Run Web Start based applications after the release of Java 11

OpenWebStart: A Java Web Start Alternative for Modern Java Versions

Even years after the end of Java Web Start, many organizations still face the same challenge: applications based on JNLP need to keep running reliably — despite modern Java versions no longer supporting this technology.

In established system landscapes, this is not a niche issue. Many of these applications continue to play a critical role in daily operations. Rewriting them from scratch is often costly, risky, or simply not feasible in the short term.

OpenWebStart provides a pragmatic solution: an open-source reimplementation that allows existing Java Web Start applications to run on current Java versions.

What is OpenWebStart?

OpenWebStart is an open-source implementation for running Java applications via JNLP (Java Network Launch Protocol). It is based on IcedTea-Web and enables existing applications to be launched using familiar mechanisms.

Unlike the original Oracle implementation, OpenWebStart is designed for modern Java environments and is actively maintained. This makes it a viable option for organizations that need to continue operating existing deployments without major changes.

Typical Use Cases

In practice, OpenWebStart is primarily about keeping existing systems operational.

Common scenarios include:

  • Running legacy business applications
    Applications that have evolved over many years and are deeply embedded in business processes need to remain stable and available.

  • Migration to newer Java versions
    Moving from Java 8 to Java 11 or later removes Java Web Start. OpenWebStart fills this gap.

  • Centralized application distribution
    Applications can still be launched via a link, without traditional installation or manual updates on client machines.

  • Operating in controlled or regulated environments
    Stability, traceability, and controlled updates often take precedence over rapid technological change.

Common Questions

What is an alternative to Java Web Start?

OpenWebStart is one of the most widely used open-source alternatives for running JNLP-based applications on modern Java versions.

Why won’t my JNLP file start anymore?

Since Java 11, Java Web Start is no longer part of the JDK. As a result, JNLP files cannot be executed directly without additional tools like OpenWebStart.

OpenWebStart is installed, but the application won’t start — why?

In most cases, the issue is not the tool itself but the surrounding setup. Common causes include:

  • missing or invalid code signing
  • restrictive security settings
  • network or proxy configurations
  • inconsistencies between Java versions

Reviewing logs and JNLP configuration usually provides quick insights into the root cause. If issues persist, the OpenWebStart community support board is a good place to search for similar cases or ask questions. For organizations requiring guaranteed SLAs, commercial support options are also available.

Our Perspective at Karakun

We have been working with Java client technologies for many years, are key contributors to OpenWebStart, and actively maintain the project.

In real-world projects, the challenge is rarely purely technical. Instead, it often involves broader questions:

  • How long should an existing application remain in operation?
  • What changes are required to keep it compatible with modern platforms?
  • When does it make sense to migrate — and when does it not?

OpenWebStart is often a practical building block in these situations. It allows teams to stabilize existing systems and make informed decisions, instead of rushing into costly rewrites.

Further Information

For detailed information on installation, configuration, and downloads, visit the official OpenWebStart website. The source code and project documentation are available on GitHub.