Datasets are 10–30% dupes
In real-world contact lists and CSVs, it’s common to find 1 in 5 rows duplicated or near-duplicated—huge waste for mail merges.
Data clutter
Remove Duplicate Lines — Keep Only Unique Lines
Text & Options
0 characters · 0 words · 0 lines
Preview
Tip: Press Ctrl/Cmd + K to focus the text box. Ctrl/Cmd + Enter runs Remove Duplicates.
Why Use a Duplicate Line Remover?
Whether you're cleaning up data lists, preparing code, managing contact information, or simply tidying up notes, duplicate lines can be a nuisance. They can skew analyses, clutter documents, and introduce errors. This tool helps you quickly and efficiently eliminate redundant lines, leaving you with a clean, unique set of data.
How It Works:
This tool processes your text directly within your web browser, ensuring your data never leaves your device. This offers maximum privacy and security. The process is straightforward:
- Input: Paste your text into the box. Each line is considered a separate entry.
- Options:
- Ignore Case: If checked, "Apple" and "apple" will be treated as the same line. If unchecked, they are considered different.
- Trim Whitespace: If checked, leading or trailing spaces/tabs will be removed from each line before comparison (e.g., " hello " becomes "hello"). This helps catch duplicates that only differ by whitespace.
- Processing: The tool iterates through your lines, keeping only the first occurrence of each unique line and discarding subsequent identical ones. The original order of the first occurrence of each unique line is preserved.
- Output: The cleaned text, with all duplicates removed based on your chosen options, will appear in the same text box.
This tool is perfect for quick data clean-up without the need for complex spreadsheet software or online services that require data uploads.
5 Fun Facts about Duplicates
Case can hide clones
“Apple” vs “apple” are identical to humans but not always to software. Case-insensitive dedupe closes that loophole.
Hidden twins
Whitespace is a decoy
Trailing spaces make two lines look the same but sort differently. Trimming before deduping removes those invisible tripwires.
Invisible noise
Order matters
Stable dedupe keeps the first occurrence and drops the rest, preserving the original sequence—crucial for logs and scripts.
Stable wins
Hashing speeds house-cleaning
Tools often hash each line to a set so millions of lines can be deduped quickly without comparing every pair.
Set power