Please go to Xero Applications page https://api.xero.com/Application/Add , create an application, and in the line 22 set the client_id to Consumer key and client_secret with Consumer secret. The Callback URL must be http://erp.leaf.com.my/webmail/modules/OAuthIntegratorWebclient/Classes/OAuthClient/login_with_xero.php If you want to post to the user timeline, make sure the application you create has write permissions