diff --git a/auth/.js/src/main/scala/io/udash/auth/AuthApplication.scala b/auth/.js/src/main/scala/io/udash/auth/AuthApplication.scala
index 0ecb4bfa7..2e68ad25a 100644
--- a/auth/.js/src/main/scala/io/udash/auth/AuthApplication.scala
+++ b/auth/.js/src/main/scala/io/udash/auth/AuthApplication.scala
@@ -3,7 +3,9 @@ package io.udash.auth
 import io.udash._
 
 object AuthApplication {
-  implicit class ApplicationAuthExt[HierarchyRoot >: Null <: GState[HierarchyRoot]](val application: Application[HierarchyRoot]) extends AnyVal {
+  implicit final class ApplicationAuthExt[HierarchyRoot >: Null <: GState[HierarchyRoot]](
+    private val application: Application[HierarchyRoot]
+  ) extends AnyVal {
     /**
       * Adds the default listener of authorization failure in routing (redirects to provided state).
       *
diff --git a/auth/src/main/scala/io/udash/auth/Permission.scala b/auth/src/main/scala/io/udash/auth/Permission.scala
index ac03395da..b768b4410 100644
--- a/auth/src/main/scala/io/udash/auth/Permission.scala
+++ b/auth/src/main/scala/io/udash/auth/Permission.scala
@@ -20,7 +20,7 @@ trait Permission {
 
 object Permission {
   /** Single permission as a combinator resolved implicitly. */
-  implicit class Single(private val permission: Permission) extends AnyVal with PermissionCombinator {
+  implicit final class Single(private val permission: Permission) extends AnyVal with PermissionCombinator {
     override def check(ctx: UserCtx): Boolean =
       ctx.has(permission)
 
diff --git a/auth/src/main/scala/io/udash/auth/PermissionId.scala b/auth/src/main/scala/io/udash/auth/PermissionId.scala
index b26fe3328..f495389a8 100644
--- a/auth/src/main/scala/io/udash/auth/PermissionId.scala
+++ b/auth/src/main/scala/io/udash/auth/PermissionId.scala
@@ -3,5 +3,5 @@ package io.udash.auth
 import com.avsystem.commons.serialization.{HasGenCodec, transparent}
 
 @transparent
-case class PermissionId(value: String) extends AnyVal
+final case class PermissionId(value: String) extends AnyVal
 object PermissionId extends HasGenCodec[PermissionId]
diff --git a/auth/src/main/scala/io/udash/auth/exceptions.scala b/auth/src/main/scala/io/udash/auth/exceptions.scala
index 59b2612b2..6a3554c4c 100644
--- a/auth/src/main/scala/io/udash/auth/exceptions.scala
+++ b/auth/src/main/scala/io/udash/auth/exceptions.scala
@@ -1,9 +1,5 @@
 package io.udash.auth
 
-import com.avsystem.commons.serialization.HasGenCodec
+class UnauthenticatedException extends RuntimeException(s"User has to be authenticated to access this content.")
 
-case class UnauthenticatedException() extends RuntimeException(s"User has to be authenticated to access this content.")
-object UnauthenticatedException extends HasGenCodec[UnauthenticatedException]
-
-case class UnauthorizedException() extends RuntimeException(s"Provided user context does not have access to this content.")
-object UnauthorizedException extends HasGenCodec[UnauthorizedException]
+class UnauthorizedException extends RuntimeException(s"Provided user context does not have access to this content.")
diff --git a/benchmarks/.js/src/main/scala/io/udash/benchmarks/properties/PropertyParameters.scala b/benchmarks/.js/src/main/scala/io/udash/benchmarks/properties/PropertyParameters.scala
index 78645cf1b..d7b034143 100644
--- a/benchmarks/.js/src/main/scala/io/udash/benchmarks/properties/PropertyParameters.scala
+++ b/benchmarks/.js/src/main/scala/io/udash/benchmarks/properties/PropertyParameters.scala
@@ -6,7 +6,7 @@ import japgolly.scalajs.benchmark.gui._
 import scalatags.JsDom.all._
 
 object PropertyParameters {
-  case class Entity(i: Int, s: String, r: Entity)
+  final case class Entity(i: Int, s: String, r: Entity)
   object Entity extends HasModelPropertyCreator[Entity]
 
   private def listenProperty(p: ReadableProperty[String]) = {
diff --git a/bootstrap4/.js/src/main/scala/io/udash/bootstrap/carousel/UdashCarousel.scala b/bootstrap4/.js/src/main/scala/io/udash/bootstrap/carousel/UdashCarousel.scala
index 87fa13818..2d0e8f702 100644
--- a/bootstrap4/.js/src/main/scala/io/udash/bootstrap/carousel/UdashCarousel.scala
+++ b/bootstrap4/.js/src/main/scala/io/udash/bootstrap/carousel/UdashCarousel.scala
@@ -254,7 +254,7 @@ object UdashCarousel {
     * @param keyboard Should the carousel react to keyboard events.
     * @param active   Should the animation be active.
     */
-  case class AnimationOptions(
+  final case class AnimationOptions(
     interval: Duration = 5 seconds, pause: PauseOption = PauseOption.Hover, wrap: Boolean = true,
     keyboard: Boolean = true, active: Boolean = true
   ) {
@@ -285,7 +285,7 @@ object UdashCarousel {
   * @param imgSrc  Slide image source url.
   * @param caption Slide caption content.
   */
-case class UdashCarouselSlide(imgSrc: Url)(caption: Modifier*) {
+final case class UdashCarouselSlide(imgSrc: Url)(caption: Modifier*) {
   import io.udash.css.CssView._
 
   lazy val render: Node = {
@@ -296,4 +296,4 @@ case class UdashCarouselSlide(imgSrc: Url)(caption: Modifier*) {
       )
     ).render
   }
-}
\ No newline at end of file
+}
diff --git a/bootstrap4/.js/src/main/scala/io/udash/bootstrap/dropdown/UdashDropdown.scala b/bootstrap4/.js/src/main/scala/io/udash/bootstrap/dropdown/UdashDropdown.scala
index f3246b3f1..cd38843b3 100644
--- a/bootstrap4/.js/src/main/scala/io/udash/bootstrap/dropdown/UdashDropdown.scala
+++ b/bootstrap4/.js/src/main/scala/io/udash/bootstrap/dropdown/UdashDropdown.scala
@@ -133,13 +133,13 @@ object UdashDropdown {
   /** Default dropdown elements. */
   sealed trait DefaultDropdownItem extends AbstractCase
   object DefaultDropdownItem {
-    case class Text(text: String) extends DefaultDropdownItem
-    case class Link(title: String, url: Url) extends DefaultDropdownItem
-    case class Button(title: String, clickCallback: () => Any) extends DefaultDropdownItem
-    case class Header(title: String) extends DefaultDropdownItem
-    case class Disabled(item: DefaultDropdownItem) extends DefaultDropdownItem
-    case class Raw(element: Element) extends DefaultDropdownItem
-    case class Dynamic(factory: Binding.NestedInterceptor => Element) extends DefaultDropdownItem
+    final case class Text(text: String) extends DefaultDropdownItem
+    final case class Link(title: String, url: Url) extends DefaultDropdownItem
+    final case class Button(title: String, clickCallback: () => Any) extends DefaultDropdownItem
+    final case class Header(title: String) extends DefaultDropdownItem
+    final case class Disabled(item: DefaultDropdownItem) extends DefaultDropdownItem
+    final case class Raw(element: Element) extends DefaultDropdownItem
+    final case class Dynamic(factory: Binding.NestedInterceptor => Element) extends DefaultDropdownItem
     case object Divider extends DefaultDropdownItem
   }
 
diff --git a/core/.js/src/main/scala/io/udash/bindings/Bindings.scala b/core/.js/src/main/scala/io/udash/bindings/Bindings.scala
index 6516295ac..7a4ee5548 100644
--- a/core/.js/src/main/scala/io/udash/bindings/Bindings.scala
+++ b/core/.js/src/main/scala/io/udash/bindings/Bindings.scala
@@ -1,14 +1,15 @@
 package io.udash.bindings
 
