How Netflix Really Uses Java

Netflix is predominantly a Java shop.

Every backend application (including internal apps, streaming, and movie production apps) at Netflix is a Java application.

However, the Java stack is not static and has gone through multiple iterations over the years.

Here are the details of those iterations:

• API Gateway

  Netflix follows a microservices architecture. Every piece of functionality and data is owned by a microservice built using Java (initially version 8)

• BFFs with Groovy & RxJava

  Using a single gateway for multiple clients was a problem for Netflix because each client (such as TV, mobile apps, or web browser) had subtle differences.

  To handle this, Netflix used the Backend-for-Frontend (BFF) pattern. Zuul was moved to the role of a proxy

• GraphQL Federation

  The Groovy and RxJava approach required more work from the UI developers in creating the Groovy scripts. Also, reactive programming is generally hard.