Second language writing is a highly complex cognitive activity where learners engage in thinking about the content, planning the language, and executing appropriately to achieve their goals. As classroom language instructors, we would like learners to demonstrate their linguistic knowledge, especially what they newly gained in the classroom, and to be able to critically look at their own writing. I have been developing a web application that can (1) aid learners of Korean language at the intermediate level with practicing the language and (2) motivate them to take a multi-step approach to evaluate their language use, detect potential problems, and make improvements on their own.  This web application, Korean Text Analyzer, automatically analyzes Korean text input and provides instant feedback on various aspects of language use. The automatic feedback consists of general statistics such as number of words and sentences, vocabulary and grammar that are taught in Korean language courses at Princeton (KOR 102, 105, and 107), sentence complexity and lexical diversity, as well as limited feedback on potential errors. In this talk, I will share the process of developing this application, introduce and discuss the textual features that it analyzes, and explore its potential use for students and instructors.