Remove Duplicate Lines
This tool removes duplicate lines from any block of text instantly in your browser. Paste a list, log output, or any multiline content and it filters out repeated lines, keeping only the first occurrence of each unique line. Options let you ignore letter case and trim surrounding whitespace before comparing, so lines that differ only by capitalization or leading/trailing spaces are treated as the same.
You can also sort the resulting unique lines alphabetically for cleaner output. The tool shows the exact count of duplicate lines removed, making it easy to audit your data. Everything runs client-side — no text is ever sent to a server, so sensitive data stays private.
How it works
Each line is compared against a Set of previously seen lines. If the normalized line (optionally lowercased and/or trimmed) is not in the Set, it is kept and added to the Set; otherwise it is discarded. The optional sort step applies localeCompare on the unique results.
Use cases
- Deduplicating email lists or subscriber exports before a campaign
- Cleaning up log files or stack traces that repeat the same error lines
- Removing duplicate entries from CSV or TSV data columns pasted as text
- Preparing unique keyword lists for SEO or pay-per-click ad campaigns
- Filtering repeated lines from code diffs, config files, or shell command output
Frequently asked questions
How do I remove duplicate lines from a list of text?
Paste your list into the input box and the tool instantly keeps only the first occurrence of each unique line. Each line is compared against a Set of previously seen lines and any repeat is discarded. The exact count of removed duplicates is shown so you can verify how many entries were filtered out.
Does removing duplicate lines preserve the original order?
Yes. By default, lines stay in their original order and only later repeats are discarded — the first occurrence of each line is always the one kept. If you prefer alphabetized output, enable the optional sort, which applies localeCompare to the unique results.
Can I ignore uppercase and lowercase differences when deduplicating?
Yes. The case-insensitive option lowercases lines before comparing, so "Apple" and "apple" count as the same line. A separate trim option removes leading and trailing whitespace first, so lines that differ only by surrounding spaces are also treated as duplicates.
Is it safe to paste sensitive data like email lists into this tool?
Yes. All processing runs entirely in your browser — no text is ever uploaded to a server. You can even disconnect from the internet after loading the page and the deduplication still works.
How do I remove duplicates from an Excel or Google Sheets column?
Copy the column and paste it here as plain text — each cell becomes one line. Remove the duplicates, optionally sort, then copy the cleaned result back into your spreadsheet. For quick one-off cleanups this is often faster than building a formula or using the built-in dedupe dialog.