Windows Neptune
| Version of the Windows NT operating system | |
Neptune build 5111's desktop | |
| Developer | Microsoft |
|---|---|
| Working state | Historic, never released |
| Latest preview | 5.00.5111 (kernel reports) 5.50.5111 (version in many files) / December 27, 1999 |
| Marketing target | Consumer |
| Kernel type | Windows NT |
| License | Non-disclosure agreement |
| Support status | |
| Cancelled | |
Neptune was the codename for a version of Microsoft Windows under development in 1999. Based on Windows 2000, it was originally to replace the Windows 9x series and was scheduled to be the first home consumer-oriented version of Windows built on Windows NT code. Internally, the project's name was capitalized as NepTune.