EclEmma is described as 'free Java code coverage tool for Eclipse, available under the Eclipse Public License. It brings code coverage analysis directly into the Eclipse workbench'. There are five alternatives to EclEmma for a variety of platforms, including Mac, Windows, Linux, Eclipse and IntelliJ IDEA. The best alternative is CodeCover, which is both free and Open Source. Other great apps like EclEmma are cobertura (Free, Open Source), Atlassian Clover (Free, Open Source), OpenClover (Free, Open Source) and Coverlipse (Free, Open Source).
CodeCover is a free glass-box testing tool developed in 2007 at the University of Stuttgart. CodeCover measures statement, branch, loop, term coverage (subsumes MC/DC), question mark operator coverage, and synchronized coverage.
OpenClover is a free and open-source code coverage tool for Java, Groovy and AspectJ. It's based on the open-sourced version of Atlassian Clover®, the world's most sophisticated code coverage tool. Attack your top project risks first.
SourceForge presents the Coverlipse project. Coverlipse is an open source application. SourceForge provides the world's largest selection of Open Source Software. An eclipse plugin for code coverage visualization of JUnit Tests. Especially useful for test-first development.