Remove duplicate lines
Keep the first time each line appears and drop the rest.
- Runs in your browser — your text is never sent anywhere
- No sign-up, no quotas, free to use as often as you like
How it works
Deduplicating a list is a constant small chore: email addresses, product codes, tags, log lines, anything exported and concatenated. Those lists usually contain real data, which is a good reason not to paste them into an unknown website.
What counts as a duplicate
By default two lines match only if they are character-for-character identical after leading and trailing spaces are ignored. That whitespace handling matters more than it sounds — exported lists frequently carry trailing spaces that make visually identical lines differ.
Ignoring capitals
Turn this on for email addresses, tags and anything case-insensitive by nature. Leave it off for codes, passwords and identifiers where capitalisation is meaningful.
Order
The original order is kept by default, with the first occurrence of each line retained. Sorting alphabetically is offered for when the order does not matter and readability does.
Blank lines
Blank lines are left alone rather than collapsed, so paragraph breaks and deliberate spacing survive.
Remove duplicate lines — questions
Does it keep the first or last occurrence?
The first. Later duplicates are removed.
Will it match lines that differ only in capitals?
Only if you turn on ignore capitals. By default the match is exact.
Are blank lines removed?
No. They are left as they are.
Is my list uploaded?
No. Everything runs in your browser.