diff --git a/vertx-core/src/main/java/io/vertx/core/impl/ContextImpl.java b/vertx-core/src/main/java/io/vertx/core/impl/ContextImpl.java
index 91e76096ba6..8856a1466e1 100644
--- a/vertx-core/src/main/java/io/vertx/core/impl/ContextImpl.java
+++ b/vertx-core/src/main/java/io/vertx/core/impl/ContextImpl.java
@@ -38,7 +38,7 @@ public final class ContextImpl extends ContextBase implements ContextInternal {
 
   static final boolean DISABLE_TIMINGS = SysProps.DISABLE_CONTEXT_TIMINGS.getBoolean();
 
-  private final VertxInternal owner;
+  private final VertxImpl owner;
   private final JsonObject config;
   private final DeploymentContext deployment;
   private final CloseFuture closeFuture;
@@ -51,7 +51,7 @@ public final class ContextImpl extends ContextBase implements ContextInternal {
   final WorkerPool workerPool;
   final WorkerTaskQueue executeBlockingTasks;
 
-  public ContextImpl(VertxInternal vertx,
+  public ContextImpl(VertxImpl vertx,
                      Object[] locals,
                      EventLoopExecutor eventLoop,
                      ThreadingModel threadingModel,
@@ -113,7 +113,7 @@ public EventLoop nettyEventLoop() {
     return eventLoop.eventLoop;
   }
 
-  public VertxInternal owner() {
+  public VertxImpl owner() {
     return owner;
   }
 
diff --git a/vertx-core/src/main/java/io/vertx/core/impl/ContextLocalImpl.java b/vertx-core/src/main/java/io/vertx/core/impl/ContextLocalImpl.java
index 02671c9a58c..2eb30e3273d 100644
--- a/vertx-core/src/main/java/io/vertx/core/impl/ContextLocalImpl.java
+++ b/vertx-core/src/main/java/io/vertx/core/impl/ContextLocalImpl.java
@@ -12,18 +12,27 @@
 
 import io.vertx.core.spi.context.storage.ContextLocal;
 
+import java.util.function.Function;
+
 /**
  * @author <a href="mailto:julien@julienviet.com">Julien Viet</a>
  */
 public class ContextLocalImpl<T> implements ContextLocal<T> {
 
+  public static <T> ContextLocal<T> create(Class<T> type, Function<T, T> duplicator) {
+    synchronized (LocalSeq.class) {
+      int idx = LocalSeq.locals.size();
+      ContextLocal<T> local = new ContextLocalImpl<>(idx, duplicator);
+      LocalSeq.locals.add(local);
+      return local;
+    }
+  }
+
   final int index;
+  final Function<T, T> duplicator;
 
-  public ContextLocalImpl(int index) {
+  public ContextLocalImpl(int index, Function<T, T> duplicator) {
     this.index = index;
-  }
-
-  public ContextLocalImpl() {
-    this.index = LocalSeq.next();
+    this.duplicator = duplicator;
   }
 }
diff --git a/vertx-core/src/main/java/io/vertx/core/impl/DuplicatedContext.java b/vertx-core/src/main/java/io/vertx/core/impl/DuplicatedContext.java
index dc2a4097d17..9c4ac2d6d9f 100644
--- a/vertx-core/src/main/java/io/vertx/core/impl/DuplicatedContext.java
+++ b/vertx-core/src/main/java/io/vertx/core/impl/DuplicatedContext.java
@@ -142,7 +142,9 @@ public boolean isWorkerContext() {
 
   @Override
   public ContextInternal duplicate() {
-    return new DuplicatedContext(delegate, locals.length == 0 ? VertxImpl.EMPTY_CONTEXT_LOCALS : new Object[locals.length]);
+    DuplicatedContext duplicate = new DuplicatedContext(delegate, locals.length == 0 ? VertxImpl.EMPTY_CONTEXT_LOCALS : new Object[locals.length]);
+    delegate.owner().duplicate(this, duplicate);
+    return duplicate;
   }
 
