How to Build an Executable from a JAR using ExecJAR - Mostly nerdless

execjar is a new CLI tool and Maven plugin that creates executable files from Java JAR files by prepending a shell launcher script to the JAR. Since JARs are ZIP files with their central directory at the end, a shell script can be prepended without corrupting the archive. The tool auto-generates a launcher script that finds a suitable JVM, honors version constraints, and sets environment variables. Benchmarks comparing execjar against GraalVM native-image show execjar builds ~100x faster and produces smaller binaries (4.8MB vs 31MB), while native-image executables run about 2x faster at startup. For long-running commands, the difference is negligible. The tool is UNIX-only and requires a fat JAR with all dependencies bundled.