diff --git a/dev/tools/localization/bin/gen_l10n.dart b/dev/tools/localization/bin/gen_l10n.dart
index 768b5f0d9de..195b860c800 100644
--- a/dev/tools/localization/bin/gen_l10n.dart
+++ b/dev/tools/localization/bin/gen_l10n.dart
@@ -105,6 +105,21 @@ void main(List<String> arguments) {
       'Note that this flag does not affect other platforms such as mobile or '
       'desktop.',
   );
+  parser.addOption(
+    'gen-inputs-and-outputs-list',
+    valueHelp: 'path-to-output-directory',
+    help: 'When specified, the tool generates a JSON file containing the '
+      'tool\'s inputs and outputs named gen_l10n_inputs_and_outputs.json.'
+      '\n\n'
+      'This can be useful for keeping track of which files of the Flutter '
+      'project were used when generating the latest set of localizations. '
+      'For example, the Flutter tool\'s build system uses this file to '
+      'keep track of when to call gen_l10n during hot reload.\n\n'
+      'The value of this option is the directory where the JSON file will be '
+      'generated.'
+      '\n\n'
+      'When null, the JSON file will not be generated.'
+  );
 
   final argslib.ArgResults results = parser.parse(arguments);
   if (results['help'] == true) {
@@ -124,6 +139,7 @@ void main(List<String> arguments) {
   final String headerString = results['header'] as String;
   final String headerFile = results['header-file'] as String;
   final bool useDeferredLoading = results['use-deferred-loading'] as bool;
+  final String inputsAndOutputsListPath = results['gen-inputs-and-outputs-list'] as String;
 
   const local.LocalFileSystem fs = local.LocalFileSystem();
   final LocalizationsGenerator localizationsGenerator = LocalizationsGenerator(fs);
@@ -140,9 +156,10 @@ void main(List<String> arguments) {
         headerString: headerString,
         headerFile: headerFile,
         useDeferredLoading: useDeferredLoading,
+        inputsAndOutputsListPath: inputsAndOutputsListPath,
       )
       ..loadResources()
-      ..writeOutputFile()
+      ..writeOutputFiles()
       ..outputUnimplementedMessages(untranslatedMessagesFile);
   } on FileSystemException catch (e) {
     exitWithError(e.message);
diff --git a/dev/tools/localization/gen_l10n.dart b/dev/tools/localization/gen_l10n.dart
index 0aba4b853c6..dfab847ec73 100644
--- a/dev/tools/localization/gen_l10n.dart
+++ b/dev/tools/localization/gen_l10n.dart
@@ -418,11 +418,13 @@ class LocalizationsGenerator {
   /// This file is specified with the [initialize] method.
   File templateArbFile;
 
-  /// The file to write the generated localizations and localizations delegate
-  /// classes to.
+  /// The file to write the generated abstract localizations and
+  /// localizations delegate classes to. Separate localizations
+  /// files will also be generated for each language using this
+  /// filename as a prefix and the locale as the suffix.
   ///
   /// This file is specified with the [initialize] method.
-  File outputFile;
+  File baseOutputFile;
 
   /// The class name to be used for the localizations class in [outputFile].
   ///
@@ -491,6 +493,12 @@ class LocalizationsGenerator {
   /// classes.
   String _generatedLocalizationsFile;
 
+  /// The file that contains the list of inputs and outputs for generating
+  /// localizations.
+  File _inputsAndOutputsListFile;
+  List<String> _inputFileList;
+  List<String> _outputFileList;
+
   /// Initializes [inputDirectory], [outputDirectory], [templateArbFile],
   /// [outputFile] and [className].
   ///
@@ -509,15 +517,17 @@ class LocalizationsGenerator {
     String headerString,
     String headerFile,
     bool useDeferredLoading = false,
+    String inputsAndOutputsListPath,
   }) {
     setInputDirectory(inputPathString);
     setOutputDirectory(outputPathString ?? inputPathString);
     setTemplateArbFile(templateArbFileName);
-    setOutputFile(outputFileString);
+    setBaseOutputFile(outputFileString);
     setPreferredSupportedLocales(preferredSupportedLocaleString);
     _setHeader(headerString, headerFile);
     _setUseDeferredLoading(useDeferredLoading);
     className = classNameString;
+    _setInputsAndOutputsListFile(inputsAndOutputsListPath);
   }
 
   static bool _isNotReadable(FileStat fileStat) {
@@ -581,10 +591,10 @@ class LocalizationsGenerator {
 
