I present "Bach.java" - a lightweight build tool for Java. Bach.java uses jshell/java to build modular Java projects. It supports a "zero installation" run mode, convention over configuration pragmatism, simple properties file to tweak defaults, and an API to build custom projects. In the spirit of Rémix Forax, who wrote: "No need to be a maven to be able to use a build tool", Bach.java is targeted to coders of small to mid-size Java projects, who want to focus on their ideas and modules instead of learning and taming a build tool.