Hello Aspirant,

You can upload either state level or central level OBC certificate but the format should be similar to that of available on the official website of JOSAA for which the link is given below :-

https://josaa.nic.in/webinfo/File/GetFile?FileId=11&LangId=P

Now if you don't have your your category certificate of similar format right now then you can submit the undertaking which declares that you will submit the original and valid caste certificate later on at the time of admission. You can download the undertaking from the official portal of NTA, for which link is also given below :-

https://jeemain.nta.nic.in/webinfo2021/File/GetFile?FileId=5&LangId=P

When you visit on the above link you will find a PDF and on page no.9 there is undertaking format which you have to download and after filling it you have to upload it on the place of category certificate in the JEE-Main 2021 Application form.

I hope this information helps you.

Good Luck!!