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Duplicate Counter — Free Online Text Tool

Duplicate Counter — Find and Count Duplicate Lines

Paste a list — email addresses, IDs, URLs, log lines, keywords — and click COUNT DUPES to see which lines appear more than once and how many times. SHOW DUPES lists just the repeated lines, and REMOVE DUPES gives you a clean list with every line kept once. It all runs in your browser; nothing is uploaded.

What each button does

Button Output
COUNT DUPES The number of distinct lines that repeat, then each one with its count: "apple": 2
SHOW DUPES Each repeated line once, without counts — ready to copy
REMOVE DUPES The whole list with duplicates removed, keeping the first occurrence and the original order
KEEP DUPES Only the lines that occur more than once, each listed once

For the sample input:

apple
banana
apple
cherry

COUNT DUPES returns:

Duplicate lines: 1
"apple": 2

How lines are compared

Matching is exact, so check these before you trust a "no duplicates" result:

  • Case matters — Apple and apple are different lines. Use the String Case Converter to lowercase everything first if case should not matter (email addresses, for example).
  • Spaces matter — a trailing space makes apple different from apple. Text copied from spreadsheets and PDFs often carries invisible trailing spaces or tabs.
  • Blank lines are ignored by COUNT DUPES and SHOW DUPES, so empty separator lines are never reported as duplicates. REMOVE DUPES keeps a single blank line if the list contained several.

Common uses

  • Clean a mailing list before importing it, so nobody gets the same email twice.
  • Find repeated IDs in an export that should contain unique keys.
  • Spot recurring errors in a log excerpt: the lines with the highest counts are the noisiest.
  • Deduplicate keyword lists and URL lists before a bulk upload.

Tips

  • After REMOVE DUPES, run COUNT LINES to see how many unique entries remain.
  • Run SORT A-Z after removing duplicates for a tidy, alphabetical list.
  • For values separated by spaces or commas rather than lines, convert them to one per line first with SPACE → NEWLINE.