Amazon upgraded 30,000 internal apps to Java 17 with Amazon Q Developer

Amazon used its own coding agent to move tens of thousands of internal applications from Java 8 and 11 to Java 17. Andy Jassy said it saved about 4,500 developer-years of work.

Organization: Amazon
Industry: E-commerce & Cloud
When: Aug 2024
Evidence: Company reported
Agents and tools: Amazon Q Developer

Reported outcome

30,000 apps upgraded. Amazon estimates 4,500 developer-years saved and $260M a year from performance gains.

30,000
Apps upgraded
~4,500 (estimate)
Developer-years saved
$260M (estimate)
Annual savings
~50 dev-days → hours
Avg. upgrade time

Caveats

Stated by the company that uses the agent (blog, earnings call, interview). Not independently audited.

Amazon's own internal estimates. Amazon also sells the tool.
Time saved was estimated by counting migrated dependencies, at about one developer-day each.
The $260M figure comes from hosts removed thanks to Java 17 performance, not from the agent itself.

What the agent does

The agent reads a Java application, updates its build files and dependencies, changes code that breaks under Java 17, and runs the build and tests. A developer reviews the change before it ships.

Why this works

Language and framework upgrades are boring, high-volume, and easy to verify. The compiler and test suite give the agent fast, honest feedback. Most of the risk is in the long tail of unusual apps, which still need a human.

What to copy

Pick one upgrade type (for example, a major framework version) and do it across the whole fleet.
Make "build passes and tests pass" the minimum gate before a human looks.
Count the work in units you can measure (dependencies, files, apps) so the savings estimate is honest.

Starter prompt

Written by us. Works with most coding agents.

Upgrade this project from Java {old_version} to Java 17.

Steps:
1. Update the build file (Maven/Gradle) and the toolchain version.
2. Upgrade dependencies only as far as needed for Java 17 support.
3. Fix compile errors and deprecated API uses.
4. Run the full test suite. Fix failures caused by the upgrade.

Rules:
- Do not change business logic.
- If a test fails for a reason not related to the upgrade, stop and report it.
- Summarize every dependency you changed and why.