   /// Sets the reference [File] for the localizations delegate [outputFile].
   @visibleForTesting
-  void setOutputFile(String outputFileString) {
+  void setBaseOutputFile(String outputFileString) {
     if (outputFileString == null)
       throw L10nException('outputFileString argument cannot be null');
-    outputFile = _fs.file(path.join(outputDirectory.path, outputFileString));
+    baseOutputFile = _fs.file(path.join(outputDirectory.path, outputFileString));
   }
 
   static bool _isValidClassName(String className) {
@@ -664,6 +674,17 @@ class LocalizationsGenerator {
     _useDeferredLoading = useDeferredLoading;
   }
 
+  void _setInputsAndOutputsListFile(String inputsAndOutputsListPath) {
+    if (inputsAndOutputsListPath == null)
+      return;
+
+    _inputsAndOutputsListFile = _fs.file(
+      path.join(inputsAndOutputsListPath, 'gen_l10n_inputs_and_outputs.json'),
+    );
+    _inputFileList = <String>[];
+    _outputFileList = <String>[];
+  }
+
   static bool _isValidGetterAndMethodName(String name) {
     // Public Dart method name must not start with an underscore
     if (name[0] == '_')
@@ -697,6 +718,11 @@ class LocalizationsGenerator {
       }
 
     _allBundles = AppResourceBundleCollection(inputDirectory);
+    if (_inputsAndOutputsListFile != null) {
+      _inputFileList.addAll(_allBundles.bundles.map((AppResourceBundle bundle) {
+        return bundle.file.absolute.path;
+      }));
+    }
 
     final List<LocaleInfo> allLocales = List<LocaleInfo>.from(_allBundles.locales);
     for (final LocaleInfo preferredLocale in preferredSupportedLocales) {
@@ -781,8 +807,9 @@ class LocalizationsGenerator {
   }
 
   // Generate the AppLocalizations class, its LocalizationsDelegate subclass,
-  // and all AppLocalizations subclasses for every locale.
-  void generateCode() {
+  // and all AppLocalizations subclasses for every locale. This method by
+  // itself does not generate the output files.
+  void _generateCode() {
     bool isBaseClassLocale(LocaleInfo locale, String language) {
       return locale.languageCode == language
           && locale.countryCode == null
@@ -800,7 +827,7 @@ class LocalizationsGenerator {
     }
 
     final String directory = path.basename(outputDirectory.path);
-    final String outputFileName = path.basename(outputFile.path);
+    final String outputFileName = path.basename(baseOutputFile.path);
 
     final Iterable<String> supportedLocalesCode = supportedLocales.map((LocaleInfo locale) {
       final String languageCode = locale.languageCode;
@@ -892,9 +919,9 @@ class LocalizationsGenerator {
       .replaceAll('@(delegateClass)', delegateClass);
   }
 
-  void writeOutputFile() {
+  void writeOutputFiles() {
     // First, generate the string contents of all necessary files.
-    generateCode();
+    _generateCode();
 
