diff --git a/src/main/java/com/formdev/flatlaf/intellijthemes/IJThemesDuplicateNameChecker.java b/src/main/java/com/formdev/flatlaf/intellijthemes/IJThemesDuplicateNameChecker.java
new file mode 100644
index 0000000..8dda871
--- /dev/null
+++ b/src/main/java/com/formdev/flatlaf/intellijthemes/IJThemesDuplicateNameChecker.java
@@ -0,0 +1,72 @@
+/*
+ * Copyright 2021 FormDev Software GmbH
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.formdev.flatlaf.intellijthemes;
+
+import java.io.FileInputStream;
+import java.io.IOException;
+import java.io.InputStreamReader;
+import java.io.Reader;
+import java.nio.charset.StandardCharsets;
+import java.util.HashSet;
+import java.util.Map;
+import com.formdev.flatlaf.json.Json;
+import com.formdev.flatlaf.json.ParseException;
+
+/**
+ * This tool checks whether there are duplicate name fields in all theme .json files.
+ *
+ * This is important for following file, where the name is used for theme specific UI defaults:
+ *   flatlaf-core/src/main/resources/com/formdev/flatlaf/IntelliJTheme$ThemeLaf.properties
+ *
+ * @author Karl Tauber
+ */
+public class IJThemesDuplicateNameChecker
+{
+	public static void main( String[] args ) {
+		IJThemesManager themesManager = new IJThemesManager();
+		themesManager.loadBundledThemes();
+
+		HashSet<String> names = new HashSet<>();
+		for( IJThemeInfo ti : themesManager.bundledThemes ) {
+			if( ti.sourceCodeUrl == null || ti.sourceCodePath == null )
+				continue;
+
+			String jsonPath = "../flatlaf-intellij-themes/src/main/resources" + IJThemesPanel.THEMES_PACKAGE + ti.resourceName;
+			String name;
+			try {
+				name = readNameFromJson( jsonPath );
+			} catch( IOException ex ) {
+				System.err.println( "Failed to read '" + jsonPath + "'" );
+				continue;
+			}
+
+			if( names.contains( name ) )
+				System.out.println( "Duplicate name '" + name + "'" );
+			names.add( name );
+		}
+	}
+
+	private static String readNameFromJson( String jsonPath ) throws IOException {
+		try( Reader reader = new InputStreamReader( new FileInputStream( jsonPath ), StandardCharsets.UTF_8 ) ) {
+			@SuppressWarnings( "unchecked" )
+			Map<String, Object> json = (Map<String, Object>) Json.parse( reader );
+			return (String) json.get( "name" );
+		} catch( ParseException ex ) {
+			throw new IOException( ex.getMessage(), ex );
+		}
+	}
+}
diff --git a/src/main/java/com/formdev/flatlaf/intellijthemes/IJThemesManager.java b/src/main/java/com/formdev/flatlaf/intellijthemes/IJThemesManager.java
new file mode 100644
index 0000000..095fa9e
--- /dev/null
+++ b/src/main/java/com/formdev/flatlaf/intellijthemes/IJThemesManager.java
@@ -0,0 +1,104 @@
+/*
+ * Copyright 2019 FormDev Software GmbH
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.formdev.flatlaf.intellijthemes;
+
+import java.io.File;
+import java.io.IOException;
+import java.io.InputStreamReader;
+import java.io.Reader;
+import java.nio.charset.StandardCharsets;
+import java.util.ArrayList;
+import java.util.HashMap;
+import java.util.List;
+import java.util.Map;
+import com.formdev.flatlaf.json.Json;
+import com.formdev.flatlaf.util.LoggingFacade;
+import com.formdev.flatlaf.util.StringUtils;
+
+/**
+ * @author Karl Tauber
+ */
+class IJThemesManager
+{
+	final List<IJThemeInfo> bundledThemes = new ArrayList<>();
+	final List<IJThemeInfo> moreThemes = new ArrayList<>();
+	private final Map<File,Long> lastModifiedMap = new HashMap<>();
+
+	@SuppressWarnings( "unchecked" )
+	void loadBundledThemes() {
+		bundledThemes.clear();
+
+		// load themes.json
+		Map<String, Object> json;
+	    try( Reader reader = new InputStreamReader( getClass().getResourceAsStream( "themes.json" ), StandardCharsets.UTF_8 ) ) {
+	    		json = (Map<String, Object>) Json.parse( reader );
+		} catch( IOException ex ) {
+			LoggingFacade.INSTANCE.logSevere( null, ex );
+			return;
+		}
+
+		// add info about bundled themes
+		for( Map.Entry<String, Object> e : json.entrySet() ) {
+			String resourceName = e.getKey();
+			Map<String, String> value = (Map<String, String>) e.getValue();
+			String name = value.get( "name" );
+			boolean discontinued = Boolean.parseBoolean( value.get( "discontinued" ) );
+			boolean dark = Boolean.parseBoolean( value.get( "dark" ) );
+			String lafClassName = value.get( "lafClassName" );
+			String license = value.get( "license" );
+			String licenseFile = value.get( "licenseFile" );
+			String pluginUrl = value.get( "pluginUrl" );
+			String sourceCodeUrl = value.get( "sourceCodeUrl" );
+			String sourceCodePath = value.get( "sourceCodePath" );
+
+			bundledThemes.add( new IJThemeInfo( name, resourceName, discontinued, dark,
+				license, licenseFile, pluginUrl, sourceCodeUrl, sourceCodePath, null, lafClassName ) );
+		}
+	}
+
+	void loadThemesFromDirectory() {
+		// get current working directory
+		File directory = new File( "" ).getAbsoluteFile();
+
+		File[] themeFiles = directory.listFiles( (dir, name) -> {
+			return name.endsWith( ".theme.json" ) || name.endsWith( ".properties" );
+		} );
+		if( themeFiles == null )
+			return;
+
+		lastModifiedMap.clear();
+		lastModifiedMap.put( directory, directory.lastModified() );
+
+		moreThemes.clear();
+		for( File f : themeFiles ) {
+			String fname = f.getName();
+			String name = fname.endsWith( ".properties" )
+				? StringUtils.removeTrailing( fname, ".properties" )
+				: StringUtils.removeTrailing( fname, ".theme.json" );
+			moreThemes.add( new IJThemeInfo( name, null, false, false, null, null, null, null, null, f, null ) );
+			lastModifiedMap.put( f, f.lastModified() );
+		}
+	}
+
+	boolean hasThemesFromDirectoryChanged() {
+		for( Map.Entry<File, Long> e : lastModifiedMap.entrySet() ) {
+			if( e.getKey().lastModified() != e.getValue().longValue() )
+				return true;
+		}
+		return false;
+	}
+}