After I recently reinstalled my MacBook Air with Mac OS X Mavericks, I encountered for the first time Gatekeeper – the sandbox, that won’t allow to run applications from unverified sources to improve Mac OS X security. However that also excludes the commonly used IDE Eclipse.

Problem: Eclipse (or other application) won’t launch in Mac OS X Mavericks.

Solution: delete extended quarantine attribute – which probably Safari or Finder added after the download. Enter the following command in the Terminal to allow Eclipse to launch.

$ xattr -d com.apple.quarantine eclipse.app

This way you can leave the sandbox in place and only add exceptions for applications, that you cannot live without. For further information on and graphical configuration options of Gatekeeper check out this Ars Technica article.