List of Microsoft codenames

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 * 6 on 6
 * Windows Mobile 6.1.4

A

 * ADOS
 * OS/2 1.0


 * Advanced Windows
 * The original announced name for NT-based Windows, see Razzle


 * Alder
 * Windows CE 1.0


 * Anaconda
 * Xbox Series X/S


 * Andromeda
 * Canceled phone variant of Windows Core OS


 * Another Fucking Driver
 * Ancilliary Function Driver


 * Application Framework Extensions
 * Microsoft Foundation Class Library


 * Apollo
 * Windows Phone 8


 * Asteroid
 * Windows 2000 Service Pack 1


 * Astro
 * MS-DOS 6


 * Avalon
 * Windows Presentation Foundation

B

 * Blackcomb
 * Planned successor of Windows XP and later Longhorn/Vista; named after Whistler Blackcomb, a ski resort in British Columbia popular among Microsoft executives


 * Birch
 * Windows CE 2.0


 * Blue
 * Windows 8.1


 * Bobcat
 * Windows Small Business Server 2003

C

 * Cairo
 * Canceled successor of Windows NT 3.x that aimed to implement Bill Gates's "Information at your fingertips" vision


 * Cairo Domains
 * Active Directory


 * Cairo Messaging
 * Microsoft Exchange


 * CairOLE
 * OLE 3.0


 * Cascades
 * Canceled successor to Windows Essential Business Server 2008 based on Windows Server 2008 R2.


 * Cascadia
 * Windows Terminal; also used as the name of the Cascadia Code and Mono typefaces, designed for the Terminal


 * Cashmere
 * Word for Windows


 * Cedar
 * Windows CE 3.0


 * Centro
 * Windows Essential Business Server 2008


 * Chelan
 * Windows Embedded Compact 7


 * Cherry Hill
 * Windows 11 shell experience pack updated via the Store


 * Chicago
 * Windows 95


 * Cleveland
 * Alternative name for a canceled successor of Windows 95, more commonly known as Nashville


 * Cobalt
 * The 21H2 (second half of 2021) engineering semester of Windows as a service; the base for the original release of Windows 11


 * Colorado
 * Windows Small Business Server 2011


 * Control Program/DOS
 * CP/DOS
 * OS/2 1.0; follows IBM mainframe product naming


 * Copper
 * The late 2022 engineering milestone of Windows as a service


 * Cougar
 * VMM32


 * Cougar
 * Windows Small Business Server 2008


 * Crossbow
 * Windows Mobile 6.0


 * Cutter
 * OS/2 1.3

D

 * Darwin
 * Windows Installer


 * Daytona
 * Windows NT 3.5


 * Detroit
 * USB supplement update for Windows 95 OSR2


 * DirectX Box
 * Xbox


 * DOS 5
 * OS/2 1.0; name used primarily by Microsoft—implies that OS/2 is the successor to the multitasking MS-DOS 4 (not the widely available MS-DOS 4).


 * Durango
 * Xbox One

E

 * Edmonton
 * Xbox One S


 * eHome
 * Windows Media Center


 * Eiger
 * Windows Fundamentals for Legacy PCs


 * Elroy
 * Windows Live Mail


 * Emerald
 * Windows XP Media Center Edition 2005 Update Rollup 2

F

 * Fastbike
 * Fast boot in Windows Neptune (Profile Accelerated Boot Accelerator)


 * Freestyle
 * Windows XP Media Center Edition


 * Frosting
 * Microsoft Plus! for Windows 95


 * Fire Steel
 * Internal Windows 11 self-hosting effort


 * Firebird
 * An upcoming update for Windows 10 Team.


