Jest, Meta Open Source’s open source JavaScript testing framework, has been officially transferred to the OpenJS Foundation. Jest is the most popular testing framework in the JavaScript ecosystem, with over 17 million weekly downloads and over 38,000 GitHub stars. It is used by companies of all sizes, including Amazon, Google, Microsoft, and Stripe. As Jest evolves as an open source project, we believe that passing ownership to the community — and putting it into a foundation dedicated to promoting the JavaScript ecosystem — is an exciting and natural next step.
We’ve always viewed open source as a method to share our work and assist others in iterating and moving swiftly. This change has no impact on how Jest is created or distributed, and it has no direct impact on developers who use Jest to test their apps.
Jest (internally referred to as “jst”) is an open source JavaScript testing framework that enables developers to create high-performance tests with minimal configuration and a straightforward API. Jest’s motto is “a beautiful JavaScript Testing Framework,” and in polls such as State of JS, Jest has garnered user satisfaction scores of above 90%.
When Facebook’s chat component was redone in JavaScript in 2011, Jest was born. Due to the increased complexity, a rapid test-driven development cycle was required. It was open sourced in 2014 and maintained part-time by Meta developers until 2016, when Christoph Nakazawa, a former Meta engineer and current Jest core contributor, took over the project and revamped it with a dedicated team. Many of the features that users recognise today in Jest were established during that time by Meta engineers, including performance, watch mode, and snapshot testing.
The project’s external community of open source contributors evolved in tandem with it. Meta launched the Jest Open Collective in 2018 to help non-Meta employees create and maintain Jest.
The Jest Open Collective has raised more than $70,000 for the Jest open source community to far. Jest has had significant enhancements thanks to the open source community, including jest-each, inline snapshots, interactive snapshot mode, watch mode plugins, better defaults, ESM support, and more.
Jest is now mostly maintained by an external group of core contributors lead by Simen Bekkhus. In fact, outside of Meta, practically all of the additions to Jest since 2018 have been from open source contributors. We believe it is better for the community to take ownership of the project because it is maintained by the community. As a result, we’re handing over ownership of Jest to the Jest core team via OpenJS today.