-import com.avsystem.commons._
+import com.avsystem.commons.*
 import io.udash.bindings.Bindings.{AttrOps, AttrPairOps, HasCssName, PropertyOps}
-import io.udash.bindings.modifiers._
+import io.udash.bindings.modifiers.*
 import io.udash.properties.seq.ReadableSeqProperty
 import io.udash.properties.single.ReadableProperty
-import org.scalajs.dom._
+import org.scalajs.dom.*
 import scalatags.JsDom
 import scalatags.generic.{Attr, AttrPair, AttrValue, Modifier}
 
+import scala.annotation.nowarn
 import scala.scalajs.js
 
 trait Bindings {
@@ -28,6 +29,7 @@ trait Bindings {
 
   implicit def seqFromNode(el: Node): Seq[Node] = Seq(el)
   implicit def seqFromElement(el: Element): Seq[Element] = Seq(el)
+  @nowarn("msg=Implicit parameters")
   implicit def seqNodeFromOpt[T](el: Opt[T])(implicit ev: T => Modifier[Element]): Modifier[Element] =
     new JsDom.all.SeqNode(el.toSeq)
 
diff --git a/core/.js/src/main/scala/io/udash/bindings/modifiers/package.scala b/core/.js/src/main/scala/io/udash/bindings/modifiers/package.scala
index f7317399f..98f36da0b 100644
--- a/core/.js/src/main/scala/io/udash/bindings/modifiers/package.scala
+++ b/core/.js/src/main/scala/io/udash/bindings/modifiers/package.scala
@@ -3,7 +3,7 @@ package io.udash.bindings
 import org.scalajs.dom.Node
 
 package object modifiers {
-  implicit class ElementExts(private val el: Node) extends AnyVal {
+  implicit final class ElementExts(private val el: Node) extends AnyVal {
     def replaceChildren(oldChildren: Seq[Node], newChildren: Seq[Node]): Unit = {
       if (oldChildren == null || oldChildren.isEmpty) newChildren.foreach(el.appendChild)
       else {
diff --git a/core/.js/src/main/scala/io/udash/core/Definitions.scala b/core/.js/src/main/scala/io/udash/core/Definitions.scala
index 781734e76..84852577a 100644
--- a/core/.js/src/main/scala/io/udash/core/Definitions.scala
+++ b/core/.js/src/main/scala/io/udash/core/Definitions.scala
@@ -7,7 +7,7 @@ import scalatags.generic.Modifier
 /**
   * Url wrapper - just for avoiding strings.
   */
-case class Url(value: String) extends AnyVal
+final case class Url(value: String) extends AnyVal
 object Url extends HasModelPropertyCreator[Url]
 
 /**
diff --git a/core/.js/src/test/scala/io/udash/testing/TestState.scala b/core/.js/src/test/scala/io/udash/testing/TestState.scala
index 72bfa3a74..2f6d4cf14 100644
--- a/core/.js/src/test/scala/io/udash/testing/TestState.scala
+++ b/core/.js/src/test/scala/io/udash/testing/TestState.scala
@@ -8,8 +8,8 @@ sealed abstract class TestState(val parentState: Option[ContainerTestState]) ext
 sealed abstract class ContainerTestState(parentState: Option[ContainerTestState]) extends TestState(parentState)
 sealed abstract class FinalTestState(parentState: Option[ContainerTestState]) extends TestState(parentState)
 
-case class RootState(sth: Option[Int]) extends ContainerTestState(None)
-case class ClassState(arg: String, arg2: Int) extends FinalTestState(Some(RootState(None)))
+final case class RootState(sth: Option[Int]) extends ContainerTestState(None)
+final case class ClassState(arg: String, arg2: Int) extends FinalTestState(Some(RootState(None)))
 case object ObjectState extends ContainerTestState(Some(RootState(None)))
 case object ThrowExceptionState extends ContainerTestState(Some(RootState(None)))
 case object NextObjectState extends FinalTestState(Some(ObjectState))
diff --git a/core/.js/src/test/scala/manual/PropertyErrorManualTest.scala b/core/.js/src/test/scala/manual/PropertyErrorManualTest.scala
index 05155d63d..3fc7d9c4c 100644
--- a/core/.js/src/test/scala/manual/PropertyErrorManualTest.scala
+++ b/core/.js/src/test/scala/manual/PropertyErrorManualTest.scala
@@ -58,7 +58,7 @@ object PropertyErrorManualTest {
   trait B {
     def c: Seq[C]
   }
-  case class C(d: D)
+  final case class C(d: D)
   trait D {
     def errorField: ClassicClass
   }
diff --git a/core/src/main/scala/io/udash/properties/Properties.scala b/core/src/main/scala/io/udash/properties/Properties.scala
index 30ab67302..08aa43ae0 100644
--- a/core/src/main/scala/io/udash/properties/Properties.scala
+++ b/core/src/main/scala/io/udash/properties/Properties.scala
@@ -31,20 +31,20 @@ trait Properties {
 }
 
 object Properties extends Properties {
-  class Any2Property[A] private[properties](private val value: A) extends AnyVal {
+  final class Any2Property[A] private[properties](private val value: A) extends AnyVal {
     def toProperty[B >: A : PropertyCreator]: ReadableProperty[B] = PropertyCreator[B].newImmutableProperty(value)
     def toModelProperty[B >: A : ModelPropertyCreator]: ReadableModelProperty[B] = ModelPropertyCreator[B].newImmutableProperty(value)
   }
 
-  class Any2SeqProperty[A] private[properties](private val value: Seq[A]) extends AnyVal {
+  final class Any2SeqProperty[A] private[properties](private val value: Seq[A]) extends AnyVal {
     def toSeqProperty: ReadableSeqProperty[A] = new ImmutableSeqProperty[A, Seq](value)
   }
 
-  class PropertySeq2SeqProperty[A] private[properties](private val value: ISeq[ReadableProperty[A]]) extends AnyVal {
+  final class PropertySeq2SeqProperty[A] private[properties](private val value: ISeq[ReadableProperty[A]]) extends AnyVal {
     def combineToSeqProperty: ReadableSeqProperty[A] = new PropertySeqCombinedReadableSeqProperty[A](value)
   }
 
-  class BooleanPropertyOps private[properties](private val underlying: Property[Boolean]) extends AnyVal {
+  final class BooleanPropertyOps private[properties](private val underlying: Property[Boolean]) extends AnyVal {
     /** Toggles the value of the underlying boolean-backed property.
       * @param force If true, the value change listeners will be fired even if value didn't change.
       * */
diff --git a/core/src/test/scala/io/udash/properties/BlankTest.scala b/core/src/test/scala/io/udash/properties/BlankTest.scala
index 47467aec7..26510d69f 100644
--- a/core/src/test/scala/io/udash/properties/BlankTest.scala
+++ b/core/src/test/scala/io/udash/properties/BlankTest.scala
@@ -33,7 +33,7 @@ class BlankTest extends UdashCoreTest {
 }
 
 object BlankTest {
-  case class Entity(i: Int, s: String)
+  final case class Entity(i: Int, s: String)
   object Entity extends HasModelPropertyCreator[Entity] {
     implicit val default: Blank[Entity] = Blank.Simple(Entity(5, "asd"))
   }
diff --git a/core/src/test/scala/io/udash/properties/HasGenCodecAndModelPropertyCreatorTest.scala b/core/src/test/scala/io/udash/properties/HasGenCodecAndModelPropertyCreatorTest.scala
index 7ed7dbf67..f49a011c9 100644
--- a/core/src/test/scala/io/udash/properties/HasGenCodecAndModelPropertyCreatorTest.scala
+++ b/core/src/test/scala/io/udash/properties/HasGenCodecAndModelPropertyCreatorTest.scala
@@ -24,6 +24,6 @@ class HasGenCodecAndModelPropertyCreatorTest extends UdashCoreTest {
 }
 
