diff --git a/webdev/lib/src/command/daemon_command.dart b/webdev/lib/src/command/daemon_command.dart
new file mode 100644
index 000000000..e2df6e2a8
--- /dev/null
+++ b/webdev/lib/src/command/daemon_command.dart
@@ -0,0 +1,49 @@
+// Copyright (c) 2019, the Dart project authors.  Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+import 'dart:async';
+import 'dart:convert';
+import 'dart:io';
+
+import 'package:args/command_runner.dart';
+
+import '../daemon/daemon.dart';
+
+Stream<Map<String, dynamic>> get _stdinCommandStream => stdin
+        .transform<String>(utf8.decoder)
+        .transform<String>(const LineSplitter())
+        .where((String line) => line.startsWith('[{') && line.endsWith('}]'))
+        .map<Map<String, dynamic>>((String line) {
+      line = line.substring(1, line.length - 1);
+      return json.decode(line) as Map<String, dynamic>;
+    });
+
+void _stdoutCommandResponse(Map<String, dynamic> command) {
+  stdout.writeln('[${json.encode(command)}]');
+}
+
+/// A mode for running WebDev from command-line tools.
+///
+/// Communication happens over STDIO using JSON-RPC.
+///
+/// This supports a subset of:
+/// https://github.com/flutter/flutter/blob/master/packages/flutter_tools/doc/daemon.md
+class DaemonCommand extends Command<int> {
+  @override
+  final name = 'daemon';
+
+  @override
+  final hidden = true;
+
+  @override
+  String get description =>
+      'A mode for running WebDev from command-line tools.';
+
+  @override
+  Future<int> run() async {
+    var daemon = Daemon(_stdinCommandStream, _stdoutCommandResponse);
+    await daemon.onExit;
+    return 0;
+  }
+}
diff --git a/webdev/lib/src/daemon/daemon.dart b/webdev/lib/src/daemon/daemon.dart
new file mode 100644
index 000000000..6bf05b86a
--- /dev/null
+++ b/webdev/lib/src/daemon/daemon.dart
@@ -0,0 +1,93 @@
+// Copyright (c) 2019, the Dart project authors.  Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+import 'dart:async';
+import 'dart:io';
+
+import 'daemon_domain.dart';
+import 'domain.dart';
+import 'utilites.dart';
+
+/// A collection of domains.
+///
+/// Listens for commands, routes them to the corresponding domain and provides
+/// the result.
+class Daemon {
+  Daemon(Stream<Map<String, dynamic>> commandStream, this._sendCommand) {
+    _registerDomain(DaemonDomain(this));
+
+    // TODO(grouma) - complete these other domains.
+    //_registerDomain(appDomain = AppDomain(this));
+    //_registerDomain(deviceDomain = DeviceDomain(this));
+    //_registerDomain(emulatorDomain = EmulatorDomain(this));
+
+    _commandSubscription = commandStream.listen(
+      _handleRequest,
+      onDone: () {
+        if (!_onExitCompleter.isCompleted) _onExitCompleter.complete(0);
+      },
+    );
+  }
+
+  StreamSubscription<Map<String, dynamic>> _commandSubscription;
+
+  final void Function(Map<String, dynamic>) _sendCommand;
+
+  final Completer<int> _onExitCompleter = Completer<int>();
+  final Map<String, Domain> _domainMap = <String, Domain>{};
+
+  void _registerDomain(Domain domain) {
+    _domainMap[domain.name] = domain;
+  }
+
+  Future<int> get onExit => _onExitCompleter.future;
+
+  void _handleRequest(Map<String, dynamic> request) {
+    // {id, method, params}
+
+    // [id] is an opaque type to us.
