You can whitelist multiple domains, sub-domains or IP addresses.
Separate the entries with commas or by putting each host on a new line.
You can include or exclude the "https://" or "http://" url part.
You can include "localhost" with or without a port to allow API access in your dev environment
To delete a single host from the whitelist pre-pend a "-" in front of it then click on "Update". You can delete multiple entries in this way.
To explicitly remove all hosts from the whitelist, use the "Clear whitelist" button.
Note that changes are cumulative. Eg. if you select all the hosts in the entry form and delete them, then type in a new host and click update all the old hosts will still be there plus the new one.
To edit a host, delete the old value by pre-pending with "-" and add the new value.