Development of Windows 98 began in the 1990s, initially using the codename "Memphis" to refer to the product. Many builds were released or leaked, starting with build 1351 on December 15, 1996 and ending with Windows 98 Second Edition.
| Build Number | Date | Description | Released as |
|---|---|---|---|
| 669 | 1995 | First build of codename "Memphis" | |
| 1132 | June 16, 1996 | Very early beta on Windows 98, basically Windows 95 with small differences | Windows Memphis Pre-Alpha |
| 1387 | February 7, 1997 | First beta | Windows Memphis Beta |
| 1602 | October 3, 1997 | First build to be able to upgrade from Windows 3.1x | Windows 98 Beta |
| 1691 | February 16, 1998 | Expired on December 31, 1998 | Windows 98 Release Candidate |
| 1998 | May 11, 1998[1] | Final version | Windows 98 |
| 2222 | April 23, 1999[1] | Windows 98 Second Edition |