The NIEM Message Exchange Package (MEP) Builder is an open-source tool that was built with the NIEM message package lifecycle in mind. The tool is designed to guide users through the six stages of the lifecycle and provides the necessary artifacts to support a message exchange specification, formerly known as IEPD.  It is web-based but there also options to install and build or extend the tool locally.  

It is available for download at GitHub. Users will find a readme file as well as 2 different installers, for maximum flexibility, as well as a user guide and an admin manual.  The 2 installation options are as follows: 

• Offline Installer (Recommended) – Recommended for most users and/or for air gapped / non-internet connected devices 
• Build Installer - For developers who want to rebuild the application

Additional information can be found in the readme file.  Instructions for all installations can be found in the user guide.  The user guide also has instructions on how to use the tool. The admin manual covers server deployment procedures as well as managing user privileges for organizations.