[nickdothutton]

While TCP/IP was open source and not controlled by any 1 vendor, quite a few companies made good money from selling TCP/IP stacks and won themselves billion dollar valuations in the process[1][2]. Of course this was during a time when Microsoft saw no point in including an IP stack with their OS, or indeed much point in connecting to the Internet at all! Some of the younger readers may find these things hard to believe.

[1] https://en.wikipedia.org/wiki/FTP_Software [2] https://en.wikipedia.org/wiki/NetManage

[tomwheeler]

Don't forget Trumpet Winsock [1]. I worked for an ISP at the time that provided it on a floppy disk (along with a newsreader, FTP client, telnet client, and web browser). Although I doubt many customers paid for it, Trumpet Winsock was shareware and very widely used on Windows 3.x.

[1] https://en.wikipedia.org/wiki/Trumpet_Winsock