For security reasons, you as an administrator may wish to limit the URLs from which users can source content that is displayed on your JIRA or Confluence site (e.g. in an External Gadget). The 'Whitelist' is a list of URLs whose content you wish to make available to users of your site.
You can add URLs (or URL patterns) to your whitelist as described below. Alternatively, if your site and users do not have access to the internet, you can choose to 'Allow all URLs' (see below).
Note that URLs for which Application Links are configured are automatically whitelisted, so you do not need to add them to this list.
To configure a whitelist in JIRA, see Configuring the Whitelist.
To configure a whitelist in Confluence, see Configuring a URL Whitelist.