles() {
         throw new AssertionError();
     }