I have a url like so
data:image/jpeg;base64,/9j/4AAQSkZJRgABAQAAAQABAAD/2wCEAAkGBxITEhUUEhQUFRUXGBcVFxgXFxUXGBQYGBYXGBQWFRUYHCggGB0lHBQXITIhJSkrLi4uFyAzODMsN
I will assume you have just the base64 part saved in a variable called data. You want to use Python's binascii module.
from binascii import a2b_base64
data = 'MY BASE64-ENCODED STRING'
binary_data = a2b_base64(data)
fd = open('image.png', 'wb')
fd.write(binary_data)
fd.close()
No PIL needed! (thank goodness! :)