There’s a lot of talk about this web app, Hemingway. If you want to see what it does, just visit the app’s web site and paste in some of your own text to see how it rates. You can even download a desktop version. Hint: write only short sentences.
Of course, there seems to be a lot of reverence for simple sentences these days, especially among those who are fans of Hemmingway, but simple sentences alone cannot sustain good writing. Hemmingway’s prose was poetic, and the simple sentence was refined to an art that’s hardly easy to replicate. It only feels effortless.
As for the app, it will certainly help you write for easy reading, but don’t expect it to comment on the quality of your style.