   @Override
diff --git a/vertx-core/src/main/java/io/vertx/core/impl/LocalSeq.java b/vertx-core/src/main/java/io/vertx/core/impl/LocalSeq.java
index 2089a3fd37b..17eff10fa25 100644
--- a/vertx-core/src/main/java/io/vertx/core/impl/LocalSeq.java
+++ b/vertx-core/src/main/java/io/vertx/core/impl/LocalSeq.java
@@ -10,6 +10,11 @@
  */
 package io.vertx.core.impl;
 
+import io.vertx.core.internal.ContextInternal;
+import io.vertx.core.spi.context.storage.ContextLocal;
+
+import java.util.ArrayList;
+import java.util.List;
 import java.util.concurrent.atomic.AtomicInteger;
 
 /**
@@ -18,20 +23,22 @@
 public class LocalSeq {
 
   // 0 : reserved slot for local context map
-  private static final AtomicInteger seq = new AtomicInteger(1);
+  static final List<ContextLocal<?>> locals = new ArrayList<>();
+
+  static {
+    reset();
+  }
 
   /**
    * Hook for testing purposes
    */
-  public static void reset() {
-    seq.set((1));
-  }
-
-  static int get() {
-    return seq.get();
+  public synchronized static void reset() {
+    // 0 : reserved slot for local context map
+    locals.clear();
+    locals.add(ContextInternal.LOCAL_MAP);
   }
 
-  static int next() {
-    return seq.getAndIncrement();
+  synchronized static ContextLocal<?>[] get() {
+    return locals.toArray(new ContextLocal[0]);
   }
 }
diff --git a/vertx-core/src/main/java/io/vertx/core/impl/VertxImpl.java b/vertx-core/src/main/java/io/vertx/core/impl/VertxImpl.java
index 5535cdaa67c..b25c70f7865 100644
--- a/vertx-core/src/main/java/io/vertx/core/impl/VertxImpl.java
+++ b/vertx-core/src/main/java/io/vertx/core/impl/VertxImpl.java
@@ -45,6 +45,8 @@
 import io.vertx.core.net.impl.*;
 import io.vertx.core.impl.transports.NioTransport;
 import io.vertx.core.spi.context.executor.EventExecutorProvider;
+import io.vertx.core.spi.context.storage.AccessMode;
+import io.vertx.core.spi.context.storage.ContextLocal;
 import io.vertx.core.spi.file.FileResolver;
 import io.vertx.core.file.impl.FileSystemImpl;
 import io.vertx.core.file.impl.WindowsFileSystem;
@@ -143,7 +145,8 @@ private static ThreadFactory virtualThreadFactory() {
   private final FileResolver fileResolver;
   private final EventExecutorProvider eventExecutorProvider;
   private final Map<ServerID, NetServerInternal> sharedNetServers = new HashMap<>();
-  private final int contextLocals;
+  private final ContextLocal<?>[] contextLocals;
+  private final List<ContextLocal<?>> contextLocalsList;
   final WorkerPool workerPool;
   final WorkerPool internalWorkerPool;
   final WorkerPool virtualThreaWorkerPool;
@@ -202,6 +205,7 @@ private static ThreadFactory virtualThreadFactory() {
     ThreadFactory virtualThreadFactory = virtualThreadFactory();
 
     contextLocals = LocalSeq.get();
+    contextLocalsList = Collections.unmodifiableList(Arrays.asList(contextLocals));
     closeFuture = new CloseFuture(log);
     maxEventLoopExecTime = maxEventLoopExecuteTime;
     maxEventLoopExecTimeUnit = maxEventLoopExecuteTimeUnit;
@@ -563,10 +567,10 @@ public boolean cancelTimer(long id) {
   }
 
   private Object[] createContextLocals() {
-    if (contextLocals == 0) {
+    if (contextLocals.length == 0) {
       return EMPTY_CONTEXT_LOCALS;
     } else {
-      return new Object[contextLocals];
+      return new Object[contextLocals.length];
     }
   }
 
@@ -936,6 +940,11 @@ public AddressResolverGroup<InetSocketAddress> nettyAddressResolverGroup() {
     return hostnameResolver.nettyAddressResolverGroup();
   }
 
