Open Source for Windows

• Audio editing tools
• Business Software
• CAD software
• Calendar Software
• CD Writing
• Compression/ZIP
• Databases
• Desktop Environments
• Dictionaries
• Drivers/Hardware
• Educational
• Emulators
• FTP clients
• Firewall & NAT
• File Systems
• Games
• GPS
• Graphics
• Instant Messaging
• Internet Voice chat
• IRC clients
• Mail & News
• Media Players (audio)
• Media Players (video)
• Media Players (codecs)
• Networking tools
• NTP clients
• Office tools
• Operating Systems
• PostScript viewers
• Programming
• Remote access
• Sciences and Math
• Security, Privacy, Protection,...
• Server software
• SCP (SecureCoPy) clients
• Stream Downloaders
• Text editors
• Utilities
• Video capture/processing
• VJ Software
• Web browsers
• Webcam
• Web editors
• Webgrabbers

Audio editing tools

• CDex [GNU GPL]
• Ogg Vorbis
• Musepack [GNU LGPL, BSD]
• Audacity [GNU GPL]
• CD-DA X-Tractor [GNU GPL]
• LAME [GNU LGPL]:
  • Official site
• AudioCoding
• Mp3splt [GNU GPL]
• Mp3Wrap [GNU GPL]
• Alba Extractor [GNU GPL]
• PeerCast [GNU GPL]
• GNUMP3d [GNU GPL]
• GramoFile [GNU GPL]
• FFmpeg [GNU LGPL]
• JAZZ++ [GNU GPL]
• Mixere [GNU GPL]
• Open Sound World [Other/Proprietary License]
• split3pm [No license]
• BonkEnc [GNU GPL]
• Hydrogen

• EasyTAG
• MusicBrainz Tagger [GNU GPL]
• Mp3 Tag Tools [GNU GPL]

Business Software

• opentaps
• vtiger CRM
• webERP
• Apache OFBiz®
• ERP5
• GNU Enterprise
• Compiere ERP and CRM
• SQL-Ledger
• osCommerce
• Quasar Accounting
• TurboCASH
• GLPI

CAD and Electronic Design

• BRL-CAD
• Open CASCADE
• Sailcut CAD

• KICAD
• XCircuit
• gEDA
• TinyCAD
• QUCS
• LTSpice

Calendar Software

• WebCalendar [GNU GPL]
• Sunbird [MPL/GPL/LGPL]

CD Writing

• Infra Recorder [GNU GPL]
• cdrtfe (cdrtools Front End) [GNU GPL]
• CDRDAO [GNU GPL]
• CDRECORD
• Cdrtools with SPTI
• SoftCDWriter
• jCDWriter [GNU GPL]

Compression/ZIP

• 7-Zip
• PeaZip
• Zzip
• Info-ZIP
• BiGZiP
• Open-source ARJ
• unar
• Ultimate Packer for eXecutables (UPX)

Databases

• Ingres Database
• MySQL [GNU GPL]
• PostgreSQL [BSD]
• DBDesigner [GNU GPL]
• Database Design Tool [GNU GPL]
• Firebird [InterBase Public License]
• FlameRobin [Other/Proprietary]
• SAP DB [GNU GPL and GNU LGPL]
• FutureSQL [GNU GPL]
• InterBase [InterBase Public License]
• OpenOfficeorg BASE [GNU GPL/LGPL and SISSL]

Desktop Environments & Shell

• BlackBox For Windows [GNU GPL]
• Blueberry 3D-Desktop [GNU GPL]
• bbLean [GNU GPL]
• CyGNOME [GNU GPL]
• CyGNOME 2 [GNU GPL]
• Geoshell [GNU GPL]
• KDE-Cygwin [GNU GPL]
• LiteStep [GNU GPL]
• SharpEnvironment [GNU LGPL]
• Virtual Dimension [GNU GPL]
• xoblite / Blackbox for Windows [GNU GPL]
• DM2 [GNU GPL]

