Dart makes creating complex applications easy, but large code size can negatively affect startup time. Dart 1.6 added support for deferred loading, which allows developers to load libraries only when needed, allowing for quicker load times and a better user experience. The Dart site has an article describing how to use deferred loading in your application. Dart 1.6 also contains a number improvements which improve the security of server applications. The Uri class is now more strict about malformed data and HttpServer now defaults to sending best-practices headers to help protect your application and your users. For summary these and others changes see the release notes . You can download Dart 1.6 from the Download Dart page . If you are running the Dart Editor, you can update by checking "About Dart Editor". Check out the Dart support page for information on getting help, filing issues, contributing to the project.