[incompatible]

I think in those days all the well-known graphical browsers (Mosaic, Netscape) were proprietary, although free for personal use.

I think I used a browser in Emacs for quite a while. There was also the Chimera browser mentioned elsewhere.

[jonathankoren]

I believe NCSA Mosaic was BSD.

Andreesen was hated at UIUC in the mid 90s for essentially taking the NCSA work and and then getting rich off of it. Then to add insult to injury he called his company Mosaic Communications. The university went after him for the trademark infringement (or whatever), but I don’t think there was anything legally wrong with him taking the code. Not only was Netscape, not the only company spun off of the Mosaic work, but pretty much every browser had some NCSA code in it for years and years.

[atotic]

Andreessen was loved by the entire core Mosaic technical team. Management did not like him, because he was a leader they could not control: opinionated, outspoken. The core Mosaic tech team all left Mosaic project on the same day to join Marc at Netscape, and pursue the pure vision of what browser should be. Mosaic project never recovered. Source: I was Mr. MacMosaic.

[incompatible]

I don't remember that, and can't find a source for it. The source code was released, but I don't think it ever had a license that allowed commercial use, and was it licensed commercially to many others.

Edit: including to Spyglass, for their browser, which was later licensed by Microsoft for Explorer.

[nostrademons]

I think Netscape was a clean rewrite of the source code of NCSA Mosaic, but with the benefit of past experience and being able to look at the code. Not illegal, but still somewhat dodgy, and understandable that people who worked on the NCSA version might get mad. I remember hearing that Andreesen was none too popular at UIUC after founding Netscape, and the lawsuit over the trademark; there's a source for that here:

https://www.jwz.org/doc/about-jwz.html

[gyc]

I once took a programming class from a later (post-Andreessen)NCSA Mosaic team who would joke about Netscape coincidentally having the same bugs as NCSA Mosaic.

[dredmorbius]

How much of that was univerity politics? So vicious because the stakes are so small ...