<p>Oracle announced Project Detroit at JavaOne, an initiative to make Java interoperate directly with JavaScript and Python. Rather than reimplementing those languages on the JVM (as Project Nashorn did for JavaScript), Project Detroit embeds the V8 and CPython runtimes inside the JVM process itself.</p>
<p>The project will be proposed as an official OpenJDK project. It provides implementations of the <code>javax.script</code> API backed by Chrome V8 for JavaScript and CPython for Python.</p>
<h2>Why this approach is different</h2>
<p>Previous attempts at JVM-based polyglot support, like Nashorn, required reimplementing the target language from scratch. That meant constant catch-up work and inevitable compatibility gaps with the real ecosystems. Project Detroit sidesteps that by using the Foreign Function and Memory (FFM) API introduced in Java 22 to call into the actual V8 and CPython runtimes directly.</p>
<p>The practical benefits:</p>
<ul>
<li>Full compatibility with existing JavaScript and Python libraries, including Python AI libraries that Java developers increasingly want to access</li>
<li>Better performance, since you’re running the real runtimes rather than a JVM reimplementation</li>
<li>Heap isolation between the JVM and the embedded runtimes, which improves security</li>
</ul>
<p>The project was originally proposed in 2018 and then abandoned. It’s been revived now partly because the FFM API finally gives it a solid foundation, and partly because demand has grown — particularly around AI tooling where Python dominates.</p>
<p>Support for additional languages beyond Python and JavaScript is planned for the future.</p>
<h2>Other announcements from JavaOne</h2>
<p>Oracle also shipped Java 26, a short-term release that adds HTTP/3 support and removes the Java Applet API. The Helidon microservices framework is joining OpenJDK, and Oracle introduced the Java Verified Portfolio covering Helidon, JavaFX, and the VS Code Java extension. On the AI side, Oracle highlighted Langchain4j, Spring AI, and the Embabel agent framework as part of Java’s growing AI ecosystem.</p>


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Oracle announced Project Detroit at JavaOne, an initiative to embed V8 (JavaScript) and CPython (Python) runtimes directly inside the JVM process using the Foreign Function and Memory (FFM) API introduced in Java 22. Unlike previous approaches like Nashorn that reimplemented languages on the JVM, Project Detroit embeds the actual runtimes, enabling full compatibility with existing JS and Python ecosystems, better performance, and heap isolation for security. The project will be proposed as an official OpenJDK project and implements the javax.script API. Originally proposed in 2018 and abandoned, it was revived due to the FFM API's maturity and growing demand for Python AI library access from Java. Other JavaOne announcements include Java 26 with HTTP/3 support, Helidon joining OpenJDK, and highlights of Java's AI ecosystem including Langchain4j and Spring AI.

Project Detroit: Oracle's plan to embed Python and JavaScript runtimes inside the JVM

<p>those lawyers now want to run python with java too? Oh the unholyness of this!</p>
