I've spent the last few months building BACnet tools and the result is now available in a completely free and open source BACnet webserver.
The software can run without any installation and from a USB flash drive!
Here is a small presentation of the features:
I'm a big fan of the REPL (the toolkit), especially for debugging purposes.
(For example, there is a function named `find-bacnet-port')
And the download link, if you don't want to compile it yourself:
Hopefully you will find it useful.
I would welcome any feedback and suggestions for additional features.