+    var id = request['id'];
+
+    if (id == null) {
+      stderr.writeln('no id for request: $request');
+      return;
+    }
+
+    try {
+      var method = request['method'] as String ?? '';
+      if (!method.contains('.')) {
+        throw ArgumentError('method not understood: $method');
+      }
+
+      var domain = method.substring(0, method.indexOf('.'));
+      var name = method.substring(method.indexOf('.') + 1);
+      if (_domainMap[domain] == null) {
+        throw ArgumentError('no domain for method: $method');
+      }
+
+      _domainMap[domain].handleCommand(
+          name, id, request['params'] as Map<String, dynamic> ?? {});
+    } catch (error, trace) {
+      send(<String, dynamic>{
+        'id': id,
+        'error': toJsonable(error),
+        'trace': '$trace',
+      });
+    }
+  }
+
+  void send(Map<String, dynamic> map) => _sendCommand(map);
+
+  void shutdown({dynamic error}) {
+    _commandSubscription?.cancel();
+    for (var domain in _domainMap.values) domain.dispose();
+    if (!_onExitCompleter.isCompleted) {
+      if (error == null) {
+        _onExitCompleter.complete(0);
+      } else {
+        _onExitCompleter.completeError(error);
+      }
+    }
+  }
+}
diff --git a/webdev/lib/src/daemon/daemon_domain.dart b/webdev/lib/src/daemon/daemon_domain.dart
new file mode 100644
index 000000000..df1bd8675
--- /dev/null
+++ b/webdev/lib/src/daemon/daemon_domain.dart
@@ -0,0 +1,37 @@
+// Copyright (c) 2019, the Dart project authors.  Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+import 'dart:async';
+import 'dart:io';
+
+import 'daemon.dart';
+import 'domain.dart';
+
+const String protocolVersion = '0.4.2';
+
+/// A collection of method and events relevant to the daemon command.
+class DaemonDomain extends Domain {
+  DaemonDomain(Daemon daemon) : super(daemon, 'daemon') {
+    registerHandler('version', _version);
+    registerHandler('shutdown', _shutdown);
+
+    sendEvent(
+      'daemon.connected',
+      {
+        'version': protocolVersion,
+        'pid': pid,
+      },
+    );
+  }
+
+  Future<String> _version(Map<String, dynamic> args) {
+    return Future<String>.value(protocolVersion);
+  }
+
+  Future<void> _shutdown(Map<String, dynamic> args) {
+    // Schedule shutdown after we return the result.
+    Timer.run(daemon.shutdown);
+    return Future<void>.value();
+  }
+}
diff --git a/webdev/lib/src/daemon/domain.dart b/webdev/lib/src/daemon/domain.dart
new file mode 100644
index 000000000..6e7ec0765
--- /dev/null
+++ b/webdev/lib/src/daemon/domain.dart
@@ -0,0 +1,55 @@
+// Copyright (c) 2019, the Dart project authors.  Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+import 'dart:async';
+
+import 'daemon.dart';
+import 'utilites.dart';
+
+/// Hosts a set of commands and events to be used with the Daemon.
+abstract class Domain {
+  Domain(this.daemon, this.name);
+
+  final Daemon daemon;
+  final String name;
+  final Map<String, CommandHandler> _handlers = <String, CommandHandler>{};
+
+  void registerHandler(String name, CommandHandler handler) {
+    _handlers[name] = handler;
+  }
+
+  @override
+  String toString() => name;
+
+  void handleCommand(String command, dynamic id, Map<String, dynamic> args) {
+    Future<dynamic>.sync(() {
+      if (_handlers.containsKey(command)) return _handlers[command](args);
+      throw ArgumentError('command not understood: $name.$command');
+    }).then<dynamic>((dynamic result) {
+      if (result == null) {
+        _send(<String, dynamic>{'id': id});
+      } else {
+        _send(<String, dynamic>{'id': id, 'result': toJsonable(result)});
+      }
+    }).catchError((dynamic error, dynamic trace) {
+      _send(<String, dynamic>{
+        'id': id,
+        'error': toJsonable(error),
+        'trace': '$trace',
+      });
+    });
+  }
+
+  void sendEvent(String name, [dynamic args]) {
+    var map = <String, dynamic>{'event': name};
+    if (args != null) map['params'] = toJsonable(args);
+    _send(map);
+  }
+
+  void _send(Map<String, dynamic> map) => daemon.send(map);
+
+  void dispose() {}
+}
+
+typedef CommandHandler = Future<dynamic> Function(Map<String, dynamic> args);
