Duplicate Line Remover
Free online tool to remove duplicate lines from text. Keeps the first occurrence of each line, with options for case-sensitive matching and whitespace trimming.
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How to Use
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- 1
Paste your text
Paste or type the text containing duplicate lines you want to remove into the input area.
- 2
Configure options
Enable 'Ignore case' if you want to treat lines like 'Hello' and 'hello' as duplicates.
- 3
Copy the result
Review the result with duplicates removed and click 'Copy' to copy it to your clipboard.
About Duplicate Line Remover
Duplicate Line Remover is an online tool for cleaning up duplicate lines from lists and data. It automatically detects duplicate lines and keeps only the first occurrence. Case-insensitive matching is available, making it useful for mailing lists, log analysis, and data cleanup. When you gather data by copying and pasting from multiple spreadsheets or documents, duplicate entries inevitably creep in. This tool lets you paste the combined list and remove all duplicates in one step, preserving the original order of unique entries. The case-insensitive option handles inconsistent capitalization, treating "Tokyo" and "tokyo" as the same entry. A line count summary shows exactly how many duplicates were removed so you can gauge the state of your data at a glance.
Key Features
- Automatic detection of duplicate lines
- Keeps the first occurrence of each line
- Case-sensitive or case-insensitive matching
- Statistics showing number of removed duplicates
- Real-time result preview
Use Cases
- Remove duplicate email addresses from a mailing list before sending
- Deduplicate rows in a CSV file before importing into a database or Airtable
- Clean up duplicate log entries to focus on unique events
- Consolidate keyword lists from multiple Google Ads campaigns
- Organize bookmarks or URL lists exported from Chrome or Firefox
- Remove repeated lines from configuration files or environment variable lists
FAQ
Which line is kept?
The first occurrence of each line is kept, and all subsequent identical lines are removed. This preserves the original order of unique lines.
How does case-insensitive mode work?
When 'Ignore case' is enabled, lines like 'Hello' and 'hello' are treated as duplicates. In case-sensitive mode, they are treated as different lines.
Can I use this to clean up a mailing list?
Yes. Paste your list of email addresses (one per line), enable 'Ignore case' to catch variations like 'User@example.com' and 'user@example.com', then copy the deduplicated result.
Are blank lines removed?
Blank lines (empty lines) are also subject to deduplication. If there are multiple blank lines, only one will be kept.
Is my text sent to any server?
No. Deduplication runs as JavaScript in your browser. Text data is not transmitted externally.
Are lines with different leading or trailing spaces treated as duplicates?
By default, the full line including surrounding whitespace is compared, so " apple" and "apple" are treated as different lines. If you need whitespace-insensitive deduplication, trim the lines in a text editor first or sort and review them manually before pasting.