No, Firebase is not an open-source platform. It is a comprehensive mobile and web development platform that is owned and operated by Google.

Firebase provides a variety of tools and services for building, managing, and scaling mobile and web apps, including a cloud-hosted NoSQL database, a serverless platform for running code, a static and dynamic web hosting platform, and various backend services for authentication, analytics, and crash reporting.

While Firebase is not open-source, some of the underlying technologies that it uses are open-source. For example, the Firebase Realtime Database and Cloud Firestore are built on top of the open-source LevelDB and BigTable technologies, respectively.

Additionally, Google has released a number of open-source libraries and tools that are related to Firebase, including the Firebase SDKs for Android, iOS, and web development, and the Firebase CLI for managing Firebase projects from the command line. These tools are available for developers to use and contribute to under open-source licenses.