Are you fascinated by what happens beneath your code — how a compiler turns bytecode into blistering machine instructions, how a garbage collector reclaims memory without anyone noticing, how a runtime squeezes the last drop of performance out of the hardware? Maybe you've worked on garbage collection in a managed runtime like HotSpot, the .NET CLR, V8, or Chakra. Maybe you earned your expertise the hard way — tuning live services for performance and resilience under real production load. Whatever your path, the Java Runtimes Team at Amazon, owners of Amazon Corretto, would love to talk with you. Java powers the majority of services at Amazon and nearly all public-facing AWS services. When we make the runtime faster or leaner, thousands of services — and millions of customers — feel it. You will work at the intersection of compilers, garbage collection, and systems software: finding bottlenecks in real running services, developing patches to the OpenJDK compiler, runtime, and libraries, and shipping them to every Amazon developer. You'll share what you learn with the broader engineering community and contribute your improvements back to OpenJDK — where the whole world runs them too. This is deep, high-leverage systems work with an unusually direct line from your keyboard to global impact. We care about scalability, availability, and efficiency — and about going above and beyond to deliver the best possible Java experience for Amazon's internal teams, Corretto users, and the OpenJDK community. Key job responsibilities Identify areas for improvement using data from real running services, and turn those findings into concrete compiler, GC, and runtime optimizations. Design, implement, and benchmark improvements to JIT compilation, garbage collection, and core runtime subsystems in the OpenJDK compiler, runtime, and libraries. Contribute your changes upstream to OpenJDK and to Amazon Corretto, working through code review and the community process. Tune runtime behavior for performance and efficiency across x86 and Graviton (AArch64) architectures. Build profiling, observability, and auto-tuning tooling so runtime expertise scales across the fleet. Share your findings with the engineering community and help service teams adopt runtime improvements and newer JDK versions About the team Amazon Software Builder Experience (ASBX), started in 2022, is working to make Amazon the best place to build software. Every day, hundreds of thousands of Amazon software builders rely on us for the tools they build with, and for the technology, training, and community behind them. One of our most important responsibilities is shaping the language ecosystem, both inside Amazon and across the open-source community, to improve the experience for every software builder. In 2018 the team migrated Amazon's default JDK to OpenJDK, building rigorous security and quality mechanisms around it so that security and custom patches land internally the moment they are ready. We took that expertise and launched Amazon Corretto, Amazon's no-cost, production-ready distribution of OpenJDK — bringing our enhancements to customers and the OpenJDK community at large. Today we push the runtime forward across x86 and Graviton (AArch64) fleets, and we increasingly encode deep runtime expertise into tooling so that fleet-wide performance gains scale far beyond one-to-one consultation.