 * Fusion
 * WinSxS


 * Fusion
 * .NET Framework CLR Loader

G

 * Galileo
 * Windows CE 3.0


 * Game SDK
 * DirectX


 * GeorgeTown
 * Surface RT


 * GeorgeTown X
 * Surface Pro

H

 * Haiku
 * Modular Windows


 * Harmony
 * Windows XP Media Center Edition 2004


 * Hydra
 * Windows NT Server 4.0, Terminal Server Edition

I

 * Idaho
 * Unrealized successor of Windows XP


 * Immersive Launcher
 * Immersive Shell
 * Start screen


 * Impala
 * Windows NT Embedded 4.0


 * Indigo
 * Windows Communication Foundation


 * Interface Manager
 * Windows 1.0


 * Iron
 * The 21H1 (first half of 2021) engineering semester of Windows as a service; the base for Windows Server 2022

J

 * Jaguar
 * The MS-DOS subsystem in Windows 95. A standalone retail release was also planned at one point, which ultimately ended up not materializing


 * Jameson
 * Windows CE 4.1


 * Janus
 * Combined bundle of Windows 3.1 and MS-DOS 5


 * Jastro
 * Combined bundle of Windows 3.1 and MS-DOS 6; portmanteau of Janus and Astro


 * Jupiter
 * Windows CE 2.0
 * Windows Runtime

L

 * Lite
 * Windows 10X


 * Lockhart
 * Xbox Series X/S


 * Lonestar
 * Windows XP Tablet PC Edition 2005


 * Longhorn
 * Windows Vista; named after a bar situated between the Whistler and Blackcomb mountains.

M

 * Macallan
 * Windows CE 5.0


 * Magneto
 * Windows Mobile 5.0


 * Manganese
 * The 20H2 (second half of 2020) engineering semester of Windows as a service


 * Mantis
 * Windows XP Embedded


 * Mars
 * Application framework used in Activity Centers, and the Help and Support Center in Windows Me and Windows XP


 * McKendric
 * Windows CE 4.2


 * Memphis
 * Windows 98


 * Merlin
 * Pocket PC 2002


 * Millennium
 * Windows Me


 * ModernPC
 * Windows 10X


 * MoGo
 * Start screen


 * Monaco
 * Visual Studio Code; adopted as the name of the Monaco Editor, the code editor component of Visual Studio Code decoupled for use in other applications


 * Monad
 * PowerShell


 * Monarch
 * Outlook PWA

N

 * Nashville
 * Internet Explorer 4; originally referred to a canceled successor of Windows 95.


 * Neptune
 * NepTune
 * Canceled NT-based successor of the Windows 9x series; project merged with Odyssey in early 2000 to form Whistler.


 * NewShell
 * A series of updates for Windows NT 3.51 that backported the Windows 95 user interface to the NT series (formally called the Shell Technology Preview), providing early testing for Windows NT 4.0


 * Nickel
 * The 2022 engineering milestone (also referred to as 22H2) of Windows as a service; the base for the Windows 11 2022 Update)


 * NoDo
 * Windows Phone 7 March 2011 update


 * NT OS/2
 * NTOS
 * NT-based rewrite of OS/2 canceled in favor of Windows NT, see Razzle


 * NT Windows
 * Alternative name for Windows NT before that name was standardized, see Razzle

O

 * O'Hare
 * Internet Explorer 1; named after the international airport near Chicago, the codename for Windows 95.


 * Odyssey
 * Unrealized successor of Windows 2000; project merged with Neptune in early 2000 to form Whistler.


 * One Outlook
 * Outlook PWA


 * Opus
 * Word for Windows


 * OS/2 3.0
 * NT-based rewrite of OS/2 canceled in favor of Windows NT, see Razzle


 * Ozone
 * Windows Mobile 2003

P

 * Panther
 * A short-lived lightweight fork of the Windows NT kernel for use in a consumer 32-bit version of Windows
 * WIM-based Windows Setup