     // Since all validity checks have passed up to this point,
     // write the contents into the directory.
@@ -913,8 +940,27 @@ class LocalizationsGenerator {
     // Generate the required files for localizations.
     _languageFileMap.forEach((File file, String contents) {
       file.writeAsStringSync(contents);
+      if (_inputsAndOutputsListFile != null) {
+        _outputFileList.add(file.absolute.path);
+      }
     });
-    outputFile.writeAsStringSync(_generatedLocalizationsFile);
+
+    baseOutputFile.writeAsStringSync(_generatedLocalizationsFile);
+    if (_inputsAndOutputsListFile != null) {
+      _outputFileList.add(baseOutputFile.absolute.path);
+
+      // Generate a JSON file containing the inputs and outputs of the gen_l10n script.
+      if (!_inputsAndOutputsListFile.existsSync()) {
+        _inputsAndOutputsListFile.createSync(recursive: true);
+      }
+
+      _inputsAndOutputsListFile.writeAsStringSync(
+        json.encode(<String, Object> {
+          'inputs': _inputFileList,
+          'outputs': _outputFileList,
+        }),
+      );
+    }
   }
 
   void outputUnimplementedMessages(String untranslatedMessagesFile) {
diff --git a/dev/tools/test/localization/gen_l10n_test.dart b/dev/tools/test/localization/gen_l10n_test.dart
index 21a14f8c124..8748a221c1f 100644
--- a/dev/tools/test/localization/gen_l10n_test.dart
+++ b/dev/tools/test/localization/gen_l10n_test.dart
@@ -77,7 +77,7 @@ void main() {
       }
 
       fail(
-        'Attempting to set LocalizationsGenerator.setInputDirectory should fail if the '
+        'LocalizationsGenerator.setInputDirectory should fail if the '
         'directory does not exist.'
       );
     });
@@ -93,8 +93,8 @@ void main() {
       }
 
       fail(
-        'Attempting to set LocalizationsGenerator.setInputDirectory should fail if the '
-        'the input string is null.'
+        'LocalizationsGenerator.setInputDirectory should fail if the '
+        'input string is null.'
       );
     });
 
@@ -109,8 +109,8 @@ void main() {
       }
 
       fail(
-        'Attempting to set LocalizationsGenerator.setOutputDirectory should fail if the '
-        'the input string is null.'
+        'LocalizationsGenerator.setOutputDirectory should fail if the '
+        'input string is null.'
       );
     });
 
@@ -124,8 +124,8 @@ void main() {
       }
 
       fail(
-        'Attempting to set LocalizationsGenerator.setTemplateArbFile should fail if the '
-        'the inputDirectory is not specified.'
+        'LocalizationsGenerator.setTemplateArbFile should fail if the '
+        'inputDirectory is not specified.'
       );
     });
 
@@ -140,8 +140,8 @@ void main() {
       }
 
       fail(
-        'Attempting to set LocalizationsGenerator.setTemplateArbFile should fail if the '
-        'the templateArbFileName passed in is null.'
+        'LocalizationsGenerator.setTemplateArbFile should fail if the '
+        'templateArbFileName passed in is null.'
       );
     });
 
@@ -156,24 +156,24 @@ void main() {
       }
 
       fail(
-        'Attempting to set LocalizationsGenerator.setTemplateArbFile should fail if the '
-        'the input string is null.'
+        'LocalizationsGenerator.setTemplateArbFile should fail if the '
+        'input string is null.'
       );
     });
 
-    test('setOutputFile fails if input string is null', () {
+    test('setBaseOutputFile fails if input string is null', () {
       _standardFlutterDirectoryL10nSetup(fs);
       final LocalizationsGenerator generator = LocalizationsGenerator(fs);
       try {
-        generator.setOutputFile(null);
+        generator.setBaseOutputFile(null);
       } on L10nException catch (e) {
         expect(e.message, contains('cannot be null'));
         return;
       }
 
       fail(
-        'Attempting to set LocalizationsGenerator.setOutputFile should fail if the '
-        'the input string is null.'
+        'LocalizationsGenerator.setBaseOutputFile should fail if the '
+        'input string is null.'
       );
     });
 
@@ -188,8 +188,8 @@ void main() {
       }
 
       fail(
-        'Attempting to set LocalizationsGenerator.className should fail if the '
-        'the input string is null.'
+        'LocalizationsGenerator.className should fail if the '
+        'input string is null.'
       );
     });
 
