Python + Browser with Mac: Error - 'chromedriver' executable needs to be in PATH

brew cask install chromedriver

The current working command to install chromedriver from brew, since the previously accepted answer has been outdated unfortunately.

This then needs to be paired with your selinium code :

chrome_path = r'/usr/local/bin/chromedriver' #path from 'which chromedriver'
driver = webdriver.Chrome(executable_path=chrome_path)

or 

import os 

driver = webdriver.Chrome(executable_path=os.popen('which chromedriver').read().strip())

Note: you may also need to do : brew cask install google-chrome

or

brew install --cask chromedriver

depending on your version of brew.

The easiest way to resolve this is on a Mac is to:

brew install --cask chromedriver

Splinter and similar frameworks for browser automation rely on external modules being installed and callable in PATH.

Edit: chromedriver migrated from homebrew/core to homebrew/cask