For example, I signup for a service on a website. The website wants my first name, last name, and email address. Normally, I would have to fill in all of these boxes separately. However, I created an app which takes your email address (for example sarahjane@example.com), and converts it into a first and last name by using a modified sliding-window algorithm to maximize the match (I get around 90% accuracy on some test data with 100's of pairs.)

You'd only have to fill in the first email box, and the other boxes (first name and last name) automatically fill in with Sarah and Jane. It can also handle some complex cases (such as johnimble@example.com and converts it to John and Nimble, as "joh" is unlikely to be a name.)

It also properly capitalizes the first and last name based on previous data (e.g. MacDonald, McDonald, deJoan) and correctly places accent marks over your name if needed.

The problem: autofill. Autofill is very popular (included in all major browsers), but I can't find any hard stats on how many people use it. Of course, this would reduce the usefulness of this app to around zero, since all of the information would already exist.

Would you pay for this if you were a website owner? Would you find this useful if someone were to implement this on their website? Perhaps it could customize the login flow after you've entered in your email address (so it'll say "Hi Sarah" after automatically extracting your first name.)