- Open Steam
- Right click on Garry's Mod
- Select Properties
- Select Local Files
- Click Browse
- Open the Garry's Mod folder (follow the steps above)
- Go to the binfolder- Within this folder, you should find gmad.exe,gmad_linuxor something similar on Mac.
- You should also find gmpublish.exe,gmpublish_linuxor something similar on Mac.
 
- Within this folder, you should find 
- Open the Garry's Mod folder (follow the steps above)
- Go to the garrysmodfolder
- Go to the addonsfolder
On Windows, your paths may look like the following:
- C:\Program Files (x86)\Steam\steamapps\common\GarrysMod\bin\gmad.exe
- C:\Program Files (x86)\Steam\steamapps\common\GarrysMod\bin\gmpublish.exe
- C:\Program Files (x86)\Steam\steamapps\common\GarrysMod\garrysmod\addons
On Linux, your paths may look like the following:
- /home/badger/gmod/garrysmod/bin/gmad_linux
- /home/badger/gmod/garrysmod/bin/gmpublish_linux
- /home/badger/gmod/garrysmod/garrysmod/addons
On Mac, your paths may look like the following:
- /Users/Badger/Library/Application Support/Steam/steamapps/common/garrysmod/bin/gmad_mac
- /Users/Badger/Library/Application Support/Steam/steamapps/common/garrysmod/bin/gmpublish_mac
- /Users/Badger/Library/Application Support/Steam/steamapps/common/garrysmod/garrysmod/addons


nuh uh, after an update the location of addons have changed and now they are now located in
"Steam\steamapps\workshop\content\4000"
And also, each folder now is represented by Addon's ID instead of mods name, frickin usless, i hate this change