 object HasGenCodecAndModelPropertyCreatorTest {
-  case class Entity(i: Int, s: String, e: Option[Entity])
+  final case class Entity(i: Int, s: String, e: Option[Entity])
   object Entity extends HasGenCodecAndModelPropertyCreator[Entity]
 }
diff --git a/core/src/test/scala/io/udash/properties/ImmutablePropertyTest.scala b/core/src/test/scala/io/udash/properties/ImmutablePropertyTest.scala
index 3190867bb..5c002d9b4 100644
--- a/core/src/test/scala/io/udash/properties/ImmutablePropertyTest.scala
+++ b/core/src/test/scala/io/udash/properties/ImmutablePropertyTest.scala
@@ -150,9 +150,9 @@ class ImmutablePropertyTest extends UdashCoreTest {
 }
 
 object ImmutablePropertyTest {
-  case class Nested(s: Nested)
+  final case class Nested(s: Nested)
   object Nested extends HasModelPropertyCreator[Nested]
 
-  case class ModelEntity(s: String, i: Seq[Int], v: Vector[Int], m: ModelEntity)
+  final case class ModelEntity(s: String, i: Seq[Int], v: Vector[Int], m: ModelEntity)
   object ModelEntity extends HasModelPropertyCreator[ModelEntity]
 }
\ No newline at end of file
diff --git a/core/src/test/scala/io/udash/properties/PropertyTest.scala b/core/src/test/scala/io/udash/properties/PropertyTest.scala
index 4287652a7..803776652 100644
--- a/core/src/test/scala/io/udash/properties/PropertyTest.scala
+++ b/core/src/test/scala/io/udash/properties/PropertyTest.scala
@@ -1436,7 +1436,7 @@ class PropertyTest extends UdashCoreTest {
 }
 
 private object ReqModels {
-  case class Simple(i: Int, s: Simple)
+  final case class Simple(i: Int, s: Simple)
   object Simple extends HasModelPropertyCreator[Simple]
 
   trait ReqT {
@@ -1444,6 +1444,6 @@ private object ReqModels {
   }
   object ReqT extends HasModelPropertyCreator[ReqT]
 
-  case class SimpleSeq(i: Seq[SimpleSeq], s: SimpleSeq)
+  final case class SimpleSeq(i: Seq[SimpleSeq], s: SimpleSeq)
   object SimpleSeq extends HasModelPropertyCreator[SimpleSeq]
 }
diff --git a/css/src/main/scala/io/udash/css/CssBase.scala b/css/src/main/scala/io/udash/css/CssBase.scala
index 53126fc8b..a7582ff68 100644
--- a/css/src/main/scala/io/udash/css/CssBase.scala
+++ b/css/src/main/scala/io/udash/css/CssBase.scala
@@ -188,12 +188,12 @@ trait CssBase {
 }
 
 object CssBase {
-  class AnimationNameExt(private val n: Attrs.animationName.type) extends AnyVal {
+  final class AnimationNameExt(private val n: Attrs.animationName.type) extends AnyVal {
     def apply(s: CssStyle): AV =
       AV(n.attr, s.classNames.mkString(" "))
   }
 
-  class FontFamilyExt(private val n: Attrs.fontFamily.type) extends AnyVal {
+  final class FontFamilyExt(private val n: Attrs.fontFamily.type) extends AnyVal {
     def apply(s: CssStyle): AV =
       AV(n.attr, s.classNames.mkString(" "))
   }
diff --git a/css/src/main/scala/io/udash/css/CssStyle.scala b/css/src/main/scala/io/udash/css/CssStyle.scala
index 1d022fa85..0234b6881 100644
--- a/css/src/main/scala/io/udash/css/CssStyle.scala
+++ b/css/src/main/scala/io/udash/css/CssStyle.scala
@@ -9,15 +9,19 @@ sealed trait CssStyle {
   def commonPrefixClass: Option[String] = None
   def classNames: Seq[String] = commonPrefixClass.toList :+ className
 }
-case class CssStyleName(className: String) extends CssStyle
-case class CssPrefixedStyleName(prefixClass: String, actualClassSuffix: String) extends CssStyle {
+
+final case class CssStyleName(className: String) extends CssStyle
+
+final case class CssPrefixedStyleName(prefixClass: String, actualClassSuffix: String) extends CssStyle {
   val className = s"$prefixClass-$actualClassSuffix"
   override val commonPrefixClass: Option[String] = Some(prefixClass)
 }
-case class CssStyleNameWithSharedCompanion(companionClass: String, commonPrefix: String, className: String) extends CssStyle {
+
+final case class CssStyleNameWithSharedCompanion(companionClass: String, commonPrefix: String, className: String) extends CssStyle {
   override val commonPrefixClass: Option[String] = Some(commonPrefix)
   override def classNames: Seq[String] = Seq(companionClass, className)
 }
-case class CssStyleImpl(className: String, impl: StyleS) extends CssStyle
-case class CssKeyframes(className: String, steps: Seq[(Double, StyleS)]) extends CssStyle
-case class CssFontFace(className: String, font: FontFace[Option[String]]) extends CssStyle
+
+final case class CssStyleImpl(className: String, impl: StyleS) extends CssStyle
+final case class CssKeyframes(className: String, steps: Seq[(Double, StyleS)]) extends CssStyle
+final case class CssFontFace(className: String, font: FontFace[Option[String]]) extends CssStyle
diff --git a/guide/commons/.js/src/main/scala/io/udash/web/commons/views/ImageFactory.scala b/guide/commons/.js/src/main/scala/io/udash/web/commons/views/ImageFactory.scala
index adbdd3b28..180abb8f3 100644
--- a/guide/commons/.js/src/main/scala/io/udash/web/commons/views/ImageFactory.scala
+++ b/guide/commons/.js/src/main/scala/io/udash/web/commons/views/ImageFactory.scala
@@ -40,4 +40,4 @@ object SVG {
   }
 }
 
-case class Size(width: Int, height: Int)
\ No newline at end of file
+final case class Size(width: Int, height: Int)
diff --git a/guide/guide/.js/src/main/scala/io/udash/web/guide/RoutingStatesDef.scala b/guide/guide/.js/src/main/scala/io/udash/web/guide/RoutingStatesDef.scala
index b7123b248..1fc76593c 100644
--- a/guide/guide/.js/src/main/scala/io/udash/web/guide/RoutingStatesDef.scala
+++ b/guide/guide/.js/src/main/scala/io/udash/web/guide/RoutingStatesDef.scala
@@ -49,7 +49,7 @@ case object FrontendState extends ContainerRoutingState(Some(ContentState))
 
 case object FrontendIntroState extends RoutingState(Some(FrontendState))
 
-case class FrontendRoutingState(additionalArgument: Option[String]) extends RoutingState(Some(FrontendState))
+final case class FrontendRoutingState(additionalArgument: Option[String]) extends RoutingState(Some(FrontendState))
 
 case object FrontendMVPState extends RoutingState(Some(FrontendState))
 
diff --git a/guide/guide/.js/src/main/scala/io/udash/web/guide/components/GuideMenu.scala b/guide/guide/.js/src/main/scala/io/udash/web/guide/components/GuideMenu.scala
index f51b2ef35..3999f8f5f 100644
--- a/guide/guide/.js/src/main/scala/io/udash/web/guide/components/GuideMenu.scala
+++ b/guide/guide/.js/src/main/scala/io/udash/web/guide/components/GuideMenu.scala
@@ -18,8 +18,8 @@ sealed trait MenuEntry {
   def name: String
 }
 