+  @Override
+  public List<ContextLocal<?>> contextLocals() {
+    return contextLocalsList;
+  }
+
   @Override
   public FileResolver fileResolver() {
     return fileResolver;
@@ -1317,6 +1326,17 @@ public <C> C createSharedResource(String resourceKey, String resourceName, Close
     return SharedResourceHolder.createSharedResource(this, resourceKey, resourceName, closeFuture, supplier);
   }
 
+  void duplicate(ContextBase src, ContextBase dst) {
+    for (int i = 0;i < contextLocals.length;i++) {
+      ContextLocalImpl<?> contextLocal = (ContextLocalImpl<?>) contextLocals[i];
+      Object local = AccessMode.CONCURRENT.get(src.locals, i);
+      if (local != null) {
+        local = ((Function)contextLocal.duplicator).apply(local);
+      }
+      AccessMode.CONCURRENT.put(dst.locals, i, local);
+    }
+  }
+
   /**
    * Reads the version from the {@code vertx-version.txt} file.
    *
diff --git a/vertx-core/src/main/java/io/vertx/core/internal/ContextInternal.java b/vertx-core/src/main/java/io/vertx/core/internal/ContextInternal.java
index 7d85f97b88c..0769169878d 100644
--- a/vertx-core/src/main/java/io/vertx/core/internal/ContextInternal.java
+++ b/vertx-core/src/main/java/io/vertx/core/internal/ContextInternal.java
@@ -36,7 +36,7 @@
  */
 public interface ContextInternal extends Context {
 
-  ContextLocal<ConcurrentMap<Object, Object>> LOCAL_MAP = new ContextLocalImpl<>(0);
+  ContextLocal<ConcurrentMap<Object, Object>> LOCAL_MAP = new ContextLocalImpl<>(0, ConcurrentHashMap::new);
 
   /**
    * @return the current context
diff --git a/vertx-core/src/main/java/io/vertx/core/internal/VertxInternal.java b/vertx-core/src/main/java/io/vertx/core/internal/VertxInternal.java
index 9ec4f47c3fe..52418b913da 100644
--- a/vertx-core/src/main/java/io/vertx/core/internal/VertxInternal.java
+++ b/vertx-core/src/main/java/io/vertx/core/internal/VertxInternal.java
@@ -23,6 +23,7 @@
 import io.vertx.core.net.NetServerOptions;
 import io.vertx.core.net.impl.NetServerInternal;
 import io.vertx.core.net.impl.ServerID;
+import io.vertx.core.spi.context.storage.ContextLocal;
 import io.vertx.core.spi.transport.Transport;
 import io.vertx.core.spi.cluster.ClusterManager;
 import io.vertx.core.spi.file.FileResolver;
@@ -33,6 +34,7 @@
 import java.lang.ref.Cleaner;
 import java.net.InetAddress;
 import java.net.InetSocketAddress;
+import java.util.List;
 import java.util.Map;
 import java.util.concurrent.Callable;
 import java.util.concurrent.ExecutorService;
@@ -305,6 +307,11 @@ default <T> Future<T> executeBlockingInternal(Callable<T> blockingCodeHandler) {
    */
   AddressResolverGroup<InetSocketAddress> nettyAddressResolverGroup();
 
+  /**
+   * @return an immutable list of this vertx instance context locals
+   */
+  List<ContextLocal<?>> contextLocals();
+
   BlockedThreadChecker blockedThreadChecker();
 
