How to Remove Duplicate Lines from Text
Duplicate lines creep into text files, data exports, log files, email lists, and copied spreadsheet columns. Manually scanning for duplicates is tedious and error-prone. The Duplicate Line Remover handles it instantly.
How to Use the Duplicate Remover
- Open the FlipMyCase Duplicate Line Remover.
- Paste your text with duplicate lines.
- Adjust options (case sensitivity, trim whitespace).
- Copy the deduplicated result.
Common Use Cases
Email Lists
Export email addresses from multiple sources, paste them together, and remove duplicates before importing into your email platform. This prevents sending duplicate messages and keeps your list clean.
Log Files
Server logs often contain repeated error messages. Removing duplicates gives you a clean list of unique errors to investigate.
Data Cleaning
When merging CSV data from multiple sources, duplicate rows are inevitable. Copy a column, deduplicate it, and paste back to get a clean dataset.
Keyword Lists
SEO keyword research tools often output overlapping lists. Combine them and deduplicate to get a comprehensive unique keyword list.
Code Cleanup
Remove duplicate import statements, repeated CSS declarations, or redundant entries in configuration files.
Options Explained
- Case-sensitive: When on, "Apple" and "apple" are kept as separate entries. When off, one is removed.
- Trim whitespace: When on, " hello " and "hello" are treated as the same line. Useful when data has inconsistent spacing.
How It Works
The tool processes your text line by line, tracking which lines it has already seen. The first occurrence is always kept in its original position. Subsequent duplicates are simply removed. This preserves the ordering of your data.
Command Line Alternatives
For very large files, you can use these terminal commands:
- Linux/Mac:
sort -u input.txt > output.txt(sorts and deduplicates) - Preserve order:
awk '!seen[$0]++' input.txt > output.txt
For everyday use with small to medium text, FlipMyCase is faster — no terminal required.