Friends, Correctness of GST Number is must to upload your gst return in www.gst.gov.in. Earlier this tool was available in the bottom of the website www.gst.gov.in. But now the same has been changed in the Top Right of the website. Path of the same is given below alongwith picture view.
www.gst.gov.in > Search Taxpayer > Search Migrated Taxpayer. ( No need to login on web)