You can find the .dmg for Xcode and other development tools on https://developer.apple.com/downloads/ which requires Apple ID to login.
*Download Xcode Dmg
How to download XCode for MAC 10.11.6. I am searching for a proper IDE for iOS developement but MAC OS X version is 10.11.6 & because of this I am unable to install XCode. It says 'I should have MAC OS X 10.12+' Xcode Asked by Rihsikesh67. The current version of Xcode can be accessed either through the App store, or the Xcode downloads page. Older versions of Xcode can be found by logging into the Apple Developer Downloads page and searching for the version of Xcode you.
You must login to have a valid session before downloading anything below.Xcode 8
*8.3.2 : https://developer.apple.com/services-account/download?path=/Developer_Tools/Xcode_8.3.2/Xcode_8.3.2.xip
*8.3 : https://developer.apple.com/services-account/download?path=/Developer_Tools/Xcode_8.3/Xcode_8.3.xip
*8.2.1 (Last version supporting OS X 10.11.5 El Capitan) :https://developer.apple.com/services-account/download?path=/Developer_Tools/Xcode_8.2.1/Xcode_8.2.1.xip
*8.2 Beta 2: https://developer.apple.com/services-account/download?path=/Developer_Tools/Xcode_8.2_beta_2/Xcode_8.2_beta_2.xip
*8.1 : https://developer.apple.com/services-account/download?path=/Developer_Tools/Xcode_8.1/Xcode_8.1.xip
*8.0 : https://developer.apple.com/services-account/download?path=/Developer_Tools/Xcode_8/Xcode_8.xip
*8.0 GM seed : http://adcdownload.apple.com/Developer_Tools/Xcode_8_GM_seed/Xcode_8_GM_seed.xipXcode 7
*7.3.1 :https://developer.apple.com/services-account/download?path=/Developer_Tools/Xcode_7.3.1/Xcode_7.3.1.dmg
*7.3 :https://developer.apple.com/services-account/download?path=/Developer_Tools/Xcode_7.3/Xcode_7.3.dmg
*7.2.1(Last version supporting OS X 10.10 Yosemite): https://developer.apple.com/services-account/download?path=/Developer_Tools/Xcode_7.2.1./Xcode_7.2.1.dmg
*7.2:https://developer.apple.com/services-account/download?path=/Developer_Tools/Xcode_7.2/Xcode_7.2.dmg
*7.1 :https://developer.apple.com/services-account/download?path=/Developer_Tools/Xcode_7.1/Xcode_7.1.dmg
*7.1.1: https://developer.apple.com/services-account/download?path=/Developer_Tools/Xcode_7.1.1/Xcode_7.1.1.dmg
*7.0.1 :https://developer.apple.com/services-account/download?path=/Developer_Tools/Xcode_7.0.1/Xcode_7.0.1.dmg
*7.0 :https://developer.apple.com/services-account/download?path=/Developer_Tools/Xcode_7/Xcode_7.dmgXcode 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.dmgXcode 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.dmgXcode 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.dmgDownload Xcode Dmg
References: http://stackoverflow.com/questions/10335747/how-to-download-xcode-4-5-6-7-and-get-the-dmg-file