Dictionaries

• jDictionary [LGPL]
• Podo dictionary [GPL]
• JaLingo
• Freedict:
• Hyperdictionary
• Ergane
• ITRANS
• Babiloo [GNU GPL]
• StarDict[GNU GPL]

Drivers/Hardware

• WDM bt848/bt878 video adquisition driver [LGPL]
• RadeonTweaker [GNU GPL]

Educational

• Childsplay [GNU GPL]
• Claroline [GNU GPL]
• dokeos [GNU GPL]
• GCompris [GNU GPL]

Emulators

• Amiga WinUAE
• Apple AppleWin [GNU GPL]
• Atari Stella [GNU GPL]
• DOS DOSBox [GNU GPL]
• GameCube + Wii Dolphin Emulator
• IA-32 Bochs IA-32 Emulator Project
• Nintendo Switch yuzu Ryujinx
• Sega Master System Osmose [GNU GPL]
• Sega Genesis / Mega Drive Generator [GNU GPL]
• PowerPC PearPC [GNU GPL]
• Sega GenesisCD/32X Gens [GNU GPL]
• Sega Dreamcast Swirly [GNU GPL]
• Sega Saturn Yabause [GNU GPL]
• Super Nintendo ZSNES [GNU GPL]
• Nintendo 64 Nintendo 64 [GNU GPL]
• ZX Specrum Fuse [GNU GPL]
• Other QEMU [GNU GPL/GNU LGPL/MIT/BSD]

FTP clients

• FileZilla
• ncftp
• TLSWrap
• JFtp [GNU GPL]
• FFFTP

Firewall & NAT

• Core Force
• TdiFw [GNU GPL]
• DeleGate [Other/Proprietary License]
• PktFilter [BSD License] (also has a SourceForge.net project page)
• CodeSeeker [GNU GPL]
• IP Filter Firewall [GNU GPL]
• WIPFW [BSD]
• iSafer [GNU GPL]

• Pseud IP Masquerade (PIPMasq)

File systems (drivers)

• Explore2fs [GNU GPL]
• Ext2 (Linux) File System Driver for Windows NT 4.0 [LGPL]
• Ext2fsd [GNU GPL]
• FFS File System Driver [GNU GPL]
• FSDEXT2 [GPL]
• rfstool [GNU GPL]
• YaReG [GNU GPL]

GPS

• GPSBabel
• GPX Editor
• JGPSTrackEdit
• Viking GPS data editor and analyzer
• GpsPrune
• RouteConverter

Graphics

• Pencil2D
• Synfig
• Jahshaka

• Blender
• Wings 3D
• POV-Ray
• OpenFX
• Art of Illusion
• Irrlicht Engine
• Aqsis
• K-3D

• The GIMP

• nomacs
• JPEGView
• ImageGlass
• Imgv
• Cornice (development has stopped)

• LazPaint
• MyPaint
• Tux Paint

• Inkscape
• VPaint
• Skencil
• Sodipodi
• ImageMagick [Other/Proprietary License]
• Dia [GNU GPL]
• AutoTrace [GNU GPL]
• CopyRightLeft [GNU GPL]
• restoreInpaint [GNU GPL]
• Nebula [MIT]
• hugin [GNU GPL]
• potrace [GNU GPL]
• jhead [GNU GPL]
• GLE [GNU GPL]
• ASCII Generator dotNET [GNU GPL]

Instant Messaging

• Pidgin
• SIM-IM
• Miranda IM
• Miranda NG
• aMSN
• Psi
• Exodus
• WinJab
• CenterICQ
• Coccinella
• Tkabber
• Ayttm
• BuddySpace
• BitlBee (gateway to IM networks)
• Retroshare

Internet Voice chat

• Opal
• Speak Freely [GNU GPL]
• AsteriskWin32 [GNU GPL]

• Ekiga [GNU GPL]
• Linphone
• QuteCom [GNU GPL]
• Blink
• SIP Communicator [Apache Software License]
• PhoneGaim [GNU GPL]
• SIPp [GNU GPL]

