Remember when they rewrote their app and blogged about it? I do!

https://www.joelonsoftware.com/2002/04/11/our-net-strategy/

It was a (slow) migration, though, not a rewrite from scratch. They kept shipping software.

Exactly my point. The way the vast majority of rewrites happen.

yep, that’s the right way to do it.

I shouldn’t, but all these posts read like distant history to me with Fog Creek gone.

As if source code rusted except in this case, Netscape's descendant did rust -- in a different way.