Remove Duplicate Lines
Remove duplicate lines from text with options for case and trimming.
About Remove Duplicate Lines
Useful for cleaning up log files, CSV data, wordlists, and any text with repeated entries. The "trim whitespace" option treats lines that differ only in leading/trailing spaces as duplicates. "Case sensitive" off treats "Apple" and "apple" as the same line.
FAQ
- Does the order of lines change?
- No. The first occurrence of each line is kept; subsequent duplicates are removed. Order is preserved.
- What does "Trim whitespace" do?
- When enabled, two lines that are identical except for leading/trailing spaces are considered duplicates.
- Is my data sent to a server?
- No. All processing happens locally in your browser.
ABOUT THIS TOOL
Paste a list of lines and this tool removes any repeated entries, with options to ignore case differences and trim surrounding whitespace before comparing. Handy for cleaning up email lists, tag clouds, or any exported data with repeated rows. The tool keeps the first occurrence of each line and discards later repeats, preserving your original ordering rather than resorting the list alphabetically. This matters when line order carries meaning, such as a prioritized keyword list or a log file where earlier entries came first chronologically.
HOW TO USE
- Paste your list of lines into the input box, one entry per line
- Toggle the ignore-case option if entries differ only by capitalization
- Toggle the trim-whitespace option to catch duplicates hidden by extra spaces
- Run the tool to see the deduplicated list
- Copy the cleaned list, which keeps original line order minus repeats
COMMON USE CASES
- Merging two exported contact lists and removing repeated email addresses before a mail campaign
- Cleaning a keyword research list that has the same term pasted in multiple times from different sources
- Deduplicating a list of URLs collected from several sitemap exports before a crawl audit
- Tidying a list of tags or categories copied from multiple spreadsheet columns
- Cleaning repeated log lines pasted from a console output before sharing with a teammate
TIPS & COMMON MISTAKES
- Without the trim-whitespace option, 'example.com' and 'example.com ' (with a trailing space) are treated as different lines and won't be merged
- With case-sensitivity on, 'Apple' and 'apple' count as separate entries — turn on ignore-case if your source data has inconsistent capitalization
- The tool only removes exact duplicate lines, not near-duplicates like 'Street' vs 'St.' — those need manual review or a separate normalization step first
- Blank lines count as duplicates of each other too, so a list with several empty lines will get collapsed down to one if any blank line matches another
MORE QUESTIONS
- Does the tool keep the first or last occurrence of a duplicate line?
- It keeps the first occurrence in the original order and removes any later repeats, rather than reordering the list alphabetically or by frequency.
- Can it remove duplicates that only differ by a trailing space or tab?
- Yes, if you enable the trim-whitespace option, lines are compared after stripping leading and trailing whitespace, which catches duplicates that would otherwise look different due to invisible spacing.
- Will it treat 'Apple Inc.' and 'apple inc.' as duplicates?
- Only if you enable the ignore-case option — with case sensitivity on, differing capitalization makes them count as distinct lines.
- Is there a limit to how many lines it can process?
- There's no fixed limit built into the tool, but since it runs entirely in your browser, extremely large lists (tens of thousands of lines) may take a moment longer to process depending on your device.