Yes, all your past and new leads will be automatically imported to the selected service when integrating it with Hunter. You can choose between the following integrations:
To check the synchronization status of your leads, simply go to the Leads section and click on a lead. Scroll down to see if the lead has been successfully added to your CRM (the lead will show the tag "Saved").
Please note that the leads are saved only once: any changes on the lead in Hunter afterwards won't be saved to your CRM.