-case class MenuContainer(override val name: String, children: Seq[MenuLink]) extends MenuEntry
-case class MenuLink(override val name: String, state: RoutingState, fragment: OptArg[String] = OptArg.Empty) extends MenuEntry
+final case class MenuContainer(override val name: String, children: Seq[MenuLink]) extends MenuEntry
+final case class MenuLink(override val name: String, state: RoutingState, fragment: OptArg[String] = OptArg.Empty) extends MenuEntry
 
 class GuideMenu(entries: Seq[MenuEntry], property: Property[String]) {
 
diff --git a/guide/guide/.js/src/main/scala/io/udash/web/guide/views/frontend/demos/IntroFormDemo.scala b/guide/guide/.js/src/main/scala/io/udash/web/guide/views/frontend/demos/IntroFormDemo.scala
index 5067fc6fe..7a1c14a22 100644
--- a/guide/guide/.js/src/main/scala/io/udash/web/guide/views/frontend/demos/IntroFormDemo.scala
+++ b/guide/guide/.js/src/main/scala/io/udash/web/guide/views/frontend/demos/IntroFormDemo.scala
@@ -7,7 +7,7 @@ import scalatags.JsDom.all._
 
 object IntroFormDemo extends AutoDemo {
 
-  case class IntroFormDemoModel(minimum: Int, between: Int, maximum: Int)
+  final case class IntroFormDemoModel(minimum: Int, between: Int, maximum: Int)
 
   object IntroFormDemoModel extends HasModelPropertyCreator[IntroFormDemoModel]
 
diff --git a/guide/guide/.js/src/main/scala/io/udash/web/guide/views/rpc/demos/ExceptionsDemoComponent.scala b/guide/guide/.js/src/main/scala/io/udash/web/guide/views/rpc/demos/ExceptionsDemoComponent.scala
index 3db2ae1ae..6a91d2d71 100644
--- a/guide/guide/.js/src/main/scala/io/udash/web/guide/views/rpc/demos/ExceptionsDemoComponent.scala
+++ b/guide/guide/.js/src/main/scala/io/udash/web/guide/views/rpc/demos/ExceptionsDemoComponent.scala
@@ -16,10 +16,10 @@ import scala.concurrent.duration.DurationLong
 import scala.language.postfixOps
 import scala.util.{Failure, Success}
 
-case class ExceptionsDemoModel(
+final case class ExceptionsDemoModel(
   exception: String,
   translatableException: TranslationKey0,
-  unknownException: String
+  unknownException: String,
 )
 object ExceptionsDemoModel extends HasModelPropertyCreator[ExceptionsDemoModel]
 
diff --git a/guide/shared/src/main/scala/io/udash/web/guide/GuideExceptions.scala b/guide/shared/src/main/scala/io/udash/web/guide/GuideExceptions.scala
index ab67c6990..f9442fce6 100644
--- a/guide/shared/src/main/scala/io/udash/web/guide/GuideExceptions.scala
+++ b/guide/shared/src/main/scala/io/udash/web/guide/GuideExceptions.scala
@@ -6,8 +6,8 @@ import io.udash.i18n.TranslationKey0
 import io.udash.rpc.serialization.{DefaultExceptionCodecRegistry, ExceptionCodecRegistry}
 
 object GuideExceptions {
-  case class ExampleException(msg: String) extends Exception(msg)
-  case class TranslatableExampleException(trKey: TranslationKey0) extends Exception
+  final case class ExampleException(msg: String) extends Exception(msg)
+  final case class TranslatableExampleException(trKey: TranslationKey0) extends Exception
 
   val registry: ExceptionCodecRegistry = (new DefaultExceptionCodecRegistry).setup { registry =>
     registry.register(GenCodec.materialize[ExampleException])
diff --git a/guide/shared/src/main/scala/io/udash/web/guide/demos/activity/Call.scala b/guide/shared/src/main/scala/io/udash/web/guide/demos/activity/Call.scala
index 6ec5ed263..315b3533e 100644
--- a/guide/shared/src/main/scala/io/udash/web/guide/demos/activity/Call.scala
+++ b/guide/shared/src/main/scala/io/udash/web/guide/demos/activity/Call.scala
@@ -2,7 +2,7 @@ package io.udash.web.guide.demos.activity
 
 import com.avsystem.commons.serialization.HasGenCodec
 
-case class Call(rpcName: String, method: String, args: Seq[String]) {
+final case class Call(rpcName: String, method: String, args: Seq[String]) {
   override def toString: String = s"$rpcName.$method args: ${args.mkString("[", ", ", "]")}"
 }
 object Call extends HasGenCodec[Call]
\ No newline at end of file
diff --git a/guide/shared/src/main/scala/io/udash/web/guide/demos/rest/RestExampleClass.scala b/guide/shared/src/main/scala/io/udash/web/guide/demos/rest/RestExampleClass.scala
index 81848c625..57b91817a 100644
--- a/guide/shared/src/main/scala/io/udash/web/guide/demos/rest/RestExampleClass.scala
+++ b/guide/shared/src/main/scala/io/udash/web/guide/demos/rest/RestExampleClass.scala
@@ -2,8 +2,8 @@ package io.udash.web.guide.demos.rest
 
 import io.udash.rest.RestDataCompanion
 
-case class RestExampleClass(i: Int, s: String, inner: InnerClass)
+final case class RestExampleClass(i: Int, s: String, inner: InnerClass)
 object RestExampleClass extends RestDataCompanion[RestExampleClass]
 
-case class InnerClass(d: Double, s: String)
+final case class InnerClass(d: Double, s: String)
 object InnerClass extends RestDataCompanion[InnerClass]
\ No newline at end of file
diff --git a/guide/shared/src/main/scala/io/udash/web/guide/demos/rpc/GenCodecServerRPC.scala b/guide/shared/src/main/scala/io/udash/web/guide/demos/rpc/GenCodecServerRPC.scala
index c627d5c5c..0bd6878cf 100644
--- a/guide/shared/src/main/scala/io/udash/web/guide/demos/rpc/GenCodecServerRPC.scala
+++ b/guide/shared/src/main/scala/io/udash/web/guide/demos/rpc/GenCodecServerRPC.scala
@@ -6,7 +6,7 @@ import io.udash.rpc._
 import scala.concurrent.Future
 
 object GenCodecServerRPC extends DefaultServerRpcCompanion[GenCodecServerRPC] {
-  case class DemoCaseClass(i: Int, s: String, intAsDouble: Double)
+  final case class DemoCaseClass(i: Int, s: String, intAsDouble: Double)
   object DemoCaseClass extends HasGenCodec[DemoCaseClass]
 
   sealed trait Fruit
diff --git a/project/Dependencies.scala b/project/Dependencies.scala
index 253516d6f..fdc0271df 100644
--- a/project/Dependencies.scala
+++ b/project/Dependencies.scala
@@ -14,7 +14,7 @@ object Dependencies {
   val scalaCssVersion = "1.0.0"
 
   val servletVersion = "4.0.1"
-  val avsCommonsVersion = "2.22.0"
+  val avsCommonsVersion = "2.23.0"
 
   val atmosphereJSVersion = "3.1.3"
   val atmosphereVersion = "2.7.15"
diff --git a/rest/.jvm/src/test/scala/io/udash/rest/examples/UserApi.scala b/rest/.jvm/src/test/scala/io/udash/rest/examples/UserApi.scala
index d3c47601d..89181b980 100644
--- a/rest/.jvm/src/test/scala/io/udash/rest/examples/UserApi.scala
+++ b/rest/.jvm/src/test/scala/io/udash/rest/examples/UserApi.scala
@@ -12,12 +12,12 @@ trait UserApi {
 }
 object UserApi extends DefaultRestApiCompanion[UserApi]
 
-case class UserId(id: Long) extends AnyVal
+final case class UserId(id: Long) extends AnyVal
 object UserId extends RestDataWrapperCompanion[Long, UserId]
 
