I’ve figured out an easy way which allows twitter users to determine and find if someone is following you on twitter or not? You’ll not require any external service or scroll through your followers list to do this task. Check the simple trick below:
Just visit the profile page of the desired twitter user, open drop down menu (next to Lists) and look for option to send Direct message. If there is a Direct message option – means he is following you, and if there is no DM option – means user isn’t following you.
Example: Shown below are twitter profiles of @fatwalletdeals and @MSWindows. Here you can notice, that fatwallet is following us while MsWindows is not following us.
Update - If you’re using New Twitter, then way will be quite different.
Visit the profile page of desired twitter user, and look for a Message box. If there is a Message button – means user is following you, and if there is no Message box – means user isn’t following you.