Amazon uses Amazon Q Developer to upgrade its internal Java applications

The problem

Updating foundational software is tedious but important work. Developers tend to put it off because it adds no visible features. Amazon had a very large base of applications written in Java (a common programming language) that needed to move to newer versions of it, with security and infrastructure cost benefits waiting on the other side.

What they built

Amazon used the code transformation capability of Amazon Q Developer on its own internal systems. The tool takes an application on an older Java version and produces the changes needed to run it on Java 17. Developers then review the output.

How they did it

Per CEO Andy Jassy's post, Amazon integrated Amazon Q into its internal systems to update its foundational Java software. Developers reviewed the generated changes, and Jassy reported that 79% of the auto-generated code reviews shipped with no further edits. The sources do not describe the review process, testing setup or team structure in more detail.

Results

Jassy said the average time to upgrade an application to Java 17 dropped from about 50 developer-days to a few hours. He said Amazon estimates this saved the equivalent of 4,500 developer-years and that more than half of its production Java systems were upgraded in under six months. He also cited an estimated $260M in annualized efficiency gains from better security and lower infrastructure costs. These are Amazon's own estimates.

What to copy

Start with a bounded, well-understood migration where success is easy to check (the application still builds and passes tests). Track how often reviewers accept the generated change as is.