IRC clients

• XChat [GNU GPL]
• X-Chat 2 [GNU GPL]
• KVIrc [KVIrc License]
• savIRC [GNU GPL]
• BitchX
• BoxedIrc [GNU GPL]
• HydraIRC [Other/Proprietary License]
• Bersirc [Q Public License]
• Mozilla's ChatZilla [MPL, NPL]

Mail & News

• Mozilla [NPL/MPL/LGPL/GPL]
• Mozilla SeaMonkey [MPL, NPL]
• Sylpheed-Claws
• MicroPlanet Gravity [BSD]
• Eudora
• Athea
• Mahogany
• Polarbar Mailer
• Magic Mail Monitor 3 [GNU GPL]
• Phoenix Mail
• MailReactor [GNU LGPL]
• RoundAbout [GNU GPL]
• AmphetaDesk
• KookieJar (signature generator)
• POPFile
• Outclass [GNU GPL]
• mutt [GNU GPL]
• Unixmail [GNU GPL]
• XanaNews [MPL]
• Pan [GNU GPL]
• Mozilla Thunderbird
• PopTray [GNU GPL]
• Blat [Public Domain]
• slrn [GNU GPL]
• FeedReader [GNU GPL]
• RSSOwl [Common Public License]
• Evolution
• si.Mail [GNU GPL]

• Mailfilter [GNU GPL]
• Spamihilator [GNU GPL]
• SpamBayes [Python Software Foundation]

Media Players (audio)

• Delphamp [GNU GPL]
• Zinf [GNU GPL]
• LongPlayer [GNU GPL]
• CoolPlayer [GNU GPL]
• SnackAmp [GNU GPL]
• NotifyCD [GNU GPL]
• Winamp Radio Scheduler
• MP3Gain [GNU LGPL]
• MPlayer [GNU GPL]
• MPLayer Control [GNU GPL]
• Mixxx [GNU GPL]
• Songbird [GNU GPL]
• musikCube [BSD]

Media Players (video)

• VideoLAN [GNU GPL]
• Media Player Classic (see als this page).
• Media Player Classic - Home Cinema
• Xine [GNU GPL]
• MediaPortal [GNU GPL]
• MPlayer [GNU GPL]
• GPAC
• Vitessa [GNU GPL]

Media Players (codecs)

• ffdshow (DirectShow decoding filter for decompressing DIVX movies) [GNU GPL]
• ffvfw (MPEG-4 Video for Windows codec) [GNU GPL]
• AC3Filter [GNU GPL]
• XviD [GNU GPL]
  • Koepi's XviD binaries [GNU GPL]
  • Nic's XviD binaries [GNU GPL]
  • uManiac's XviD binaries [GNU GPL]
• MediaCoder [GNU GPL]
• Theora [BSD-style]
• FLAC [GNU GPL]

Networking tools

• OCS Inventory [GNU GPL]
• Packetyzer [GNU GPL]
• WinDump [BSD]
• Analyzer [BSD]
• Ethereal Network Analyzer [GNU GPL] (deprecated)
• Wireshark [GNU GPL]
• Packetizer [GNU GPL]
• Nmap [GNU GPL]
• Show Traffic [BSD]
• daSniff [no license]
• Network Game Detect [BSD]
• Port scanner [GPL]
• ngrep [Other/Proprietary License]
• Knocker [GNU GPL]
• Winip [Artistic License]
• NetBios Scan [GNU GPL]
• NetBIOS Enumerator [GNU GPL]
• OpenVPN [GNU GPL]
• DeeEnEs [GNU GPL]
• Dynksys Dynamic IP Updater [GNU GPL]
• MyDyndns [GNU GPL]
• SSL-Explorer [GNU GPL]
• Hardscan [GNU GPL]
• tcping [GNU GPL]
• mturoute [Public Domain]
• tsb [GNU GPL]
• Scapy [GNU GPL]
• OpenRSM [GNU GPL]

