BSD or BSD-style license: http://www.opensource.org/licenses/bsd-license.php
The BSD license is fairly permissive, placing few restrictions on the developer or user. As a developer, you may distribute source or binaries (with or without source code). As a tool user, you may modify and redistribute this tool or resource. If source code is distributed, a user may browse the source code to understand the tool's workings, modify the tool to better suit local needs, and share a modified version. If source code is not distributed, a user may still redistribute the tool as part of another package.