Generate unique avatars. You can use any valid URL like avatar.windsor.io/abcd or avatar.windsor.io/john@doe.com and this app will spit out a .png image you can use as as a placeholder avatar. The same URL will always give you the same image, so this works really well as default profile pictures when you only have a user's ID or email.
We use this throughout windsor.io
Avatars are constructed using these parts