Duplicate line remover
Paste a list with one item per line. Duplicate lines are removed instantly — the first occurrence of each unique line is kept.
Ctrl + L clear | Ctrl + Shift + C copy output
About deduplication
Removing duplicates is one of the oldest jobs in computing. Unix has shipped a dedicated command for it — uniq — since the 1970s, and "dedupe the list" remains a daily task in data work half a century later because duplicates creep in everywhere: mailing lists merged from two sources, keyword research exported from three tools, log files repeating the same warning thousands of times. Duplicates are more than clutter — they skew counts, inflate email costs, and violate the uniqueness constraints databases depend on. A line-based deduplicator is the plain-text version of that database discipline: every line is an item, and every item appears exactly once.
Common uses for duplicate line removal
Cleaning up email lists is one of the most frequent uses — pasting a list of email addresses and removing every duplicate in seconds. SEO professionals use it to deduplicate keyword lists before uploading to tools. Developers use it to find unique values in log output or configuration files. Data analysts paste spreadsheet columns and remove duplicates without needing Excel or a database query. Writers use it to deduplicate word lists and reference lists.
Frequently asked questions
How does the duplicate line remover work?
The tool compares your text line by line — each line break creates a new item — and keeps only the first occurrence of each unique line, removing every identical line that follows. The stats bar shows how many lines you started with, how many are unique, and how many duplicates were removed, so you can sanity-check the result at a glance. Because comparison is per line, paragraph text should be split into one item per line first (the remove line breaks tool does this) before deduplicating.
Is the duplicate detection case sensitive?
By default, no — "Apple", "APPLE" and "apple" all count as the same item and only the first survives, which is the right behaviour for email addresses, domains and most everyday lists. Enable the case sensitive option when capitalization is meaningful, such as lists of code identifiers where "getUserName" and "getusername" are genuinely different values. The trim whitespace option works alongside it, so "apple " with a stray trailing space still matches "apple" instead of slipping through as unique.
Will blank lines be removed too?
Only if you choose. By default blank lines are preserved as part of your list's structure — useful when empty lines separate groups of items you want to keep visually distinct. Enable remove blank lines to strip all empty lines in the same pass as deduplication, which is usually what you want when preparing a list for import into another system that expects one clean item per row.
What happens to the original order of my list?
It is preserved. Each unique line keeps the position of its first appearance, and only the later repeats vanish — so a curated list stays in its curated order after cleanup. This differs from spreadsheet dedupe workflows that often force a sort first. If you do want alphabetical output, enable the sort option and the deduplicated list is reordered A to Z as a final step.
Can I use this to find unique values in a list?
Yes — keeping one copy of every distinct line is mathematically identical to extracting the unique values, the same result as Excel's Remove Duplicates or SQL's SELECT DISTINCT, but without opening either. Paste a spreadsheet column or log output, and the output panel is your unique-value set while the stats bar tells you how many distinct items exist. It is often the fastest way to answer "how many different X are in this data?"