Remove Duplicate Lines

A duplicate line remover that strips repeat lines from any list while preserving the first occurrence and the original order, with case-insensitive matching and whitespace trimming to catch near-duplicates that look identical.

This tool removes duplicate lines from any list while keeping the original order. Duplicate entries creep into every list that's been merged, exported or copy-pasted more than once: email lists combined from two campaigns, keyword lists from several research sessions, SKU lists from multiple warehouses, log lines, URLs collected across browser sessions. Sending a campaign to duplicated addresses or importing duplicated SKUs causes real problems — bounces, spam complaints, double-counted inventory — so de-duplication is a step worth doing properly.

Paste your list, one item per line, and this tool removes every repeat while preserving the first occurrence and the original order — unlike spreadsheet de-dupe tricks that sort your data as a side effect. Two options handle the common fuzziness in real lists: case-insensitive matching treats "Apple" and "apple" as the same item (essential for email addresses, where case doesn't matter), and whitespace trimming ignores stray spaces and tabs around entries, which are invisible to the eye but make lines technically different.

The de-duplicated list appears instantly, ready to copy back to wherever it came from or download as a text file. Everything runs in your browser — customer emails and commercial lists are never uploaded. For heavier list surgery, combine this with the neighbouring tools: sort the result alphabetically with the text sorter, compare before-and-after versions with the diff checker, or run find-and-replace to normalise formats before de-duplicating so near-duplicates like "+91 98200 12345" and "9820012345" can be caught.