 @description("Representation of system user")
 @example(User(UserId(0), "Fred"))
-case class User(id: UserId, @description("User name") name: String)
+final case class User(id: UserId, @description("User name") name: String)
 object User extends RestDataCompanion[User]
 
 trait GroupApi
diff --git a/rest/src/main/scala/io/udash/rest/openapi/OpenApi.scala b/rest/src/main/scala/io/udash/rest/openapi/OpenApi.scala
index e839e5e42..87c054048 100644
--- a/rest/src/main/scala/io/udash/rest/openapi/OpenApi.scala
+++ b/rest/src/main/scala/io/udash/rest/openapi/OpenApi.scala
@@ -308,7 +308,7 @@ object Schema extends HasGenObjectCodec[Schema] {
       Schema(allOf = List(ref), nullable = true)
   }
 
-  implicit class RefOrOps(private val refOrSchema: RefOr[Schema]) extends AnyVal {
+  implicit final class RefOrOps(private val refOrSchema: RefOr[Schema]) extends AnyVal {
     /**
       * Transforms a potential schema reference into an actual [[Schema]] by wrapping the reference into
       * `allOf` property of the new schema, e.g. `{"$$ref": "#/components/schemas/Entity"}` becomes
diff --git a/rest/src/main/scala/io/udash/rest/raw/RestRequest.scala b/rest/src/main/scala/io/udash/rest/raw/RestRequest.scala
index eafaaf09e..e2994af40 100644
--- a/rest/src/main/scala/io/udash/rest/raw/RestRequest.scala
+++ b/rest/src/main/scala/io/udash/rest/raw/RestRequest.scala
@@ -23,14 +23,14 @@ final case class RestParameters(
   @multi @tagged[Path] path: List[PlainValue] = Nil,
   @multi @tagged[Header] @allowOptional headers: IMapping[PlainValue] = IMapping.empty,
   @multi @tagged[Query] @allowOptional query: Mapping[PlainValue] = Mapping.empty,
-  @multi @tagged[Cookie] @allowOptional cookies: Mapping[PlainValue] = Mapping.empty
+  @multi @tagged[Cookie] @allowOptional cookies: Mapping[PlainValue] = Mapping.empty,
 ) {
   def append(method: RestMethodMetadata[_], otherParameters: RestParameters): RestParameters =
     RestParameters(
       path ::: method.applyPathParams(otherParameters.path),
       headers ++ otherParameters.headers,
       query ++ otherParameters.query,
-      cookies ++ otherParameters.cookies
+      cookies ++ otherParameters.cookies,
     )
 
   def path(values: String*): RestParameters =
@@ -49,7 +49,7 @@ object RestParameters {
   final val Empty = RestParameters()
 }
 
-case class HttpErrorException(code: Int, payload: HttpBody = HttpBody.Empty, cause: Throwable = null)
+final case class HttpErrorException(code: Int, payload: HttpBody = HttpBody.Empty, cause: Throwable = null)
   extends RuntimeException(s"HTTP ERROR $code${payload.textualContentOpt.fold("")(p => s": $p")}", cause) with NoStackTrace {
   def toResponse: RestResponse = RestResponse(code, IMapping.empty, payload)
 }
diff --git a/rest/src/main/scala/io/udash/rest/raw/RestResponse.scala b/rest/src/main/scala/io/udash/rest/raw/RestResponse.scala
index 836d0dbbb..3d34d696f 100644
--- a/rest/src/main/scala/io/udash/rest/raw/RestResponse.scala
+++ b/rest/src/main/scala/io/udash/rest/raw/RestResponse.scala
@@ -40,14 +40,14 @@ object RestResponse extends RestResponseLowPrio {
   def plain(status: Int, message: OptArg[String] = OptArg.Empty): RestResponse =
     RestResponse(status, IMapping.empty, HttpBody.plain(message))
 
-  class LazyOps(private val resp: () => RestResponse) extends AnyVal {
+  final class LazyOps(private val resp: () => RestResponse) extends AnyVal {
     def recoverHttpError: RestResponse = try resp() catch {
       case e: HttpErrorException => e.toResponse
     }
   }
   implicit def lazyOps(resp: => RestResponse): LazyOps = new LazyOps(() => resp)
 
-  implicit class TaskOps(private val asyncResp: Task[RestResponse]) extends AnyVal {
+  implicit final class TaskOps(private val asyncResp: Task[RestResponse]) extends AnyVal {
     def recoverHttpError: Task[RestResponse] =
       asyncResp.onErrorRecover {
         case e: HttpErrorException => e.toResponse
@@ -171,14 +171,14 @@ object StreamedRestResponse extends StreamedRestResponseLowPrio {
   def fromHttpError(error: HttpErrorException): StreamedRestResponse =
     StreamedRestResponse(error.code, IMapping.empty, StreamedBody.fromHttpBody(error.payload))
 
-  class LazyOps(private val resp: () => StreamedRestResponse) extends AnyVal {
+  final class LazyOps(private val resp: () => StreamedRestResponse) extends AnyVal {
     def recoverHttpError: StreamedRestResponse = try resp() catch {
       case e: HttpErrorException => StreamedRestResponse.fromHttpError(e)
     }
   }
   implicit def lazyOps(resp: => StreamedRestResponse): LazyOps = new LazyOps(() => resp)
 
-  implicit class TaskOps(private val asyncResp: Task[StreamedRestResponse]) extends AnyVal {
+  implicit final class TaskOps(private val asyncResp: Task[StreamedRestResponse]) extends AnyVal {
     def recoverHttpError: Task[StreamedRestResponse] =
       asyncResp.onErrorRecover {
         case e: HttpErrorException => StreamedRestResponse.fromHttpError(e)
diff --git a/rest/src/main/scala/io/udash/rest/util/WithHeaders.scala b/rest/src/main/scala/io/udash/rest/util/WithHeaders.scala
index c8d8edb82..b309c2def 100644
--- a/rest/src/main/scala/io/udash/rest/util/WithHeaders.scala
+++ b/rest/src/main/scala/io/udash/rest/util/WithHeaders.scala
@@ -13,7 +13,7 @@ import io.udash.rest.raw.{HttpBody, IMapping, PlainValue, RestResponse}
  * If you want to include this information into OpenAPI definition for method that returns `WithHeaders`,
  * you may use [[io.udash.rest.adjustResponse adjustResponse]] on it.
  */
-case class WithHeaders[+T](value: T, headers: ISeq[(String, String)])
+final case class WithHeaders[+T](value: T, headers: ISeq[(String, String)])
 object WithHeaders {
   implicit def asResponse[T](implicit wrapped: AsRaw[HttpBody, T]): AsRaw[RestResponse, WithHeaders[T]] = {
     case WithHeaders(value, headers) =>
diff --git a/rest/src/test/scala/io/udash/rest/CirceRestApiTest.scala b/rest/src/test/scala/io/udash/rest/CirceRestApiTest.scala
index 31406349c..44ef2ee30 100644
--- a/rest/src/test/scala/io/udash/rest/CirceRestApiTest.scala
+++ b/rest/src/test/scala/io/udash/rest/CirceRestApiTest.scala
@@ -79,10 +79,10 @@ abstract class HasCirceCustomizedCodec[T](
   implicit final lazy val decoder: Decoder[T] = instances((), this).decoder(nameTransform, useDefaults, discriminator)
 }
 
-case class CirceAddress(city: String, zip: String)
+final case class CirceAddress(city: String, zip: String)
 object CirceAddress extends HasCirceCustomizedCodec[CirceAddress](_.toUpperCase)
 
