How can we view records of Custom object without launching it as tab in Salesforce ?

Hi Vikas,

You can use the query editor in the developer console to view any object's records, irrespective of if it has been launched as a tab.

For example:

SELECT Id, name, UnitPrice FROM PricebookEntry

Then use the 'open detail page' button for any specific record to view its detail page.

Hope this helps.