Option 1 - Using Homebrew

This is the easiest way and will provide automatic updates.

1. ruby -e "$(curl -fsSL https://raw.githubusercontent.com/Homebrew/install/master/install)"
   

2. Install adb 

   brew cask install android-platform-tools
   

3. Start using adb

   adb devices
   

Option 2 - Manually (just the platform tools)

This is the easiest way to get a manual installation of ADB and Fastboot. 

1. Delete your old installation (optional)

   rm -rf ~/.android-sdk-macosx/
   

2. Go to your Downloads folder

   cd ~/Downloads/
   

3. Unzip the tools you downloaded

   unzip platform-tools-latest*.zip 
   

4. Move them somewhere you won't accidentally delete them

   mkdir ~/.android-sdk-macosx
   mv platform-tools/ ~/.android-sdk-macosx/platform-tools
   

5. Add platform-tools to your path

   echo 'export PATH=$PATH:~/.android-sdk-macosx/platform-tools/' >> ~/.bash_profile
   

6. Refresh your bash profile (or restart your terminal app)

   source ~/.bash_profile
   

7. Start using adb

   adb devices
   

Option 3 - Manually (with SDK Manager)

1. Delete your old installation (optional)

   rm -rf ~/.android-sdk-macosx/
   

2. Download the Mac SDK Tools from the Android developer site under "Get just the command line tools". Make sure you save them to your Downloads folder.

3. Go to your Downloads folder

   cd ~/Downloads/
   

4. Unzip the tools you downloaded

   unzip tools_r*-macosx.zip 
   

5. Move them somewhere you won't accidentally delete them

   mkdir ~/.android-sdk-macosx
   mv tools/ ~/.android-sdk-macosx/tools
   

6. Run the SDK Manager

   sh ~/.android-sdk-macosx/tools/android
   

7. Uncheck everything but Android SDK Platform-tools (optional)

8. Click Install Packages, accept licenses, click Install. Close the SDK Manager window.

9. Add platform-tools to your path

   echo 'export PATH=$PATH:~/.android-sdk-macosx/platform-tools/' >> ~/.bash_profile
   

10. Refresh your bash profile (or restart your terminal app)

    source ~/.bash_profile
    

11. Start using adb

    adb devices