Hi Madhulika,

The URL that a user’s browser is redirected to after successful authentication. As this URL is used for some OAuth flows to pass an access token, the URL must use secure HTTP (HTTPS) or a custom URI scheme. Separate multiple callback URLs with line breaks. The callback URL field has a limit of 2000 characters, cumulatively. If you enter several URLs and they exceed this limit, configure another connected app to manage more callback URLs.

Thanks.