This BACnet library provides a BACnet application layer, network layer and media access (MAC) layer communications services for an embedded system.
http://bacpypes.sourceforge.net
This BACnet library provides a BACnet application layer and network layer written in Python for daemons, scripting, and graphical interfaces.
The BACnet Firewall Router (BTR) is an application that combines BACnet routing capability with traffic management functions to carefully control access to building automation and control networks.
https://github.com/infiniteautomation/BACnet4J
A high-performance implementation of the BACnet I/P and MS/TP protocol written for Java (minimum version 1.5) by Serotonin Software. Supports all BACnet services and full message segregation. Can be used for field devices or for control platforms.
Virtually no documentation.
https://github.com/Frozenlock/bacure
A clojure library wrapping the BACnet4J. Built to provide a seamless Clojure experience.
Documentation : http://frozenlock.github.io/bacure/index.html
http://sourceforge.net/projects/vts/
Visual Test Shell (VTS) is an application for testing the BACnet functionality of devices used in building automation systems.
http://sourceforge.net/projects/yetanotherbacnetexplorer/
Small graphical explorer program written in c#, for browsing BACnet devices. Currently supports both BACnet IP + BACnet MSTP + BACnet PTP.