Remove Duplicate Lines
Paste any text list and strip every repeated line instantly. Choose case-sensitive or insensitive matching, keep the first or last occurrence, and optionally remove blank lines too. Free, private, browser-based.
How to Remove Duplicate Lines
Three steps and your list is clean.
Paste your text
Type or paste any list into the input box — one entry per line. Works with email lists, keywords, URLs, code imports, and more.
Choose options
Select Case Sensitive or Case Insensitive, and whether to keep the first or last occurrence of each repeated line.
Copy the result
Hit Copy to save the unique lines to your clipboard. The footer shows exactly how many duplicates were removed.
About This Deduplication Tool
Duplicate lines creep into lists from database exports, copied spreadsheet columns, merged text files, and repeated copy-paste operations. Removing them by hand is tedious and unreliable. This tool finds and strips every repeated line in a single click.
Case Sensitive mode treats lines as duplicates only when every character matches exactly — "Apple" and "apple" are kept as separate entries. Case Insensitive mode ignores capitalization, so "Error", "error", and "ERROR" are all treated as the same line and only one copy is retained. This is the right mode for email addresses, domain names, and most real-world lists.
Keep First preserves the first occurrence of each line and removes all later repeats — useful when order matters and you want to retain entries in their original sequence. Keep Last removes earlier occurrences and keeps the last — useful when later entries represent updated values that should supersede earlier ones.
The Also remove blank lines toggle strips empty rows before deduplication, giving you a compact, clean output. All processing runs in your browser — your data never leaves your device.
Frequently Asked Questions
What counts as a duplicate line?
A duplicate is any line whose content has already appeared in the text. In case-sensitive mode, every character must match exactly. In case-insensitive mode, capitalization differences are ignored. Leading and trailing whitespace is not stripped automatically — "banana" and " banana" with a leading space are distinct lines unless you remove the extra space first.
What is case-sensitive deduplication?
Case-sensitive deduplication keeps "Error", "error", and "ERROR" as three separate unique lines because their capitalization differs. Case-insensitive deduplication treats them as the same line and retains only one copy. For email addresses, domain names, and most human-readable lists, case-insensitive mode is the correct choice since those values are not case-significant.
Can I use this on email lists?
Yes — this is one of the most common uses. Paste your email list with one address per line, enable Case Insensitive mode, and click to deduplicate. The tool removes any address that appears more than once. Because all processing runs locally in your browser, your contact list remains completely private and is never uploaded anywhere.
Does it work on CSV data?
It works on any line-delimited text. For CSV files where each record is exactly one line, paste the content and the tool will remove identical duplicate rows. If your CSV has a header row, that row will be treated as a regular line — it will be kept only once if it appears more than once. For deduplication by a specific column value, a spreadsheet tool is more appropriate.
Is data stored when I use this tool?
No. All processing happens entirely in your browser using JavaScript. Your text is never sent to any server, stored in a database, or seen by anyone. You can safely deduplicate confidential lists — email addresses, API keys, internal IDs, or any sensitive content — with no privacy risk whatsoever.
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