Pants itself adds items to the ivy classpath, see: - https://github.com/pantsbuild/pants/blob/master/pants.ini#L85-L87 - https://github.com/pantsbuild/pants/blob/master/build-support/ivy/ivy.xml This is only documented roundabout in http://www.pantsbuild.org/tshoot.html under the 'Ivy HTTP Debugging' heading.