@@ -202,7 +202,7 @@ void main() {
           generator.setInputDirectory(defaultL10nPathString);
           generator.setOutputDirectory(defaultL10nPathString);
           generator.setTemplateArbFile(defaultTemplateArbFileName);
-          generator.setOutputFile(defaultOutputFileString);
+          generator.setBaseOutputFile(defaultOutputFileString);
         } on L10nException catch (e) {
           throw TestFailure('Unexpected failure during test setup: ${e.message}');
         }
@@ -216,8 +216,8 @@ void main() {
           return;
         }
         fail(
-          'Attempting to set LocalizationsGenerator.className should fail if the '
-          'the input string is not a valid Dart class name.'
+          'LocalizationsGenerator.className should fail if the '
+          'input string is not a valid Dart class name.'
         );
       });
 
@@ -229,8 +229,8 @@ void main() {
           return;
         }
         fail(
-          'Attempting to set LocalizationsGenerator.className should fail if the '
-          'the input string is not a valid public Dart class name.'
+          'LocalizationsGenerator.className should fail if the '
+          'input string is not a valid public Dart class name.'
         );
       });
 
@@ -242,8 +242,8 @@ void main() {
           return;
         }
         fail(
-          'Attempting to set LocalizationsGenerator.className should fail if the '
-          'the input string is not a valid public Dart class name.'
+          'LocalizationsGenerator.className should fail if the '
+          'input string is not a valid public Dart class name.'
         );
       });
 
@@ -255,8 +255,8 @@ void main() {
           return;
         }
         fail(
-          'Attempting to set LocalizationsGenerator.className should fail if the '
-          'the input string is not a valid public Dart class name.'
+          'LocalizationsGenerator.className should fail if the '
+          'input string is not a valid public Dart class name.'
         );
       });
     });
@@ -326,7 +326,7 @@ void main() {
           classNameString: defaultClassNameString,
         )
         ..loadResources()
-        ..generateCode()
+        ..writeOutputFiles()
         ..outputUnimplementedMessages(path.join('lib', 'l10n', 'unimplemented_message_translations.json'));
     } on L10nException catch (e) {
       fail('Generating output should not fail: \n${e.message}');
@@ -359,7 +359,7 @@ void main() {
           classNameString: defaultClassNameString,
         )
         ..loadResources()
-        ..writeOutputFile();
+        ..writeOutputFiles();
     } on L10nException catch (e) {
       fail('Generating output should not fail: \n${e.message}');
     }
@@ -397,7 +397,7 @@ void main() {
           classNameString: defaultClassNameString,
         )
         ..loadResources()
-        ..writeOutputFile();
+        ..writeOutputFiles();
     } on L10nException catch (e) {
       fail('Generating output should not fail: \n${e.message}');
     }
@@ -424,7 +424,7 @@ void main() {
           classNameString: defaultClassNameString,
         )
         ..loadResources()
-        ..writeOutputFile();
+        ..writeOutputFiles();
     } on L10nException catch (e) {
       fail('Generating output should not fail: \n${e.message}');
     }
@@ -436,6 +436,45 @@ void main() {
     expect(outputDirectory.childFile('output-localization-file_es.dart').existsSync(), isTrue);
   });
 