-case class CircePerson(id: Long, name: String, address: Option[CirceAddress] = None)
+final case class CircePerson(id: Long, name: String, address: Option[CirceAddress] = None)
 object CircePerson extends HasCirceCodec[CircePerson]
 
 abstract class CirceRestApiCompanion[T](
diff --git a/rest/src/test/scala/io/udash/rest/RestTestApi.scala b/rest/src/test/scala/io/udash/rest/RestTestApi.scala
index 64ad06b33..2f217fd28 100644
--- a/rest/src/test/scala/io/udash/rest/RestTestApi.scala
+++ b/rest/src/test/scala/io/udash/rest/RestTestApi.scala
@@ -16,7 +16,7 @@ import scala.concurrent.Future
 import scala.concurrent.duration.*
 
 @description("Entity identifier")
-case class RestEntityId(value: String) extends AnyVal
+final case class RestEntityId(value: String) extends AnyVal
 object RestEntityId extends RestDataWrapperCompanion[String, RestEntityId]
 
 @name("RestEntityEnumCustom")
@@ -42,7 +42,7 @@ object BaseEntity extends RestDataCompanion[BaseEntity]
 object FlatBaseEntity extends RestDataCompanion[FlatBaseEntity]
 
 @description("REST entity")
-case class RestEntity(
+final case class RestEntity(
   @description("entity id") id: RestEntityId,
   @whenAbsent("anonymous") name: String = whenAbsent.value,
   @description("recursive optional subentity") subentity: OptArg[RestEntity] = OptArg.Empty,
@@ -52,11 +52,11 @@ case class RestEntity(
 ) extends FlatBaseEntity
 object RestEntity extends RestDataCompanion[RestEntity]
 
-case class RestOtherEntity(fuu: Boolean, kek: List[String]) extends FlatBaseEntity
+final case class RestOtherEntity(fuu: Boolean, kek: List[String]) extends FlatBaseEntity
 
 case object SingletonEntity extends FlatBaseEntity
 
-case class CustomResp(value: String)
+final case class CustomResp(value: String)
 object CustomResp {
   implicit val asResponse: AsRawReal[RestResponse, CustomResp] = AsRawReal.create(
     cr => RestResponse(200, IMapping.create("X-Value" -> PlainValue(cr.value)), HttpBody.plain("Yes")),
@@ -77,10 +77,10 @@ object CustomResp {
 }
 
 @description("binary bytes")
-case class Bytes(bytes: Array[Byte]) extends AnyVal
+final case class Bytes(bytes: Array[Byte]) extends AnyVal
 object Bytes extends RestDataWrapperCompanion[Array[Byte], Bytes]
 
-case class ThirdParty(thing: Int)
+final case class ThirdParty(thing: Int)
 object ThirdPartyImplicits {
   implicit val thirdPartyCodec: GenCodec[ThirdParty] =
     GenCodec.materialize[ThirdParty]
@@ -88,10 +88,10 @@ object ThirdPartyImplicits {
     RestStructure.materialize[ThirdParty].standaloneSchema
 }
 
-case class HasThirdParty(dur: ThirdParty)
+final case class HasThirdParty(dur: ThirdParty)
 object HasThirdParty extends RestDataCompanionWithDeps[ThirdPartyImplicits.type, HasThirdParty]
 
-case class ErrorWrapper[T](error: T)
+final case class ErrorWrapper[T](error: T)
 object ErrorWrapper extends HasPolyGenCodec[ErrorWrapper]
 
 trait RestTestApi {
diff --git a/rest/src/test/scala/io/udash/rest/TestRESTRecord.scala b/rest/src/test/scala/io/udash/rest/TestRESTRecord.scala
index 02f0a6591..994dbc465 100644
--- a/rest/src/test/scala/io/udash/rest/TestRESTRecord.scala
+++ b/rest/src/test/scala/io/udash/rest/TestRESTRecord.scala
@@ -1,5 +1,5 @@
 package io.udash
 package rest
 
-case class TestRESTRecord(id: Option[Int], s: String)
+final case class TestRESTRecord(id: Option[Int], s: String)
 object TestRESTRecord extends RestDataCompanion[TestRESTRecord]
\ No newline at end of file
diff --git a/rest/src/test/scala/io/udash/rest/openapi/RestSchemaTest.scala b/rest/src/test/scala/io/udash/rest/openapi/RestSchemaTest.scala
index 18e051c05..183591cfd 100644
--- a/rest/src/test/scala/io/udash/rest/openapi/RestSchemaTest.scala
+++ b/rest/src/test/scala/io/udash/rest/openapi/RestSchemaTest.scala
@@ -23,7 +23,7 @@ object Dependency {
 }
 
 @description("kejs klass")
-case class KejsKlass(
+final case class KejsKlass(
   @name("integer") @customWa(42) int: Int,
   @description("serious dependency") dep: Dependency,
   @description("optional thing") @optionalParam opty: Opt[String] = Opt("defaultThatMustBeIgnored"),
@@ -32,13 +32,13 @@ case class KejsKlass(
 object KejsKlass extends RestDataCompanion[KejsKlass]
 
 @description("wrapped string")
-@transparent case class Wrap(str: String)
+@transparent final case class Wrap(str: String)
 object Wrap extends RestDataCompanion[Wrap]
 
-case class PlainGenericCC[+T](thing: T)
+final case class PlainGenericCC[+T](thing: T)
 object PlainGenericCC extends PolyRestDataCompanion[PlainGenericCC]
 
-case class GenCC[+T >: Null](@customWa[T](null) value: T)
+final case class GenCC[+T >: Null](@customWa[T](null) value: T)
 object GenCC extends RestDataCompanion[GenCC[String]]
 
 final class KeyEnum(implicit enumCtx: EnumCtx) extends AbstractValueEnum
@@ -48,7 +48,7 @@ object KeyEnum extends AbstractValueEnumCompanion[KeyEnum] {
 
 @flatten("tpe")
 sealed trait HierarchyRoot[+T]
-case class HierarchyCase[+T](value: T) extends HierarchyRoot[T]
+final case class HierarchyCase[+T](value: T) extends HierarchyRoot[T]
 object HierarchyCase {
   implicit val stringRestSchema: RestSchema[HierarchyCase[String]] =
     RestStructure.materialize[HierarchyCase[String]] match {
@@ -65,8 +65,8 @@ object HierarchyRoot {
 
 @flatten("case") sealed trait FullyQualifiedHierarchy
 object FullyQualifiedHierarchy extends RestDataCompanionWithDeps[FullyQualifiedNames.type, FullyQualifiedHierarchy] {
-  case class Foo(str: String) extends FullyQualifiedHierarchy
-  case class Bar(int: Int) extends FullyQualifiedHierarchy
+  final case class Foo(str: String) extends FullyQualifiedHierarchy
+  final case class Bar(int: Int) extends FullyQualifiedHierarchy
   object Bar extends RestDataCompanionWithDeps[FullyQualifiedNames.type, Bar]
   case object Baz extends FullyQualifiedHierarchy
 }
@@ -76,15 +76,15 @@ sealed trait CustomSchemaNameHierarchy
 object CustomSchemaNameHierarchy extends RestDataCompanion[CustomSchemaNameHierarchy] {
   // annotation value should be used as schema name, but NOT as type discriminator value
   @schemaName("CustomSchemaName123")
-  case class CustomSchemaName(str: String) extends CustomSchemaNameHierarchy
+  final case class CustomSchemaName(str: String) extends CustomSchemaNameHierarchy
 
   // annotation value should be used as both schema name and type discriminator value
   @name("CustomName123")
-  case class CustomName(str: String) extends CustomSchemaNameHierarchy
+  final case class CustomName(str: String) extends CustomSchemaNameHierarchy
 