diff --git a/webdev/lib/src/daemon/utilites.dart b/webdev/lib/src/daemon/utilites.dart
new file mode 100644
index 000000000..b13b4591d
--- /dev/null
+++ b/webdev/lib/src/daemon/utilites.dart
@@ -0,0 +1,42 @@
+// Copyright (c) 2019, the Dart project authors.  Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+dynamic toJsonable(dynamic obj) {
+  if (obj is String ||
+      obj is int ||
+      obj is bool ||
+      obj is Map<dynamic, dynamic> ||
+      obj is List<dynamic> ||
+      obj == null) return obj;
+  return '$obj';
+}
+
+String getStringArg(Map<String, dynamic> args, String name,
+    {bool required = false}) {
+  if (required && !args.containsKey(name))
+    throw ArgumentError('$name is required');
+  var val = args[name];
+  if (val != null && val is! String) {
+    throw ArgumentError('$name is not a String');
+  }
+  return val as String;
+}
+
+bool getBoolArg(Map<String, dynamic> args, String name,
+    {bool required = false}) {
+  if (required && !args.containsKey(name)) {
+    throw ArgumentError('$name is required');
+  }
+  var val = args[name];
+  if (val != null && val is! bool) throw ArgumentError('$name is not a bool');
+  return val as bool;
+}
+
+int getIntArg(Map<String, dynamic> args, String name, {bool required = false}) {
+  if (required && !args.containsKey(name))
+    throw ArgumentError('$name is required');
+  var val = args[name];
+  if (val != null && val is! int) throw ArgumentError('$name is not an int');
+  return val as int;
+}
diff --git a/webdev/lib/src/webdev_command_runner.dart b/webdev/lib/src/webdev_command_runner.dart
index 3ba157cad..4e36951e0 100644
--- a/webdev/lib/src/webdev_command_runner.dart
+++ b/webdev/lib/src/webdev_command_runner.dart
@@ -8,6 +8,7 @@ import 'package:args/args.dart';
 import 'package:args/command_runner.dart';
 
 import 'command/build_command.dart';
+import 'command/daemon_command.dart';
 import 'command/serve_command.dart';
 import 'util.dart';
 import 'version.dart';
@@ -23,6 +24,7 @@ class _CommandRunner extends CommandRunner<int> {
         negatable: false, help: 'Prints the version of webdev.');
     addCommand(BuildCommand());
     addCommand(ServeCommand());
+    addCommand(DaemonCommand());
   }
 
   @override
diff --git a/webdev/test/daemon/daemon_domain_test.dart b/webdev/test/daemon/daemon_domain_test.dart
new file mode 100644
index 000000000..9cc35c26b
--- /dev/null
+++ b/webdev/test/daemon/daemon_domain_test.dart
@@ -0,0 +1,54 @@
+// Copyright (c) 2019, the Dart project authors.  Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+import 'dart:convert';
+
+import 'package:path/path.dart' as p;
+import 'package:test/test.dart';
+import 'package:test_process/test_process.dart';
+import 'package:webdev/src/util.dart';
+
+import '../test_utils.dart';
+
+void main() {
+  String exampleDirectory;
+
+  setUpAll(() async {
+    exampleDirectory = p.absolute(p.join(p.current, '..', 'example'));
+
+    var process = await TestProcess.start(pubPath, ['upgrade'],
+        workingDirectory: exampleDirectory, environment: getPubEnvironment());
+
+    await process.shouldExit(0);
+  });
+
+  group('Daemon', () {
+    group('Events', () {
+      test('.connected', () async {
+        var webdev =
+            await runWebDev(['daemon'], workingDirectory: exampleDirectory);
+        await expectLater(
+            webdev.stdout, emits(startsWith('[{"event":"daemon.connected"')));
+        await webdev.kill();
+      });
+    });
+
+    test('.version', () async {
+      var webdev =
+          await runWebDev(['daemon'], workingDirectory: exampleDirectory);
+      webdev.stdin.add(utf8.encode('[{"method":"daemon.version","id":0}]\n'));
+      await expectLater(
+          webdev.stdout, emitsThrough(equals('[{"id":0,"result":"0.4.2"}]')));
+      await webdev.kill();
+    });
+
+    test('.shutdown', () async {
+      var webdev =
+          await runWebDev(['daemon'], workingDirectory: exampleDirectory);
+      webdev.stdin.add(utf8.encode('[{"method":"daemon.shutdown","id":0}]\n'));
+      await expectLater(webdev.stdout, emitsThrough(equals('[{"id":0}]')));
+      expect(await webdev.exitCode, equals(0));
+    });
+  });
+}