Windows codenames

Windows 3.1x/9x

Codename	Preliminary name	Final name	Notes
Janus		Windows 3.1, Windows 3.11	Same codename as Windows NT 5.0/2000 64-bit.
Kato (Winball), Sparta (Jastro)		Windows for Workgroups 3.1
Snowball (LB)		Windows for Workgroups 3.11
Chicago		Windows 95
O'Hare		Internet Explorer, first shipped in Microsoft Plus! for Windows 95	O'Hare is the main airport for the city of Chicago.
Frosting		Microsoft Plus! for Windows 95
Detroit		Windows 95 Service Pack 2
Nashville		Internet Explorer 4	Cancelled Windows version
Memphis		Windows 98	The codename was the key to activating an easter egg in Windows 98: open the "Date and Time" control panel; go to the "Timezone" page; hold the Control key and drag a line with the mouse cursor from Memphis, Egypt (or maybe Cairo, the codename of Windows NT 4 - the map is too small to tell) to Memphis, Tennessee. Still holding the Control key, drag another line from Memphis to Redmond, Washington; a window opens with the credits for Windows 98.
Dolly		Windows 98 Second Edition	Dolly refers to Dolly the Sheep, the first sheep to be cloned.
Millennium		Windows Me	Me stands for Millennium Edition

Windows NT family

Codename	Preliminary name	Final name	Notes
NT OS/2, OS/2 3.0, Portable OS/2, NTOS, Razzle		Windows NT 3.1
Daytona		Windows NT 3.5x
Cairo		N/A	Never released.
SUR (Shell Update Release)		Windows NT 4.0	Microsoft originally planned for NT 4.0 to be just a simple "Shell Update Release" to integrate the Windows 95 GUI with Windows 3.51's kernel.
Wolfpack		Microsoft Cluster Server
Hydra	Terminal Services, Terminal Server	Windows NT 4.0 Terminal Server	Terminal Server adds "multithreading" support to Windows (the ability to run multiple instances of the graphics subsystem), and the Lernaean Hydra is a mythological monster with multiple heads.
Impala		Windows NT 4.0 Embedded
	Windows NT 5.0	Windows 2000
Asteroid		Windows 2000 Service Pack 1
Janus		Windows NT 5.0 64-bit, Windows 2000 64-bit	Same codename as Windows 3.1
Neptune		N/A	Ideas project, merged to Whistler.
Whistler		Windows Whistler	Merge of Neptune and Odyssey. Named after Whistler, British Columbia, where design retreats were held.
Odyssey		N/A	Ideas project, merged to Whistler.
Sundown		Windows XP Professional x64 Edition
Mira		Windows XP Tablet PC Edition
Lonestar		Windows XP Tablet PC Edition 2005
Triton		N/A
Mantis		Windows XP Embedded
Creekside		Windows XP Starter
Trident		Windows XP Media Center Edition
eHome		Windows Media Center
Freestyle		Windows XP Media Center Edition 2003	Name of a terrain rating system in the Whistler-Blackcomb resort.
Harmony		Windows XP Media Center Edition 2004	Name of a ski lift and alpine bowl in Whistler, British Columbia.
Symphony		Windows XP Media Center Edition 2005	Name of an alpine bowl in Whistler, British Columbia.
Emerald		Windows XP Media Center Edition 2006	Name of a ski lift in Whistler, British Columbia.
Trainyard		Windows XP Service Pack 1	Trainyard was an engineering package of driver updates to ship simultaneously with Windows XP Service Pack 1, the most major of which was support for USB 2.0 which was also ported backwards to Windows 2000.
Springboard		Windows XP Service Pack 2	Name of a ski run on Blackcomb in Whistler, British Columbia.
Whistler Server, Windows 2002 Server, Windows .NET Server, Windows .NET Server 2003		Windows Server 2003
Bobcat		Windows Small Business Server 2003	Bobcat is a ski-run on Whistler Mountain.
Eiger		Windows Fundamentals for Legacy PCs	Software Assurance program. The Eiger is a mountain in the Bernese Oberland in Switzerland. The Eiger is part of a trio of mountains, The Eiger, The Mönch and The Jungfrau.
Mönch		Windows Mobile 6	VPN-s and advanced IP (Internet Protocol) security. The Mönch is a mountain in the Bernese Oberland in Switzerland. The Mönch is part of a trio of mountains, The Eiger, The Mönch and The Jungfrau.
Longhorn		Windows Vista	Named after the Longhorn Bar in the Whistler-Blackcomb resort; initially planned as an "interim release" between "Whistler" and "Blackcomb" (which is now "Vienna"). Reset in 2004 due to development issues.
Cougar		Windows Small Business Server 2008	Cougar is a ski-run on Whistler Mountain.
Q, Quattro		Windows Home Server	Announced at CES 2007. Original project codename was "Quattro" because it was the leader of the project's 4th attempt at building a home server at Microsoft. Renamed to Q once the project moved out of incubation stage.
Windows 7		Windows 7	"Windows 7" was the original project codename. It was decided that this must be kept.
Windows Server 7		Windows Server 2008 R2	In development. Planned "mid-size" (25-500 PC) edition of Longhorn Server.[1].
Vail, Home Server 7		Windows Home Server 2010
Windows 8		Windows 8
Server 8		Windows Server 2012
Metro		Windows 8 Style UI	Renamed from Metro because of legal issues involving the German Metro company.
Jupiter		Windows RT	Windows 8 application framework.
Blue		Windows 8.1
Server Blue, Server 8.1		Windows Server 2012 R2
8.1 Update 1		Windows 8.1 Update 1
Threshold		Windows 10
Threshold 2		Windows 10 November Update
Threshold Server		Windows Server 2016
Redstone		Windows 10 Anniversary Update	Redstone is a mineral and item in Minecraft, a game product by Mojang and Microsoft bought it in 2015
Redstone 2		Windows 10 Creators Update
Redstone 3		Windows 10 Fall Creators Update
Redstone 3 Server		Windows Server version 1709
Redstone 4	Windows 10 Spring Creators Update	Windows 10 April 2018 Update
Redstone 4 Server		Windows Server version 1803
Redstone 5		Windows 10 October 2018 Update
Redstone 5 Server		Windows Server 2019, Windows Server version 1809
19H1	Windows 10 19H1	Windows 10 May 2019 Update
Server 19H1		Windows Server version 1903
19H2, Vanadium	Windows 10 19H2	Windows 10 version 1909
Server 19H2, Server Vanadium	Windows Server 19H2	Windows Server version 1909
20H1, Vibranium	Windows 10 20H1	Windows 10 version 2004
Server 20H1, Server Vibranium	Windows Server 20H1	Windows Server version 2004
20H2, Magnanese (insider preview only)		Windows 10 20H2
Server 20H2 (insider preview only)		Windows Server 20H2
Iron		Windows 10 Iron
Server Iron		Windows Server Iron