If you’ve tried out Flutter , you’ve already used strong mode checks from the Dart analyzer.Given the benefits of strong mode, and the large number of users already using it, we have decided to make strong mode the standard type system for Dart. This means that we will initiate a move to 2.0 in three phases: 1) strong mode is opt in, 2) strong mode is the default, and 3) strong mode is the only mode. We are making sure that Dart users have a smooth transition to the new type system, as explained in more detail below.Moving to strong mode also enables the use of the new Dart development compiler ( dartdevc , also known as DDC) instead of Dartium for web app development. With dartdevc you get faster developer cycles and can use any recent version of Chrome – unlocking among other things the use of bleeding edge browser features. Once the developer experience with dartdevc matches that of Dartium, we’ll stop maintaining Dartium.You should continue to use dart2js to compile your final app. Where dartdevc is optimized for fast refreshes and easy debugging, dart2js is optimized for small generated code size and fast runtime of web apps.As mentioned above, to help prepare for the transition to strong mode, we’re moving to 2.0 in three phases: In the current phase (phase 1) you can opt in to strong mode and dartdevc. Phase 2 will make strong mode the default, but you'll be able to opt out. Finally, phase 3 will make strong mode the only type system for Dart, and eventually we’ll remove Dartium.We believe these changes will help you and your team be more productive when writing Dart apps. If you’d like to try out strong mode and dartdevc with your web apps, check out the Dart 1.24 announcement and follow the instructions in the Tool Changes section of the changelog. To use strong mode when building for mobile, check out flutter.io As always, we’d love to hear about your experiences with Dart and strong mode – especially if you encounter issues when transitioning to dartdevc and our new type system.