You can find the Dmgs for Xcode and other development tools onhttps://developer.apple.com/downloads/(requires Apple ID to Login).
You must login to a valid session before downloading anything below. Xcode 6 6.4: http://developer.apple.com/devcenter/download.action?path=/developer_tools/xcode_6.4/xcode_ 6.4.DMG 6.3.2: http://developer.apple.com/devcenter/download.action?path=/developer_tools/xcode_6.3.2/ XCODE_6.3.2.DMG 6.2: http://developer.apple.com/devcenter/download.action?path=/developer_tools/xcode_6.2/ XCODE_6.2.DMG 6.1.1: https://developer.apple.com/devcenter/download.action?path=/developer_tools/xcode_ 6.1.1/XCODE_6.1.1.DMG 6.0.1: https://developer.apple.com/devcenter/download.action?path=/developer_tools/ XCODE_6.0.1/XCODE_6.0.1.DMG Xcode 5 5.1.1: https://developer.apple.com/devcenter/download.action?path=/ DEVELOPER_TOOLS/XCODE_5.1.1/XCODE_5.1.1.DMG 5.0.2: https://developer.apple.com/devcenter/download.action? PATH=/DEVELOPER_TOOLS/XCODE_5.0.2/XCODE_5.0.2.DMG Xcode 4 4.6.3: https://developer.apple.com/devcenter/ Download.action?path=/developer_tools/xcode_4.6.3/xcodE4630916281A.DMG 4.5.2: https://developer.apple.com/devcenter/download.action?path=/developer_tools/xcode_ 4.5.2/XCODE4520418508A.DMG 4.4.1: https://developer.apple.com/devcenter/download.action?path=/developer_ TOOLS/XCODE_4.4.1/XCODE_4.4.1_6938145.DMG 4.3.2: https://developer.apple.com/devcenter/download.action? PATH=/DEVELOPER_TOOLS/XCODE_4.3.2/XCODE_432_LION.DMG 4.2: http://developer.apple.com/devcenter/ DOWNLOAD.ACTION?PATH=/DEVELOPER_TOOLS/XCODE_4.2_FOR_LION_21264/INSTALLXCODE_42_LION.DMG 4.1: http:// Developer.apple.com/devcenter/download.action?path=/developer_tools/xcode_4.1_for_lion_21263/installxcode_41_ LION.DMG 4.0.2: http://developer.apple.com/devcenter/download.action?path=/developer_tools/xcode_4.0.2_and _IOS_SDK_4.3/XCODE_4.0.2_AND_IOS_SDK_4.3.DMG even older Versions 3.2.6: http://developer.apple.com/devcenter/ DOWNLOAD.ACTION?PATH=/DEVELOPER_TOOLS/XCODE_3.2.6_AND_IOS_SDK_4.3__FINAL/XCODE_3.2.6_AND_IOS_SDK_4.3.DMG 3.1.4: http://developer. apple.com/devcenter/download.action?path=/developer_tools/xcode_3.1.4_developer_tools/xcode314_2809_ DEVELOPERDVD.DMG 3.0: http://developer.apple.com/devcenter/download.action?path=/developer_tools/xcode_3.0 /XCODE_3.0.DMG 2.5: http://developer.apple.com/devcenter/download.action?path=/developer_tools/xcode_2.5_ DEVELOPER_TOOLS/XCODE25_8M2558_DEVELOPERDVD.DMG 2.4.1: http://developer.apple.com/devcenter/ DOWNLOAD.ACTION?PATH=/DEVELOPER_TOOLS/XCODE_2.4.1/XCODE_2.4.1_8M1910_6936315.DMG 2.3: http:// Developer.apple.com/devcenter/download.action?path=/developer_tools/xcode_2.3/xcode_2.3_8m1780_oz693620813.dmg 2.2.1: http://developer.apple.com/devcenter/download.action?path=/developer_tools/xcode_tools_2.2.1/xcode _2.2.1_8G1165_018213632.DMG 1.5: http://developer.apple.com/devcenter/download.action?path=/developer_ Tools/xcode_v1.5/xcode_tools_1.5_cd.dmg.bin 1.0: http://developer.apple.com/devcenter/download.action?path =/mac_os_x/mac_os_x_10.3_build_7b85/7b85_xcoDe_cd.dmg
(Newest on top.) For each minor version (6.3, 5.1, etc.) only the latest revision are kept in the list.)
Reference: Http://stackoverflow.com/questions/10335747/how-to-download-xcode-4-5-6-and-get-the-dmg-file