When uploading a post, instead of uploading a file you may supply a direct image URL. In order for this to work, the image must be hosted on a domain that is whitelisted by e621.

View whitelisted domains

Admins

When submitting a new entry, an asterisk (*) may be used to match zero or more, a question mark (?) will match exactly one. Wildcards should only be used to match subdomains (such as *.example.com) and parts of the url. It is unsafe to match part of a domain itself! For example, the pattern *example.com allows an attacker to create a domain like badexample.com to gain access to our IP address. For more information on pattern matching, review the Rails documentation for File.fnmatch.

All whitelist entries are normalized to lowercase character, and matching is not case sensitive.
Any entries marked as hidden will not be visible to the public.
Admins and up are not susceptible to the whitelist, and as such are able to upload from any domain.