+  test('creates list of inputs and outputs when file path is specified', () {
+    _standardFlutterDirectoryL10nSetup(fs);
+
+    LocalizationsGenerator generator;
+    try {
+      generator = LocalizationsGenerator(fs);
+      generator
+        ..initialize(
+          inputPathString: defaultL10nPathString,
+          templateArbFileName: defaultTemplateArbFileName,
+          outputFileString: defaultOutputFileString,
+          classNameString: defaultClassNameString,
+          inputsAndOutputsListPath: defaultL10nPathString,
+        )
+        ..loadResources()
+        ..writeOutputFiles();
+    } on L10nException catch (e) {
+      fail('Generating output should not fail: \n${e.message}');
+    }
+
+    final File inputsAndOutputsList = fs
+      .directory('lib')
+      .childDirectory('l10n')
+      .childFile('gen_l10n_inputs_and_outputs.json');
+    expect(inputsAndOutputsList.existsSync(), isTrue);
+
+    final Map<String, dynamic> jsonResult = json.decode(inputsAndOutputsList.readAsStringSync()) as Map<String, dynamic>;
+    expect(jsonResult.containsKey('inputs'), isTrue);
+    final List<dynamic> inputList = jsonResult['inputs'] as List<dynamic>;
+    expect(inputList, contains(fs.path.absolute('lib', 'l10n', 'app_en.arb')));
+    expect(inputList, contains(fs.path.absolute('lib', 'l10n', 'app_es.arb')));
+
+    expect(jsonResult.containsKey('outputs'), isTrue);
+    final List<dynamic> outputList = jsonResult['outputs'] as List<dynamic>;
+    expect(outputList, contains(fs.path.absolute('lib', 'l10n', 'output-localization-file.dart')));
+    expect(outputList, contains(fs.path.absolute('lib', 'l10n', 'output-localization-file_en.dart')));
+    expect(outputList, contains(fs.path.absolute('lib', 'l10n', 'output-localization-file_es.dart')));
+  });
+
   test('setting both a headerString and a headerFile should fail', () {
     fs.currentDirectory.childDirectory('lib').childDirectory('l10n')
       ..createSync(recursive: true)
@@ -710,15 +749,9 @@ void main() {
         fail('Setting language and locales should not fail: \n${e.message}');
       }
 
-      if (Platform.isWindows) {
-        expect(generator.arbPathStrings.first, r'lib\l10n\app_en.arb');
-        expect(generator.arbPathStrings.elementAt(1), r'lib\l10n\app_es.arb');
-        expect(generator.arbPathStrings.elementAt(2), r'lib\l10n\app_zh.arb');
-      } else {
-        expect(generator.arbPathStrings.first, 'lib/l10n/app_en.arb');
-        expect(generator.arbPathStrings.elementAt(1), 'lib/l10n/app_es.arb');
-        expect(generator.arbPathStrings.elementAt(2), 'lib/l10n/app_zh.arb');
-      }
+      expect(generator.arbPathStrings.first, path.join('lib', 'l10n', 'app_en.arb'));
+      expect(generator.arbPathStrings.elementAt(1), path.join('lib', 'l10n', 'app_es.arb'));
+      expect(generator.arbPathStrings.elementAt(2), path.join('lib', 'l10n', 'app_zh.arb'));
     });
 
     test('correctly parses @@locale property in arb file', () {
@@ -904,7 +937,7 @@ void main() {
     });
   });
 