NTP clients

• NetTime [BSD]
• NIST Internet Time Service [Public Domain]

Office tools

• OpenOffice.org [GNU GPL/LGPL and SISSL]
• OOExtras [LGPL]
• OOo Label Templates [GPL]
• AbiWord [GNU GPL]
• PDFCreator [GNU GPL]
• qvPDF [GNU GPL]
• pdftk, the PDF Tool Kit [GNU GPL]
• pdfsam [GNU GPL]
• Xpdf [GNU GPL]
• veraPDF
• GUIPDFTK [GNU GPL]
• PDFTOHTML [GNU GPL]
• LyX [GNU GPL]
• LaTeX:
  • MikTeX
  • fpTeX
  • TeXstudio
  • TeXnicCenter
  • AucTeX
  • VIM-LaTeX
  • TeX Live
  • proTeXt
  • TeXCAD
• WinDjView [GNU GPL]
• ganttproject [GNU GPL]
• Open Workbench [MPL]
• OpenProj
• Scribus [GNU GPL]
• gnumeric [GNU GPL]
• gnome office [GNU GPL]
• PowerTalk [GNU GPL]
• MathCast [GNU GPL]
• GnuCash

Operating Systems

• FreeDOS [GNU GPL]
• FreeDOS-32 [GNU GPL]
• ReactOS [GNU GPL]
• Visopsys [GNU GPL]

PostScript viewers

• Ghostscript, Ghostview and GSview:
  • http://www.cs.wisc.edu/~ghost/
  • http://www.ghostscript.com [GNU GPL]

Programming

• Suneido [GNU GPL]
• Bloodshed Software (contains a lot of free compilers)
• DJGPP
• ActivePerl, ActivePython, ActiveTCL,...
• MinGW (Minimalist GNU For Windows)
• png2ico [GNU GPL]
• UMLet

• GNAT (GNU Ada compiler)

• flat assembler [Other/Proprietary]
• NASM
• DLX Simulator

• FreeBASIC
• XBasic
• wxBasic
• ScriptBasic
• Yabasic [GNU GPL or Artistic License]

• gcc [GNU GPL]

• DMD
• The GNU D Ccompiler (GDC)
• The LLVM-based D Compiler

• Lazarus

• EiffelStudio
• SmartEiffel
• Liberty Eiffel
• Visual Eiffel
• Gobo Eiffel Compiler
• The Eiffel Compiler / Interpreter (tecomp)

• Open Watcom[Sybase Open Watcom Public License version 1.0]
• g95 [GNU GPL]
• GNU Fortran 95 [GNU GPL]

• Pencil

• Hugs 98
• Helium [GNU GPL]
• The Glasgow Haskell Compiler [Other/proprietary]

• IntelliJ IDEA
• OpenJDK
• jikes
• Dependency Finder
• Ant

• Lua [MIT license]

• Prolog [GNU GPL]

• The Mono project
• DotGNU
• SharpDevelop [GNU GPL]

• Dev-Pascal [GNU GPL]
• Free Pascal
• Inno Pascal
• Lazarus

• Perl
• Strawberry Perl
• Padre

• PHP
• Dev-PHP [GNU GPL]

• GNU Prolog

• Python
• Python for Windows extensions
• PythonCard [BSD]

• Ruby [GNU GPL]

• Rust

• PLT Scheme

• Dev-C++ [GNU GPL]
  • SourceForge page
  • Bloodshed page
• Ultimate++ [GNU GPL]
• Code::Blocks [GNU GPL]
• NetBeans [SPL (Sun Public License)]
• Eclipse [CPL (Common Public License)]
• RHIDE
• WideStudio [MIT/X Consortiun Licence]
• Boa Constructor [GNU GPL]

• x64dbg

• NSIS
• Inno Setup
• FreeExtractor
• UPX
• WiX toolset

• GUI front-ends for CVS [GNU GPL]
• InnoCVS [GNU GPL]
• TortoiseCVS [GNU GPL]

