Yes, CommonLit does offer a free diagnostic pre-assessment!
The CommonLit Pre-Assessment was first piloted in the fall of 2019, and will be available again for the fall of 2020 for grades 3-12. The diagnostic is designed to provide teachers with baseline data about their students' performance across specific standards compared to their grade-level peers. Teachers can then use the data to help inform instruction and differentiation needs at the beginning of the school year.
The pre-assessment will only be available from August to November 2020, and it is not currently offered on a semester basis. You can find more information on our blog post: CommonLit's Free Pre-Assessment: Actionable Data to Support Instruction.
Note: If your district has chosen to purchase CommonLit’s Interim Assessments, you will not have access to the Pre-Assessment feature on CommonLit.org. Instead, you’ll be able to collect baseline data through the first interim assessment that your district administers.