Not sure if this is the right forum or not but here goes anyway.

I have a few paragraphs of text as the "Initial Value" in a form text field. This is a test for new freelance editors. The user must correct mistakes and make changes to the text and submit it. At this point I want the submitted text to be compared to the "Answer Key" text and the results returned to the user in the form of a percentage mark.

First things first. Is there a ready made script (Javascript? PHP? ASP? Java? ??) which will accept form submissions and compare the two text files and output the differences to another file which will then be tabulated and scored according to parameters set by me? If not how hard would it be to do this from scratch. I guess I mean how much would it cost to create such script since my programming skills are minimal.

Is there another way to achieve the end result of a score for the test being returned to the user?