Note that the version history on unixdude's site is not up to date, the most recent version is 3.1, which was published by Andreas yesterday.
The current source code can be found in the "branch_softfloat" branch on sourceforge's svn: https://sourceforge.net/projects/previous/
I equally now don’t trust the source forge source either , unless you know Andreas somehow and can vouch for them. The official website linked to from sourceforge is derelict with a last update from 2016 and version 1.4.
http://previous.alternative-system.com/
In 2023 a let’s encrypt script fixes this in 10 minutes and no automation linking. And thr gap of the last update from 2016 is huge. Feels like the project doesn’t have control. I just want people to learn and have a good time and not be in harms way while doing it.
I know jgrahamc would say I’m overthinking this. But I’m hopping they will weigh in and give wisdom as they do.
unixdude knows that his webpage is outdated and is working on an update (see the "What Needs to be done for a NeXT Emulator" thread in the Emulation / Virtualization subforum).