Dentsusoken is a Japanese systems-integration house whose open-source group maintains Kopi, a lightweight JDK version manager built for Windows, macOS and Linux. Engineers working on polyglot micro-services, CI pipelines or Android builds use Kopi to install, swap and remove Oracle, OpenJDK, GraalVM, Liberica, Corretto and Zulu distributions without touching environment variables or registry keys. A single kopi add command fetches the requested JDK from upstream vendors, unpacks it into a user-local repository and wires the JAVA_HOME and PATH changes automatically; kopi list shows every installed runtime with vendor, feature release and CPU patch level, while kopi use activates the chosen JVM in the current shell or globally. Because Kopi stores each JDK in isolated folders and leaves the system directory untouched, developers can regression-test legacy applications on Java 8, run Spring Boot modules on Java 17 and evaluate Loom builds on Java 21 in parallel terminals. The tool also exports scripted environment snapshots that DevOps teams replay inside Docker stages or GitHub Actions runners, eliminating “works on my machine” drift. Kopi is released under the MIT licence and is available for free on get.nero.com, where downloads are delivered through trusted Windows package sources such as winget, always install the latest upstream build, and can be queued for batch installation alongside other utilities.