   // @schemaName annotation should be used as schema name, @name annotation should be used only as type discriminator value
   @schemaName("CustomSchemaNameBoth") @name("CustomNameBoth123")
-  case class CustomNameBoth(str: String) extends CustomSchemaNameHierarchy
+  final case class CustomNameBoth(str: String) extends CustomSchemaNameHierarchy
 }
 
 class RestSchemaTest extends AnyFunSuite {
diff --git a/rest/src/test/scala/io/udash/rest/openapi/openapiDependencies.scala b/rest/src/test/scala/io/udash/rest/openapi/openapiDependencies.scala
index c307f261a..a815d6341 100644
--- a/rest/src/test/scala/io/udash/rest/openapi/openapiDependencies.scala
+++ b/rest/src/test/scala/io/udash/rest/openapi/openapiDependencies.scala
@@ -49,7 +49,7 @@ class descriptionKey(key: String, @infer i18n: I18N = infer.value)
   extends description(i18n.t(key))
 
 @descriptionKey("person.desc")
-case class Person(
+final case class Person(
   @descriptionKey("name.desc") name: String
 )
 object Person extends I18NRestDataCompanion[Person]
diff --git a/rest/src/test/scala/io/udash/rest/raw/RawRestTest.scala b/rest/src/test/scala/io/udash/rest/raw/RawRestTest.scala
index 16e71ee79..ec0c976f2 100644
--- a/rest/src/test/scala/io/udash/rest/raw/RawRestTest.scala
+++ b/rest/src/test/scala/io/udash/rest/raw/RawRestTest.scala
@@ -15,15 +15,15 @@ import org.scalatest.concurrent.ScalaFutures
 import org.scalatest.funsuite.AnyFunSuite
 import org.scalatest.matchers.should.Matchers
 
-case class UserId(id: String) extends AnyVal {
+final case class UserId(id: String) extends AnyVal {
   override def toString: String = id
 }
 object UserId extends RestDataWrapperCompanion[String, UserId]
 
-case class User(id: UserId, name: String)
+final case class User(id: UserId, name: String)
 object User extends RestDataCompanion[User]
 
-case class NonBlankString(str: String) {
+final case class NonBlankString(str: String) {
   if (str.isBlank) {
     throw HttpErrorException(400, HttpBody.plain("this stuff is blank"))
   }
diff --git a/rpc/.js/src/main/scala/io/udash/rpc/internals/UsesServerRPC.scala b/rpc/.js/src/main/scala/io/udash/rpc/internals/UsesServerRPC.scala
index 9a5c86417..0b70f99e9 100644
--- a/rpc/.js/src/main/scala/io/udash/rpc/internals/UsesServerRPC.scala
+++ b/rpc/.js/src/main/scala/io/udash/rpc/internals/UsesServerRPC.scala
@@ -1,7 +1,7 @@
 package io.udash.rpc.internals
 
-import com.avsystem.commons.SharedExtensions._
-import io.udash.rpc._
+import com.avsystem.commons.SharedExtensions.*
+import io.udash.rpc.*
 import io.udash.utils.{CallbacksHandler, Registration}
 import org.scalajs.dom
 
@@ -96,5 +96,5 @@ private[rpc] trait UsesServerRPC[ServerRPCType] extends UsesRemoteRPC[ServerRPCT
 }
 
 object UsesServerRPC {
-  case class CallTimeout(callTimeout: Duration) extends RuntimeException(s"Response missing after $callTimeout.")
+  final case class CallTimeout(callTimeout: Duration) extends RuntimeException(s"Response missing after $callTimeout.")
 }
diff --git a/rpc/.jvm/src/main/scala/io/udash/rpc/DefaultClientRPC.scala b/rpc/.jvm/src/main/scala/io/udash/rpc/DefaultClientRPC.scala
index a35141405..086bb675b 100644
--- a/rpc/.jvm/src/main/scala/io/udash/rpc/DefaultClientRPC.scala
+++ b/rpc/.jvm/src/main/scala/io/udash/rpc/DefaultClientRPC.scala
@@ -13,7 +13,7 @@ import scala.concurrent.ExecutionContext
   */
 sealed trait ClientRPCTarget
 case object AllClients extends ClientRPCTarget
-case class ClientId(id: String) extends ClientRPCTarget
+final case class ClientId(id: String) extends ClientRPCTarget
 
 abstract class ClientRPC[ClientRPCType](target: ClientRPCTarget)
   (implicit ec: ExecutionContext) extends UsesClientRPC[ClientRPCType] {
diff --git a/rpc/.jvm/src/test/scala/io/udash/rpc/DefaultExceptionCodecRegistryTest.scala b/rpc/.jvm/src/test/scala/io/udash/rpc/DefaultExceptionCodecRegistryTest.scala
index f7611d372..63ef3f9fb 100644
--- a/rpc/.jvm/src/test/scala/io/udash/rpc/DefaultExceptionCodecRegistryTest.scala
+++ b/rpc/.jvm/src/test/scala/io/udash/rpc/DefaultExceptionCodecRegistryTest.scala
@@ -6,11 +6,11 @@ import io.udash.testing.UdashSharedTest
 
 private sealed trait RootTrait extends Throwable
 private sealed trait SubTrait extends RootTrait
-private case class SubTraitImpl() extends SubTrait
+private final case class SubTraitImpl() extends SubTrait
 
 private sealed trait SealedHierarchy extends Throwable
-private case class SealedHierarchyA(a: Int) extends SealedHierarchy
-private case class SealedHierarchyB(b: Double) extends SealedHierarchy
+private final case class SealedHierarchyA(a: Int) extends SealedHierarchy
+private final case class SealedHierarchyB(b: Double) extends SealedHierarchy
 
 class DefaultExceptionCodecRegistryTest extends UdashSharedTest with Utils  {
   val exceptionsRegistry: ExceptionCodecRegistry = new DefaultExceptionCodecRegistry
diff --git a/rpc/src/main/scala/io/udash/rpc/rawrpc.scala b/rpc/src/main/scala/io/udash/rpc/rawrpc.scala
index 61c18ca52..bc8a739f2 100644
--- a/rpc/src/main/scala/io/udash/rpc/rawrpc.scala
+++ b/rpc/src/main/scala/io/udash/rpc/rawrpc.scala
@@ -12,11 +12,11 @@ import io.udash.rpc.utils.Logged
 import scala.annotation.implicitNotFound
 import scala.concurrent.Future
 
-case class JsonStr(json: String) extends AnyVal
+final case class JsonStr(json: String) extends AnyVal
 object JsonStr {
   implicit val codec: GenCodec[JsonStr] = GenCodec.create(
     i => JsonStr(i.readCustom(RawJson).getOrElse(i.readSimple().readString())),
-    (o, v) => if (!o.writeCustom(RawJson, v.json)) o.writeSimple().writeString(v.json)
+    (o, v) => if (!o.writeCustom(RawJson, v.json)) o.writeSimple().writeString(v.json),
   )
 
   implicit def futureAsReal[T](implicit asReal: AsReal[JsonStr, T]): AsReal[Future[JsonStr], Future[T]] =
@@ -36,10 +36,10 @@ object JsonStr {
   ): ImplicitNotFound[AsRaw[Future[JsonStr], Future[T]]] = ImplicitNotFound()
 }
 
-case class RpcInvocation(@methodName rpcName: String, @multi args: List[JsonStr])
+final case class RpcInvocation(@methodName rpcName: String, @multi args: List[JsonStr])
 object RpcInvocation extends HasGenCodec[RpcInvocation]
 
-case class RpcFailure(remoteCause: String, remoteMessage: String)
+final case class RpcFailure(remoteCause: String, remoteMessage: String)
   extends Exception(s"$remoteCause: $remoteMessage")
 object RpcFailure extends HasGenCodec[RpcFailure]
 
@@ -56,12 +56,12 @@ sealed trait RpcRequest {
 object RpcRequest extends HasGenCodec[RpcRequest]
 
 /** [[RpcRequest]] which returns some value. */
-case class RpcCall(invocation: RpcInvocation, gettersChain: List[RpcInvocation], callId: String)
+final case class RpcCall(invocation: RpcInvocation, gettersChain: List[RpcInvocation], callId: String)
   extends RpcRequest
 object RpcCall extends HasGenCodec[RpcCall]
 
