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Text Duplicate Checker

Find repeated lines, sentences, paragraphs, or words without changing the original text. The duplicate text checker lists each repeated item with its count and the positions where it appears.

Runs in your browser. Your data is not uploaded.
Updated

Your text

Settings

Updates as you type for smaller inputs. The original text is never changed.

Duplicates found

Duplicates will appear here
  1. Paste text, upload a file, or load a URL
  2. Choose what to compare and the minimum repeats
  3. Read each match with its count and positions

How to use the Text Duplicate Checker

  1. Paste or type your text, or upload a text file.
  2. Choose what counts as one item: lines, sentences, paragraphs, or words.
  3. Turn on options such as Ignore case or Ignore surrounding whitespace, then set the minimum repeats if needed.
  4. Read the duplicate list to see what repeats, how many times it repeats, and where it appears.

How it works

The text is split into items based on the unit you choose. Each item is then normalized with your options before comparison. For example, with Ignore case turned on, Hello and hello are treated as the same item. With Ignore surrounding whitespace, leading and trailing spaces are removed before matching.

The tool keeps the original item text for display, counts how many times each normalized value appears, and records the position of every match. Positions start at 1, so line 1 means the first line in the text.

Examples

  • In line mode, apple, pear, apple reports apple with count 2 at positions 1, 3.
  • With Ignore case on, Hello and hello are counted together.
  • In paragraph mode, two identical blank-line-separated blocks are shown once with both paragraph positions.

Limitations

  • This tool reports duplicates. It does not remove or rewrite them. Use Remove Duplicate Lines if you want a cleaned result.
  • Sentence splitting follows the browser's sentence rules, so abbreviations such as Dr. can occasionally split in ways you would not expect.
  • When you compare words, punctuation is not returned as a word on its own.
  • Inputs up to 10 MB are supported, and large ones are processed in a worker.

Frequently asked questions

What is the difference between this and Remove Duplicate Lines?

This page only reports repeats and shows where they are. Remove Duplicate Lines actually rewrites the text and keeps one copy of each line.

Can I check duplicate sentences instead of lines?

Yes. Change the unit from lines to sentences, paragraphs, or words depending on what you want to compare.

What do the positions mean?

Positions are the item numbers in the chosen unit. In line mode they are line numbers. In word mode they are word positions.

Often used together with the Text Duplicate Checker.

  • Line Sorter

    Sorts lines A to Z, Z to A, naturally, numerically, by length, or randomly.

  • Diff CheckerDeveloper Tools

    Compares two texts or code files and highlights added, removed, and changed lines.