Quickly answer your question "Is CommonLit down?" using CommonLit's Status page.
If you are ever in doubt of whether CommonLit is experiencing a service disruption, you can track CommonLit's status and sign up for disruption alerts at: https://status.commonlit.org/.
CommonLit will also report outages in its third party integrations - Google SSO, Clever SSO, and Google Classroom coursework API - here. If Google SSO or Clever SSO is down, any student or teacher can sign into CommonLit using their email (or username, for students) and backup CommonLit password.
Teachers and students with emails can request your backup CommonLit password here: https://www.commonlit.org/en/password_reset_requests/new.
Teachers can also reset student's backup passwords from their View Students page.