 /** [[RpcRequest]] which returns Unit. */
-case class RpcFire(invocation: RpcInvocation, gettersChain: List[RpcInvocation])
+final case class RpcFire(invocation: RpcInvocation, gettersChain: List[RpcInvocation])
   extends RpcRequest with RpcServerMessage
 object RpcFire extends HasGenCodec[RpcFire]
 
@@ -74,11 +74,11 @@ object RpcResponse {
 }
 
 /** Message containing response for [[RpcCall]]. */
-case class RpcResponseSuccess(response: JsonStr, callId: String) extends RpcResponse
+final case class RpcResponseSuccess(response: JsonStr, callId: String) extends RpcResponse
 /** Message reporting failure of [[RpcCall]]. */
-case class RpcResponseFailure(cause: String, errorMsg: String, callId: String) extends RpcResponse
+final case class RpcResponseFailure(cause: String, errorMsg: String, callId: String) extends RpcResponse
 /** Message reporting exception from [[RpcCall]]. */
-case class RpcResponseException(name: String, exception: Throwable, callId: String) extends RpcResponse
+final case class RpcResponseException(name: String, exception: Throwable, callId: String) extends RpcResponse
 object RpcResponseException {
   implicit def codec(implicit ecr: ExceptionCodecRegistry): GenCodec[RpcResponseException] =
     GenCodec.nullableObject(
@@ -139,20 +139,20 @@ object ServerRawRpc extends RawRpcCompanion[ServerRawRpc] {
 }
 
 @allowIncomplete
-case class ServerRpcMetadata[T](
+final case class ServerRpcMetadata[T](
   @reifyName name: String,
   @multi @rpcMethodMetadata getters: Map[String, GetterMethod[_]],
-  @multi @rpcMethodMetadata methods: Map[String, RpcMethod[_]]
+  @multi @rpcMethodMetadata methods: Map[String, RpcMethod[_]],
 )
 object ServerRpcMetadata extends RpcMetadataCompanion[ServerRpcMetadata]
 
 @allowIncomplete
-case class GetterMethod[T](
+final case class GetterMethod[T](
   @infer @checked resultMetadata: ServerRpcMetadata.Lazy[T]
 ) extends TypedMetadata[T]
 
 @allowIncomplete
-case class RpcMethod[T](
+final case class RpcMethod[T](
   @reifyName name: String,
   @isAnnotated[Logged] logged: Boolean,
 ) extends TypedMetadata[T]
diff --git a/rpc/src/test/scala/io/udash/rpc/RpcMessagesTest.scala b/rpc/src/test/scala/io/udash/rpc/RpcMessagesTest.scala
index 616c006b5..5b317c5e1 100644
--- a/rpc/src/test/scala/io/udash/rpc/RpcMessagesTest.scala
+++ b/rpc/src/test/scala/io/udash/rpc/RpcMessagesTest.scala
@@ -7,11 +7,11 @@ import io.udash.testing.UdashSharedTest
 
 import scala.util.Random
 
-private case class CustomException(error: String, counter: Int) extends Throwable
+private final case class CustomException(error: String, counter: Int) extends Throwable
 
 private sealed trait SealedExceptions extends Throwable
-private case class SealedExceptionsA(a: Int) extends SealedExceptions
-private case class SealedExceptionsB(b: Double) extends SealedExceptions
+private final case class SealedExceptionsA(a: Int) extends SealedExceptions
+private final case class SealedExceptionsB(b: Double) extends SealedExceptions
 
 trait RpcMessagesTestScenarios extends UdashSharedTest with Utils {
   val exceptionsRegistry: ExceptionCodecRegistry = new DefaultExceptionCodecRegistry
diff --git a/rpc/src/test/scala/io/udash/rpc/TestRPC.scala b/rpc/src/test/scala/io/udash/rpc/TestRPC.scala
index 1c0c1e0f2..485977afb 100644
--- a/rpc/src/test/scala/io/udash/rpc/TestRPC.scala
+++ b/rpc/src/test/scala/io/udash/rpc/TestRPC.scala
@@ -7,10 +7,10 @@ import io.udash.rpc.utils.Logged
 import scala.annotation.nowarn
 import scala.concurrent.Future
 
-case class Record(i: Int, fuu: String)
+final case class Record(i: Int, fuu: String)
 object Record extends HasGenCodec[Record]
 
-case class CustomRPCException(i: Int) extends Throwable
+final case class CustomRPCException(i: Int) extends Throwable
 object CustomRPCException extends HasGenCodec[CustomRPCException]
 
 trait RPCMethods {
@@ -47,7 +47,7 @@ trait InnerClientRPC {
 }
 object InnerClientRPC extends DefaultClientRpcCompanion[InnerClientRPC]
 
-case class External(x: Int)
+final case class External(x: Int)
 
 object ExternalTypeCodec {
   implicit val codec: GenCodec[External] = GenCodec.transformed[External, Int](_.x, External.apply)
diff --git a/rpc/src/test/scala/io/udash/rpc/types.scala b/rpc/src/test/scala/io/udash/rpc/types.scala
index 7ab001970..ff74f5c64 100644
--- a/rpc/src/test/scala/io/udash/rpc/types.scala
+++ b/rpc/src/test/scala/io/udash/rpc/types.scala
@@ -2,16 +2,16 @@ package io.udash.rpc
 
 import com.avsystem.commons.serialization.HasGenCodec
 
-case class TestCC(i: Int, l: Long, intAsDouble: Double, b: Boolean, s: String, list: List[Char])
+final case class TestCC(i: Int, l: Long, intAsDouble: Double, b: Boolean, s: String, list: List[Char])
 object TestCC extends HasGenCodec[TestCC]
 
-case class NestedTestCC(i: Int, t: TestCC, t2: TestCC)
+final case class NestedTestCC(i: Int, t: TestCC, t2: TestCC)
 object NestedTestCC extends HasGenCodec[NestedTestCC]
 
-case class DeepNestedTestCC(n: NestedTestCC, l: DeepNestedTestCC)
+final case class DeepNestedTestCC(n: NestedTestCC, l: DeepNestedTestCC)
 object DeepNestedTestCC extends HasGenCodec[DeepNestedTestCC]
 
-case class CompleteItem(unit: Unit, string: String, specialString: String, char: Char, boolean: Boolean, byte: Byte, short: Short, int: Int,
+final case class CompleteItem(unit: Unit, string: String, specialString: String, char: Char, boolean: Boolean, byte: Byte, short: Short, int: Int,
                         long: Long, float: Float, double: Double, binary: Array[Byte], list: List[String],
                         set: Set[String], obj: TestCC, map: Map[String, Int])
 object CompleteItem extends HasGenCodec[CompleteItem]
diff --git a/utils/.js/src/test/scala/io/udash/testing/AsyncUdashSharedTest.scala b/utils/.js/src/test/scala/io/udash/testing/AsyncUdashSharedTest.scala
index 334f6a796..db0014be4 100644
--- a/utils/.js/src/test/scala/io/udash/testing/AsyncUdashSharedTest.scala
+++ b/utils/.js/src/test/scala/io/udash/testing/AsyncUdashSharedTest.scala
@@ -7,6 +7,7 @@ import org.scalatest.{Assertion, Succeeded}
 import scala.concurrent.{ExecutionContext, Future, Promise}
 import scala.scalajs.concurrent.JSExecutionContext
 import scala.scalajs.js.Date
+import scala.util.control.NonFatal
 import scala.util.{Failure, Success}
 
 trait AsyncUdashSharedTest extends AsyncUdashSharedTestBase {
@@ -23,7 +24,7 @@ trait AsyncUdashSharedTest extends AsyncUdashSharedTestBase {
             code
             p.complete(Success(Succeeded))
           } catch {
-            case ex: Throwable =>
+            case NonFatal(ex) =>
               lastEx = Some(ex)
               startTest()
           }