• TortoiseSVN

• TortoiseGit
• Git Extensions
• msysGit

• Boomerang
• JODE
• JReversePro
• DCompiler
• NASM
• HelpDeco
• Radare

• GTK+ (GIMP Toolkit) [GNU LGPL]
• gtkmm [GNU LGPL]
• winGTK
• The Fast Light Toolkit [GNU LGPL]
• wxWidgets
• wxPython [wxWindows License]
• FOX
• The GUI Toolkit, Framework Page

• SDL (Simple DirectMedia Layer) [GNU LGPL]
• Little cms [GNU LGPL]
• Mesa3D [MIT-style license]
• G3D [BSD]
• VTK (The Visualization Toolkit)

• WinPcap (Windows Packet Capture Library) [BSD]
• Allegro [giftware]
• DirectP2P [GNU]
• OpenPTC [GNU LGPL]
• Trivial Portable Framework Library [BSD, GPL, LGPL]
• FFmpeg [GNU LGPL]
• Loris [GNU GPL]
• NTL [GNU GPL]
• Toolbar2000 [GNU GPL]
• IT++ [GNU GPL]
• Blitz++ [GNU GPL]

• ArgoUML
• WhiteStarUML
• Modelio
• Umbrello

• Orbit

Remote access

• PuTTy
• RealTerm
• PCMan
• MindTerm
• Tera Term
• WeirdX
• RealVNC
• TightVNC
• TridiaVNC
• Ultr@VNC
• EchoVNC
• BO2K
• Synergy

Sciences and Math

• OpenStat
• Octave [GNU GPL]
• FreeMat [GNU GPL]
• Scilab
• Yorick
• Maxima [GNU GPL]
• wxMaxima [GNU GPL]
• SAGE
• Axiom
• SciCraft [GNU GPL]
• Yacas [GNU GPL]
• The R Project
• R Commander [GNU GPL]
• SciViews-R [GNU GPL]
• JGR (Java Gui for R) [GNU GPL]
• SciPy [BSD license]
• Rlab (no longer under active development)
• GAP [GNU GPL]
• MayaVi [BSD]
• PARI/GP [GNU GPL]
• Numerical Python
• SalStat [GNU GPL]
• MacAnova [GNU GPL]
• Elmer [GNU GPL]

• GROMACS [GNU GPL]
• GENtle [GNU GPL]
• ClustalX
• GeneDoc
• E-Cell
• Open Bioinformatics Foundation
• BioPython
• BioPerl
• BioJava
• BioRuby
• BioSQL/OBDA
• BioMOBY
• BioDAS
• Artemis [GNU GPL]
• PyMOL [Python License (CNRI Python License)]
• OpenRasMol [Other/proprietary GPL]
• Bioconductor [BSD or GPL]
• Staden [BSD]
• AGM View [GPL]
• AGM Build [GPL]

• QGIS [GNU GPL]
• GRASS GIS [GNU GPL]
• MapServer [Mapserver License]
• GDAL [X/MIT style]
• OpenEV [X/MIT style]
• Thuban [GNU GPL]
• JUMP [GNU GPL]
• Virtual Terrain Project [VTP Software Licence]

More on the FreeGIS site.

• Celestia [GNU GPL]
• OpenUniverse [GNU GPL]
• Stellarium [GNU GPL]
• GNUPlot
• Walnut [GNU GPL/LGPL]
• CopperCore [GNU GPL]
• Gwyddion [GNU GPL]
• Virtual Moon [GNU GPL]

Security, Privacy, Protection,...

