Free tool
Clean up a domain list.
Paste anything that has domains in it: a registrar export, a spreadsheet column, URLs, email addresses or a forum post. You get one clean list, each name reduced to the part you register, with duplicates removed and the yearly renewal bill by extension.
Paste your text to see the clean list.
What the cleaner does
Every word with a dot in it is checked as a domain. A URL keeps only its host, an email address only the part after the @, and a subdomain is reduced to the name you register (blog.example.com becomes example.com).
It runs in your browser. Nothing you paste is sent anywhere, and the same text always gives the same list.