diff --git a/j2cl-tasks/pom.xml b/j2cl-tasks/pom.xml
index bc063eb2..022d7da9 100644
--- a/j2cl-tasks/pom.xml
+++ b/j2cl-tasks/pom.xml
@@ -95,4 +95,4 @@
             <scope>test</scope>
         </dependency>
     </dependencies>
-</project>
\ No newline at end of file
+</project>
diff --git a/j2cl-tasks/src/main/java/com/vertispan/j2cl/build/provided/BundleJarTask.java b/j2cl-tasks/src/main/java/com/vertispan/j2cl/build/provided/BundleJarTask.java
index ab383c36..a0916ca0 100644
--- a/j2cl-tasks/src/main/java/com/vertispan/j2cl/build/provided/BundleJarTask.java
+++ b/j2cl-tasks/src/main/java/com/vertispan/j2cl/build/provided/BundleJarTask.java
@@ -113,13 +113,6 @@ public void finish(TaskContext taskContext) throws IOException {
                     Files.copy(bundle.getAbsolutePath(), targetFile, StandardCopyOption.REPLACE_EXISTING);
                 }
 
-                File destSourcesDir = outputDir.toPath().resolve(Closure.SOURCES_DIRECTORY_NAME).toFile();
-                destSourcesDir.mkdirs();
-                for (Path dir : jsSources.stream().map(Input::getParentPaths).flatMap(Collection::stream).map(p -> p.resolve(Closure
-                        .SOURCES_DIRECTORY_NAME)).collect(Collectors.toSet())) {
-                    FileUtils.copyDirectory(dir.toFile(), destSourcesDir);
-                }
-
                 try {
                     Gson gson = new GsonBuilder().setPrettyPrinting().create();
                     String scriptsArray = gson.toJson(sourceOrder.stream()
diff --git a/j2cl-tasks/src/main/java/com/vertispan/j2cl/build/provided/ClosureBundleTask.java b/j2cl-tasks/src/main/java/com/vertispan/j2cl/build/provided/ClosureBundleTask.java
index a951891e..2c2d2ed6 100644
--- a/j2cl-tasks/src/main/java/com/vertispan/j2cl/build/provided/ClosureBundleTask.java
+++ b/j2cl-tasks/src/main/java/com/vertispan/j2cl/build/provided/ClosureBundleTask.java
@@ -132,6 +132,7 @@ public Task resolve(Project project, Config config) {
                     depInfoMap = deps.stream()
                             .map(info -> new DependencyInfoAndSource(
                                     info,
+                                    fileNameKey,
                                     () -> Files.readString(lastOutput.resolve(Closure.SOURCES_DIRECTORY_NAME).resolve(info.getName())))
                             )
                             .collect(Collectors.toMap(DependencyInfo::getName, Function.identity()));
@@ -151,7 +152,7 @@ public Task resolve(Project project, Config config) {
                             input.setCompiler(jsCompiler);
                             depInfoMap.put(
                                     change.getSourcePath().toString(),
-                                    new DependencyInfoAndSource(input, input::getCode)
+                                    new DependencyInfoAndSource(input, fileNameKey, input::getCode)
                             );
                         }
                     }
@@ -170,8 +171,7 @@ public Task resolve(Project project, Config config) {
                                 .withOriginalPath(path.getSourcePath().toString())
                                 .build());
                         input.setCompiler(jsCompiler);
-
-                        dependencyInfos.add(new DependencyInfoAndSource(input, input::getCode));
+                        dependencyInfos.add(new DependencyInfoAndSource(input, fileNameKey, input::getCode));
                     }
                 }
             }
@@ -202,6 +202,7 @@ public Task resolve(Project project, Config config) {
                 for (DependencyInfoAndSource info : sorter.getSortedList()) {
                     String code = info.getSource();
                     String name = info.getName();
+                    String projectName = info.getProject();
 
                     //TODO do we actually need this?
                     if (Compiler.isFillFileName(name) && code.isEmpty()) {
@@ -210,7 +211,7 @@ public Task resolve(Project project, Config config) {
 