• AdBlock
• Adblock Plus
• OpenAntiVirus
• Clam Antivirus
  • Clam AntiVirus [GNU GPL]
  • ClamWin Antivuris [GNU GPL]
  • ClamAV for Windows [GNU GPL]
• GnuPG [GNU GPL]
• Privoxy
• PINs
• GUIDClean
• AxCrypt [GNU GPL]
• Oubliette
• Stunnel [GNU GPL]
• Blowfish Advanced CS
• Stego [GNU GPL]
• Hide In Picture [GNU GPL]
• WinPT [GNU GPL]
• SSHTools [GNU GPL]
• KeePass [BSD License]
• Password Safe [Artistic License]
• SnareWindows [GNU GPL]
• TrueCrypt
• Snare Micro Server [GNU GPL]
• Snare agent for Lotus Notes [GNU GPL]
• Snare for IIS [GNU GPL]
• Snare for ISA [GNU GPL]
• Winpooch
• Tor
• PeerGuardian 2
• Privacy Badger

Server software

• Zope [Zope Public License]
• Plone [GNU GPL]
• NetServer [GNU GPL]
• XAMPP [GNU GPL]

• CVSNT [GNU GPL]

• Dual DHCP DNS Server [GNU GPL]

• Posadis [GNU GPL]
• Dual DHCP DNS Server [GNU GPL]

• FileZilla server
• War FTP Daemon (Version 3) (still very alpha-code!)
• AnomicFTPD [GNU GPL]
• Pure-FTPd [GNU GPL]

• Ident server [BSD]

• jabberd [JOSL and GNU GPL]
• ejabberd [GNU GPL]
• Jive Messenger [GNU GPL]
• OpenIM [BSD]

• Enhydra [Enhydra Public License]

• Hamster (Classic)
• XMail
• shicks! [BSD]
• hMailServer [GNU GPL]

• Apache
• Xitami
• Savant [GNU GPL]
• MyServer [GNU GPL]
• Jigsaw [Other/Prorpietary]
• Analog [GNU GPL]

• WinNFSd [GNU GPL]
• SOSSNT [GNU GPL]

• OpenSSH
• copSSH (different Open Source licenses)

• MRTG (Multi Router Traffic Grapher)
• Squid Web Proxy Cache

SCP (SecureCoPy) clients

• WinSCP
• Secure iXplorer GPL [GNU GPL]

Stream Downloaders

• gmms [GNU GPL]
• mmsclient [GNU GPL]
• JavaMMS [GNU GPL]
• StreamRipper [GNU GPL]
• StationRipper [GNU GPL]
• ASFRecorder [Public Domain]

Text editors

• Vim
• WinVi
• Cream
• GNU Emacs
• XEmacs
• Scintilla and SciTE
• jEdit
• SETEdit
• ht editor
• TeXmacs
• Notepad++
• Programmer's Notepad
• Notepad2
• UniRed
• poEdit
• Metapad

Utilities

• FreeFileSync

• BleachBit
• Little Registry Cleaner
• Bulk Crap Uninstaller
• Safarp
• Eraser

• Open Hardware Monitor
• Process Hacker
• Daphne
• CPUInfo

• MD5summer
• RapidCRC

• base64 by Bob Trower
• base64 by John Walker
• Base64 from ProXoft L.L.C.

• PhotoRec

• Partition Logic
• GParted
• g4u
• WinDirStat

• AstroGrep
• grepWin
• GREP

• agsm [GNU GPL]
• floAt's Mobile Agent [GNU GPL]

• e7NoteIt [GNU GPL]

• zphoto
• ctPhotoBook

• TxtPrint

• Woo Shell

• KDiff3
• Meld
• WinMerge

• AutoHotkey
• JOCR
• HovText
• Sayz Me
• Bid-O-Matic
• Abakt [GNU GPL]
• Really Slick Screensavers [GNU GPL]
• RAMpagew [Other]
• IESpy [Other/Proprietary License]
• DiskWrite [GNU GPL]
• GNU utilities
• Cygwin
• HTMLDOC
• KDiff3 [GNU GPL]
• MP3Ext
• smartision ScreenCopy
• Memtest86 [GNU GPL]
• WCD (Wherever Change Directory) [GNU GPL]
• TreeLine [GNU GPL]
• VirtuaWin [GNU GPL]
• Live View [GNU GPL]
• Win2VNC [GNU GPL]
• tofrodos [GNU GPL]
• Bookmark Manager [GNU GPL]
• BookmarkBridge [GNU GPL]
• Internet Junkbuster [GNU GPL]
• Unison [GNU GPL]
• Ant Renamer [GNU GPL]
• Ant Movie Catalog [GNU GPL]
• dKopie
• Notebox Disorganizer IIe [Public Domain]
• TestDisk [GNU GPL]
• smartmontools [GNU GPL]
• jUploadr [GNU GPL]
• xpy [GNU GPL]
• openbarcodes and its SourceForge project page [GNU GPL]
• Bar code generator [GNU GPL]
• pySIM [GNU GPL]
• Process History

