On national lines, you just have to produce proof of your identity (health insurance card with picture of yourself, driving licence or any other document issued by a public administration bearing the surname, first name, date and place of birth, picture resembling the holder and the identification of the authority that issued the document).
For trips abroad, we remind you that a national ID card or passport may be required in the event of border checks.
If you don't have the necessary documents, you won't be allowed to get on your BlaBlaBus.
To find out which documents are required to cross borders, check the Europe portal.