Duplicate Line Remover

Remove duplicate lines from text, keeping only unique lines.

Category: Text Tools

When to use?

Use it to remove duplicates from a copied keyword or email list. It removes only duplicates while keeping the first-seen order.

How to use

  • Paste the text into the input.
  • Choose whether to be case-sensitive.
  • Copy the deduplicated result.

Input Explanation

Paste a multi-line list (emails, keywords, IDs, etc.).

Calculation Basis

It splits the text into an array by line breaks, then uses a Set/hash to keep only first-seen unique entries while preserving order.

Usage Examples

  • Clean tag/keyword lists - Remove duplicates from a copied keyword list.
  • Dedupe email/ID lists - Remove duplicates from a collected email list.
  • Clean logs - Remove repeated log lines to see only unique messages.

Examples

  • apple, banana, apple, cherry → apple, banana, cherry (duplicate apple removed)
  • A 100-line email list → keeps unique addresses and shows the removed count

Cautions

  • Results can vary by how line-break characters (LF/CRLF) are handled.
  • Lines differing only by spacing are treated as different; tidy spaces first for accurate dedup.

Guides

How dedup works

It splits text into lines and, when identical content appears more than once, keeps the first and removes the rest. Case sensitivity can change the result.

Use for data cleanup

Useful for quickly removing duplicates from email lists, keyword lists, and log data. Pair with the line sorter for more systematic list cleanup.

FAQ

Is dedup case-sensitive?

Case-sensitive by default; turn the option off to ignore case.

Is order preserved?

It keeps the first-seen order and removes later duplicates.

Are lines differing only by spaces seen as duplicates?

Any difference in spacing or characters makes them different lines. Tidy spaces first for accurate dedup.

Can I see how many were removed?

Yes. It shows the number of duplicate lines removed and unique lines remaining.

Related Tools

  • Character Counter - Count characters with and without spaces, and line count, in real time.
  • Byte Counter - Calculate the byte length of text when stored as UTF-8.
  • Case Converter - Convert text, variable names, and filenames to UPPER, camelCase, snake_case, kebab-case, and more.
  • Whitespace Remover - Remove whitespace in various ways — leading/trailing, duplicate, or per-line.
  • Line Sorter - Sort each line of text in ascending/descending order, or shuffle randomly.
  • Markdown Preview - Render Markdown in real time and provide an HTML preview.