Hello Aspirant,Hope you are doing well

JoSSA (i.e. Joint Seat Allocation Authority) is basically an authority which has been set up by Ministry of Human Resources Development (MHRD) of India. JoSAA is an authority which has the responsibility of managing and regulating the joint seat allocation for the admission of (JEE Mains)/ JEE (Advance) qualified candidates in its participating institutes like IITs, NITs etc. It is a single platform provided for joint allocation of seats in various institutes.

Generally,You can submit the birth certificate instead  of 10th marksheet in JoSAA counselling.But some states may accept and some may not.So before going to counselling it will be better if you check with respective state's official website as what are the documents that are required.

Hope this helps you

ALL THE BEST