Video capture/processing

• Dr. DivX [GNU LGPL]
• DScaler [GNU GPL]
• VirtualDub [GNU GPL]
• VirtualDubmod [GNU GPL]
• Virtual VCR
• AviSynth [GNU GPL]
• CinePaint [GNU GPL]
• DVD2AVI [GNU GPL]
• AVI-Mux GUI [GNU GPL]
• Avidemux [GNU GPL]
• Filters and tools by Donald Graft [GNU GPL]
• DVDx [GNU GPL]
• Gordian Knot [GNU GPL]
• CamStudio [GNU GPL]
• OBS Studio
• DivFix [GNU GPL]
• FreeVCR [GNU GPL]
• Taksi [BSD]
• NanDub+BRC
  • NanDub+BRC
  • NanDub+BRC Source code
  • official site
• VCDImager [GNU GPL]
• DVD Master Backup [GNU GPL]
• YAAI (Yet Another Avi Info [GNU GPL]
• MediaInfo [GNU GPL, LGPL]
• DivXRepair [GNU GPL]
• mpgtx [GNU GPL]
• HGRip [GNU GPL]
  • sources
  • binaries
• MKVToolnix [GNU GPL]
• SmartRipper [GNU GPL] (the official site
• vstrip [GNU GPL]
• QuEnc AVS->MPEG Encoder [GNU GPL]
• ReJig and it's source code [GNU GPL]
• DVD2AVIdg/MPEG2DECdg Decoding Fix [GNU GPL]
• ChapterXtractor and it's sources [GNU GPL]
• SubRip [GNU GPL]
• MMConvert [GNU GPL]
• ShrinkTo5 [GNU GPL]
• DVDStyler

VJ Software

• gephex [GNU GPL]
• OpenTZT [GNU GPL]
• Video effector [GNU GPL]
• Whorld [GNU GPL]

Web browsers

• Mozilla [NPL/MPL/LGPL/GPL]
• Mozilla SeaMonkey [MPL, NPL]
• Flock [MPL, GPL]
• Beonex Communicator
• K-Meleon
• Firefox
• Lynx (text based!) [GNU GPL]
• Links (text based!) [GNU GPL]
• w3m (text based!) [MIT license]
• AKiller [GNU GPL] (popup killer)

Webcam

• Dorgem

Web editors

• Nvu [MPL/LGPL/GPL]
• Amaya
• Mozilla [NPL/MPL/LGPL/GPL]
• Mozilla SeaMonkey [MPL, NPL]
• HTML Tidy [W3C license]
• JTidy [Other/proprietary license]
• Blue Ice (and its source code) [GNU GPL]
• JGenerator [GNU GPL]
• DRKSpider [GNU GPL]
• KompoZer [MPL, GPL, LGPL]
• ASPForums [GNU GPL]

Webgrabbers and Download Managers

• wget [GNU GPL]
• webfetch [BSD]
• curl [MIT/X derivate license]
• HTTrack [GNU GPL]
• Leech [MPL] (is a Mozilla add-on)
• WackGet [GNU GPL]
• Getleft [GNU GPL]
• QuickDownloader [GNU GPL]
• FlashGot [GNU GPL]
• TrueDownloader [GNU GPL]
• wxDownload Fast [GNU GPL]

Even more open source

• Open Source category at Curlie/DMOZ directory