-  group('generateCode', () {
+  group('writeOutputFiles', () {
     test('should generate a file per language', () {
       const String singleEnCaMessageArbFileString = '''
 {
@@ -924,7 +957,7 @@ void main() {
           classNameString: defaultClassNameString,
         );
         generator.loadResources();
-        generator.writeOutputFile();
+        generator.writeOutputFiles();
       } on Exception catch (e) {
         fail('Generating output files should not fail: $e');
       }
@@ -957,7 +990,7 @@ void main() {
           preferredSupportedLocaleString: preferredSupportedLocaleString,
         );
         generator.loadResources();
-        generator.writeOutputFile();
+        generator.writeOutputFiles();
       } on Exception catch (e) {
         fail('Generating output files should not fail: $e');
       }
@@ -988,7 +1021,7 @@ import 'output-localization-file_zh.dart';
           useDeferredLoading: true,
         );
         generator.loadResources();
-        generator.writeOutputFile();
+        generator.writeOutputFiles();
       } on Exception catch (e) {
         fail('Generating output files should not fail: $e');
       }
@@ -1033,7 +1066,7 @@ import 'output-localization-file_en.dart' deferred as output-localization-file_e
             classNameString: defaultClassNameString,
           );
           generator.loadResources();
-          generator.generateCode();
+          generator.writeOutputFiles();
         } on L10nException catch (e) {
           expect(e.message, contains('asdf'));
           expect(e.message, contains('springStartDate'));
@@ -1072,7 +1105,7 @@ import 'output-localization-file_en.dart' deferred as output-localization-file_e
             classNameString: defaultClassNameString,
           );
           generator.loadResources();
-          generator.generateCode();
+          generator.writeOutputFiles();
         } on L10nException catch (e) {
           expect(e.message, contains('the "format" attribute needs to be set'));
           return;
@@ -1110,7 +1143,7 @@ import 'output-localization-file_en.dart' deferred as output-localization-file_e
             classNameString: defaultClassNameString,
           );
           generator.loadResources();
-          generator.generateCode();
+          generator.writeOutputFiles();
         } on L10nException catch (e) {
           expect(e.message, contains('asdf'));
           expect(e.message, contains('progress'));
@@ -1147,7 +1180,7 @@ import 'output-localization-file_en.dart' deferred as output-localization-file_e
             classNameString: defaultClassNameString,
           );
           generator.loadResources();
-          generator.generateCode();
+          generator.writeOutputFiles();
         } on L10nException catch (e) {
           expect(e.message, contains('Check to see if the plural message is in the proper ICU syntax format'));
           return;
@@ -1180,7 +1213,7 @@ import 'output-localization-file_en.dart' deferred as output-localization-file_e
             classNameString: defaultClassNameString,
           );
           generator.loadResources();
-          generator.generateCode();
+          generator.writeOutputFiles();
         } on L10nException catch (e) {
           expect(e.message, contains('Check to see if the plural message is in the proper ICU syntax format'));
           return;
@@ -1209,7 +1242,7 @@ import 'output-localization-file_en.dart' deferred as output-localization-file_e
             classNameString: defaultClassNameString,
           );
           generator.loadResources();
-          generator.generateCode();
+          generator.writeOutputFiles();
         } on L10nException catch (e) {
           expect(e.message, contains('Resource attribute "@helloWorlds" was not found'));
           return;
@@ -1241,7 +1274,7 @@ import 'output-localization-file_en.dart' deferred as output-localization-file_e
             classNameString: defaultClassNameString,
           );
           generator.loadResources();
-          generator.generateCode();
+          generator.writeOutputFiles();
         } on L10nException catch (e) {
           expect(e.message, contains('is not properly formatted'));
           expect(e.message, contains('Ensure that it is a map with string valued keys'));
@@ -1274,7 +1307,7 @@ import 'output-localization-file_en.dart' deferred as output-localization-file_e
           classNameString: defaultClassNameString,
         );
         generator.loadResources();
-        generator.generateCode();
+        generator.writeOutputFiles();
       } on FormatException catch (e) {
         expect(e.message, contains('Unexpected character'));
         return;
@@ -1306,7 +1339,7 @@ import 'output-localization-file_en.dart' deferred as output-localization-file_e
           classNameString: defaultClassNameString,
         );
         generator.loadResources();
-        generator.generateCode();
+        generator.writeOutputFiles();
       } on L10nException catch (e) {
         expect(e.message, contains('Resource attribute "@title" was not found'));
         return;
@@ -1342,7 +1375,7 @@ import 'output-localization-file_en.dart' deferred as output-localization-file_e
             classNameString: defaultClassNameString,
           );
           generator.loadResources();
-          generator.generateCode();
+          generator.writeOutputFiles();
         } on L10nException catch (e) {
           expect(e.message, contains('Invalid ARB resource name'));
           return;
@@ -1374,7 +1407,7 @@ import 'output-localization-file_en.dart' deferred as output-localization-file_e
             classNameString: defaultClassNameString,
           );
           generator.loadResources();
-          generator.generateCode();
+          generator.writeOutputFiles();
         } on L10nException catch (e) {
           expect(e.message, contains('Invalid ARB resource name'));
           return;
@@ -1406,7 +1439,7 @@ import 'output-localization-file_en.dart' deferred as output-localization-file_e
             classNameString: defaultClassNameString,
           );
           generator.loadResources();
-          generator.generateCode();
+          generator.writeOutputFiles();
         } on L10nException catch (e) {
           expect(e.message, contains('Invalid ARB resource name'));
           return;