                     // append this file and a comment where it came from
                     bundleOut.append("//").append(name).append("\n");
-                    bundler.withPath(name).withSourceUrl(Closure.SOURCES_DIRECTORY_NAME + "/" + name).appendTo(bundleOut, info, code);
+                    bundler.withPath(name).withSourceUrl(Closure.SOURCES_DIRECTORY_NAME + "/" + projectName + "/" + name).appendTo(bundleOut, info, code);
                     bundleOut.append("\n");
 
                 }
@@ -245,8 +246,11 @@ public static class DependencyInfoAndSource implements DependencyInfo {
         private final DependencyInfo delegate;
         private final SourceSupplier sourceSupplier;
 
-        public DependencyInfoAndSource(DependencyInfo delegate, SourceSupplier sourceSupplier) {
+        private final String project;
+
+        public DependencyInfoAndSource(DependencyInfo delegate, String project, SourceSupplier sourceSupplier) {
             this.delegate = delegate;
+            this.project = project.replaceAll("\\.", "-");
             this.sourceSupplier = sourceSupplier;
         }
 
@@ -309,6 +313,10 @@ public boolean getHasExternsAnnotation() {
         public boolean getHasNoCompileAnnotation() {
             return delegate.getHasNoCompileAnnotation();
         }
+
+        public String getProject() {
+            return project;
+        }
     }
 
     public static class DependencyInfoFormat implements DependencyInfo {
diff --git a/j2cl-tasks/src/main/java/com/vertispan/j2cl/build/provided/J2clTask.java b/j2cl-tasks/src/main/java/com/vertispan/j2cl/build/provided/J2clTask.java
index bd3b87ec..e1d42cea 100644
--- a/j2cl-tasks/src/main/java/com/vertispan/j2cl/build/provided/J2clTask.java
+++ b/j2cl-tasks/src/main/java/com/vertispan/j2cl/build/provided/J2clTask.java
@@ -2,10 +2,15 @@
 
 import com.google.auto.service.AutoService;
 import com.google.j2cl.common.SourceUtils;
+import com.google.javascript.jscomp.CompilationLevel;
 import com.vertispan.j2cl.build.task.*;
+import com.vertispan.j2cl.tools.Closure;
 import com.vertispan.j2cl.tools.J2cl;
+import org.apache.commons.io.FileUtils;
 
 import java.io.File;
+import java.io.IOException;
+import java.nio.file.Files;
 import java.nio.file.Path;
 import java.nio.file.PathMatcher;
 import java.util.Collections;
@@ -51,6 +56,11 @@ public Task resolve(Project project, Config config) {
 
         File bootstrapClasspath = config.getBootstrapClasspath();
         List<File> extraClasspath = config.getExtraClasspath();
+
+        //*******
+        boolean sourcemapsEnabled = config.getSourcemapsEnabled();
+        Path sourceMapsFolder = sourcemapsEnabled ? prepareSourcesFolder(config, project) : null;
+
         return context -> {
             if (ownJavaSources.getFilesAndHashes().isEmpty()) {
                 return;// nothing to do
@@ -82,6 +92,28 @@ public Task resolve(Project project, Config config) {
             if (!j2cl.transpile(javaSources, nativeSources)) {
                 throw new IllegalStateException("Error while running J2CL");
             }
+
+            if(sourcemapsEnabled) {
+                if(sourceMapsFolder.toFile().exists()) {
+                    FileUtils.deleteDirectory(sourceMapsFolder.toFile());
+                }
+                sourceMapsFolder.toFile().mkdirs();
+                FileUtils.copyDirectory(context.outputPath().toFile(), sourceMapsFolder.toFile());
+            }
         };
     }
+
+    private Path prepareSourcesFolder(Config config, Project project) {
+        try {
+            Path initialScriptFile = config.getWebappDirectory().resolve(config.getInitialScriptFilename());
+            Path outputDir = initialScriptFile.getParent();
+            Files.createDirectories(outputDir);
+            Path destSourcesDir = outputDir.resolve(Closure.SOURCES_DIRECTORY_NAME);
+            Files.createDirectories(destSourcesDir);
+            Path dist = destSourcesDir.resolve(project.getKey().replaceAll("\\.","-").replaceAll(":","-"));
+            return dist;
+        } catch (IOException e) {
+            throw new RuntimeException(e);
+        }
+    }
 }