Is there a limit on the number of participants or classes I can have?

Participants: 

Each class can have an unlimited number of participants! Keep in mind that if your classes exceed 500 users, you could experience delays. 

Classes: 

You can be a participant or class owner to up to 100 class groups per Remind account. Click Create a class below "Classes owned" to create new classes.

If you don't see this button, you've reached the class limit for your Remind account.