Ant-based Java packages are typically built from source as follows: stdenv.mkDerivation { name = "..."; src = fetchurl { ... }; buildInputs = [ jdk ant ]; buildPhase = "ant"; } Note that jdk is an alias for the OpenJDK. JAR files that are intended to be used by other packages should be installed in $out/share/java. The OpenJDK has a stdenv setup hook that adds any JARs in the share/java directories of the build inputs to the CLASSPATH environment variable. For instance, if the package libfoo installs a JAR named foo.jar in its share/java directory, and another package declares the attribute buildInputs = [ jdk libfoo ]; then CLASSPATH will be set to /nix/store/...-libfoo/share/java/foo.jar. Private JARs should be installed in a location like $out/share/package-name. If your Java package provides a program, you need to generate a wrapper script to run it using the OpenJRE. You can use makeWrapper for this: buildInputs = [ makeWrapper ]; installPhase = '' mkdir -p $out/bin makeWrapper ${jre}/bin/java $out/bin/foo \ --add-flags "-cp $out/share/java/foo.jar org.foo.Main" ''; Note the use of jre, which is the part of the OpenJDK package that contains the Java Runtime Environment. By using ${jre}/bin/java instead of ${jdk}/bin/java, you prevent your package from depending on the JDK at runtime. It is possible to use a different Java compiler than javac from the OpenJDK. For instance, to use the Eclipse Java Compiler: buildInputs = [ jre ant ecj ]; (Note that here you don’t need the full JDK as an input, but just the JRE.) The ECJ has a stdenv setup hook that sets some environment variables to cause Ant to use ECJ, but this doesn’t work with all Ant files. Similarly, you can use the GNU Java Compiler: buildInputs = [ gcj ant ]; Here, Ant will automatically use gij (the GNU Java Runtime) instead of the OpenJRE.