Facebook Open Sources Sonar

Here comes a good news from Facebook for developers after a very long time. Facebook has recently launched the Sonar, an extensible cross-platform debugging tool, for engineers to develop new features, optimize performance, and investigate bugs while working on apps.
The Sonar tool will provide a surface where framework experts and developers can convey latest and important information to framework users.
Further, the Sonar tool is now can be used as open source project to help in accelerating the app development process. The tool helps in improving current tools through more visual and interactive experience which is extensible and fits in specific needs of engineers.
Source: Facebook
Now, Sonar is recommended over Stetho, an Android debugging bridge built on Chrome's developer tools, for specific features. You can find the release of Sonar on GitHub
Silent Features Of Sonar:
Extensions in Sonar
The tool will enable Facebook engineers with access to a view hierarchy that resembles with Litho and ComponentKit components as well as stream the GraphQL requests.
An open source architecture
The tool can interact with the desktop client as it is made up of the desktop client and a mobile SDK which can be installed in Android or iOS application.
Source: Facebook
A tool for the open source community
The tool also works for engineers working on mobile applications. These plugins can also be integrated into existing apps using Sonar's SDK with just a few lines of code.
To learn more you can go through the official blog.