The Firebase JavaScript SDK implements the client-side libraries used by applications using Firebase services. This SDK is distributed via:

• CDN
• npm package

To get started using Firebase, see Add Firebase to your JavaScript Project.

Version 9 has a redesigned API that supports tree-shaking. Read the Upgrade Guide to learn more.

Please see Environment Support.

Before you can start working on the Firebase JS SDK, you need to have Node.js installed on your machine. As of August 17, 2026 the team has been testing with Node.js version 24.19.0, but the required version of Node.js may change as we update our dependencies.

To download Node.js visit https://nodejs.org/en/download/.

NOTE: You can use a tool like NVM or N to install and manage multiple node versions

In addition to Node.js we use yarn to facilitate multi package development.

To install yarn follow the instructions listed on their website: https://yarnpkg.com/en/docs/install

This repo currently supports building with yarn 1.x. For instance, after installing yarn, run

$ yarn set version 1.22.22

The closure compiler requires a modern Java installation. Java 11+ should be installed: https://www.oracle.com/java/technologies/downloads/#java11

You can verify your setup by running the following commands in your terminal:

$ node -v
$ yarn -v
$ java -version

Your node version should be 20.19.0 or greater, your yarn version should be ^1.22.22 (Yarn 1.x), and your java version should be 11.0 or greater.

NOTE: We will update the documentation as new versions are required, however for continuing development on the SDK, staying up to date on the stable versions of these packages is advised

Once you have Node.js and yarn installed on your machine and have validated that you are running the proper version, you can set up the development environment by running the following at the root of the SDK: