Hello karan

You can apply for caste validity vertificate both online and offline. However only a few states have the provision of issuing the certificate online.

ONLINE procedure -

You need the visit the online website of the Official Backward Class Welfare Department of your respective state. Then by clicking on the 'Apply for caste certificate online' link you can follow the further procedure.

OFFLINE procedure -

You can visit your nearby Tehsil/Revenue Office and collect a physical copy of the form. After submitting the required documents at the office it usually takes a month to get the caste certificate.

Hope it helps.