Hi I am trying to create a suitelet which uploads budget records. is it feasible through Netsuite?

Yes, it is definitely possible. Create a Suitelet that allows file uploads, then parse the budget data from CSV or Excel files. Use record.create() to build budget records. The challenging part is mapping your upload format to NetSuite's budget structure; you need to manage subsidiary, department, class, and account dimensions correctly. Use the budget record type in SuiteScript and loop through the parsed data to create each budget line. Ensure your upload validation identifies any dimension mismatches before you create the records.