 * Pegasus
 * Windows CE 1.0


 * Photon
 * Windows Phone 7


 * Polaris
 * Canceled desktop variant of Windows Core OS


 * Portable OS/2
 * NT-based rewrite of OS/2, see Razzle


 * Porthole
 * Windows Libraries for OS/2


 * Portico
 * Windows Phone 8 GDR1


 * Protogon
 * ReFS

Q

 * Quatro
 * Windows Home Server


 * Quebec
 * Windows Embedded Standard 7

R

 * Rapier
 * Pocket PC 2000


 * Razzle
 * Windows NT 3.1; originally a rewrite of OS/2 based on the new NT kernel design, which was canceled with the IBM-Microsoft split in favor of Windows NT; kept as the name of the Windows NT build environment


 * Ren
 * Outlook


 * Redstone
 * Windows 10 Anniversary Update through October 2018 Update; named after an ingame resource from Minecraft.

S

 * S14
 * Spring '14
 * Windows 8.1 Update 1


 * Santorini
 * Windows 10X


 * Scarlett
 * Xbox Series X/S


 * Scorpio
 * Xbox One S


 * Shell Update Release
 * Windows NT 4.0


 * Sherlock
 * Dr. Watson


 * Sloop
 * OS/2 1.2


 * Snowball
 * Windows for Workgroups 3.11


 * Solution Server
 * Windows MultiPoint Server 2010


 * Sparta
 * Windows for Workgroups 3.1


 * Spartan
 * Microsoft Edge


 * Stimpy
 * Windows 95 shell and user interface


 * Stimpy
 * Outlook


 * Sun Valley
 * Windows 11


 * Symphony
 * Windows XP Media Center Edition 2005

T

 * Take Home
 * Windows Media Center internal dogfooding effort


 * Talisker
 * Windows CE 4.0


 * Tango
 * Windows Phone 7.5 July 2012 update


 * The Fucking Clown
 * Office Assistant


 * Titanium
 * Windows Mobile 6.5


 * Titanium
 * The 19H1 (first half of 2019) engineering semester of Windows as a service; the base for the Windows 10 May 2019 Update


 * Trimaran
 * OS/2 1.1


 * Triton
 * Planned minor update for Neptune


 * Tukwila
 * Internal effort to advocate for smaller and more easily achievable NT releases


 * Threshold
 * Windows 10; named after an in-game location from Halo: Combat Evolved.

V

 * Vanadium
 * The 19H2 (second half of 2019) engineering semester of Windows as a service; the base for the Windows 10 November 2019 Update


 * Vibranium
 * The 20H1 (first half of 2020) engineering semester of Windows as a service; the base for the Windows 10 May 2020 Update and later. Named after the fictional mineral from Marvel Comics to prevent confusion with the Chromium project


 * Vienna
 * Short-lived name for Blackcomb after a 2006 rename; the name was supposed to start a new set of codenames derived from popular cities and locations known for their "vistas".


 * Vail
 * Windows Home Server 2011

W

 * Whistler
 * Windows XP, Windows Server 2003; named after Whistler Blackcomb, a ski resort in British Columbia popular among Microsoft executives


 * Winball
 * Windows for Workgroups 3.1


 * Window Manager
 * Windows 1.0


 * Windows 7
 * Windows 7; coined by incrementing the version number of Windows Vista (6.0) by one


 * Windows 8
 * Windows 8


 * Windows NT 3.99
 * Internal effort to advocate for smaller and more easily achievable NT releases


 * Windows NT 5.0
 * Windows 2000; not a codename per se—according to a member of the development team, "Jim Allchin didn't like codenames."


 * Windows Presentation Foundation/Everywhere
 * Silverlight


 * WMS 2
 * Windows MultiPoint Server 2011


 * WMS 3
 * Windows MultiPoint Server 2012


 * Wren
 * Outlook; originated from Bill Gates mistaking Ren, the proper codename, for Christopher Wren, the architect of St. Paul's Cathedral.

X

 * Xenon
 * Xbox 360

Y

 * Yamazaki
 * Windows CE 6.0

Z

 * Zinc
 * The early 2023 engineering milestone of Windows as a service