Deduplicating a list by hand is miserable and error-prone. Whether it is an email export, a keyword list or a pile of URLs, a tool can collapse thousands of lines to the unique ones in an instant — but a couple of options change the result, so it is worth knowing them.
Case sensitivity changes the count
Hello@Example.com and hello@example.com are the same address but different text. If you treat the list case-sensitively, both survive; case-insensitively, one is removed. For emails and URLs you usually want case-insensitive; for anything where capitalisation is meaningful, keep it sensitive.
How to do it
- Open the remove duplicate lines tool and paste your list.
- Choose whether to ignore case and whether to sort the result.
- Copy the cleaned list. It never leaves your browser, which matters for lists of real email addresses.
Sort now, or preserve order
Sorting alphabetically makes the result easy to scan, but it destroys any original ordering. If the order carries meaning — a ranked list, a sequence of steps — keep the original order and only remove the repeats.