Literably supports grading levels enabling you to either choose your students reading levels or you can let the tool do the work for you. Besides helping you with the administration, scoring, and tracking of your students reading progress, Literably also generates insigthful reports about your students literacy skills to share with parents.
Note that Literably is not free but you can always schedule a demo and try it out to learn more about it. You can also watch the video in this page to see Literably in action.