   CloseFuture closeFuture();
diff --git a/vertx-core/src/main/java/io/vertx/core/internal/VertxWrapper.java b/vertx-core/src/main/java/io/vertx/core/internal/VertxWrapper.java
index 83070c6a652..7ff9628959c 100644
--- a/vertx-core/src/main/java/io/vertx/core/internal/VertxWrapper.java
+++ b/vertx-core/src/main/java/io/vertx/core/internal/VertxWrapper.java
@@ -30,6 +30,7 @@
 import io.vertx.core.net.NetServerOptions;
 import io.vertx.core.net.impl.NetServerInternal;
 import io.vertx.core.net.impl.ServerID;
+import io.vertx.core.spi.context.storage.ContextLocal;
 import io.vertx.core.spi.transport.Transport;
 import io.vertx.core.shareddata.SharedData;
 import io.vertx.core.spi.VerticleFactory;
@@ -42,9 +43,9 @@
 import java.lang.ref.Cleaner;
 import java.net.InetAddress;
 import java.net.InetSocketAddress;
+import java.util.List;
 import java.util.Map;
 import java.util.Set;
-import java.util.concurrent.Callable;
 import java.util.concurrent.ExecutorService;
 import java.util.concurrent.TimeUnit;
 import java.util.function.Function;
@@ -385,6 +386,11 @@ public AddressResolverGroup<InetSocketAddress> nettyAddressResolverGroup() {
     return delegate.nettyAddressResolverGroup();
   }
 
+  @Override
+  public List<ContextLocal<?>> contextLocals() {
+    return delegate.contextLocals();
+  }
+
   @Override
   public BlockedThreadChecker blockedThreadChecker() {
     return delegate.blockedThreadChecker();
diff --git a/vertx-core/src/main/java/io/vertx/core/spi/context/storage/ContextLocal.java b/vertx-core/src/main/java/io/vertx/core/spi/context/storage/ContextLocal.java
index 6bd5fc64755..fcac862f993 100644
--- a/vertx-core/src/main/java/io/vertx/core/spi/context/storage/ContextLocal.java
+++ b/vertx-core/src/main/java/io/vertx/core/spi/context/storage/ContextLocal.java
@@ -14,6 +14,7 @@
 import io.vertx.core.internal.ContextInternal;
 import io.vertx.core.impl.ContextLocalImpl;
 
+import java.util.function.Function;
 import java.util.function.Supplier;
 
 /**
@@ -35,7 +36,16 @@ public interface ContextLocal<T> {
    * @return the context local storage
    */
   static <T> ContextLocal<T> registerLocal(Class<T> type) {
-    return new ContextLocalImpl<>();
+    return ContextLocalImpl.create(type, Function.identity());
+  }
+
+  /**
+   * Registers a context local storage.
+   *
+   * @return the context local storage
+   */
+  static <T> ContextLocal<T> registerLocal(Class<T> type, Function<T, T> duplicator) {
+    return ContextLocalImpl.create(type, duplicator);
   }
 
   /**
diff --git a/vertx-core/src/test/java/io/vertx/tests/context/ContextTest.java b/vertx-core/src/test/java/io/vertx/tests/context/ContextTest.java
index 63ee4551704..874e60eac1f 100644
--- a/vertx-core/src/test/java/io/vertx/tests/context/ContextTest.java
+++ b/vertx-core/src/test/java/io/vertx/tests/context/ContextTest.java
@@ -1204,4 +1204,27 @@ public void testInterruptTask(ContextInternal context, Consumer<Runnable> actor)
     assertTrue((System.currentTimeMillis() - now) < 2000);
     assertTrue(interrupted.get());
   }
+
+  @Test
+  public void testNestedDuplicate() {
+    ContextInternal ctx = ((ContextInternal) vertx.getOrCreateContext()).duplicate();
+    ctx.putLocal("foo", "bar");
+    Object expected = new Object();
+    ctx.putLocal(contextLocal, AccessMode.CONCURRENT, expected);
+    ContextInternal duplicate = ctx.duplicate();
+    assertEquals("bar", duplicate.getLocal("foo"));
+    assertEquals(expected, duplicate.getLocal(contextLocal));
+    ctx.removeLocal("foo");
+    ctx.removeLocal(contextLocal, AccessMode.CONCURRENT);
+    assertEquals("bar", duplicate.getLocal("foo"));
+    assertEquals(expected, duplicate.getLocal(contextLocal));
+  }
+
+  @Test
+  public void testContextLocals() {
+    List<ContextLocal<?>> locals = ((VertxInternal) vertx).contextLocals();
+    assertSame(ContextInternal.LOCAL_MAP, locals.get(0));
+    assertSame(contextLocal, locals.get(1));
+    assertSame(locals, ((VertxInternal) vertx).contextLocals());
+  }
 }