Remove Duplicate Lines

Email lists merged from three sources, keyword lists from different SEO tools, product SKUs copied from several reports, URLs collected over weeks — they all end up with repeats. Duplicates mean double emails to the same person, inflated counts and wasted API calls.

This tool removes duplicate lines from any list in your browser. It can treat “Apple” and “apple” as the same, ignore stray spaces at the start and end of lines, drop empty lines, sort the result A→Z, or — the other way round — show you only the items that were duplicated.

The first occurrence of each item is kept in its original position, so the list's order stays meaningful unless you choose to sort.

A summary tells you exactly how many lines were checked, how many are unique and how many were removed, which is useful when you need to report a clean-up (for example, “removed 214 duplicate subscribers”).

Because the list never leaves your browser, it is safe to clean up email addresses, phone numbers or customer IDs that you shouldn't be pasting into an unknown website.

How It Works

1. Paste your list — one item per line. Lists exported from Excel or Google Sheets (a single column) paste in exactly this format.
2. Choose matching rules — case-insensitive matching, trimming spaces, removing empty lines, sorting, or listing duplicates instead of unique values.
3. Remove duplicates — each line is normalised according to your rules and checked against a JavaScript Map of items already seen, which keeps the operation fast even for hundreds of thousands of lines. Copy the result or download it as .txt.

Compatibility & Support

Supported Input → Output Formats

• Input: any list with one item per line — emails, URLs, keywords, names, IDs, lines of a text file
• Output: the de-duplicated (or duplicates-only) list, copy or .txt download
• Options: ignore case, trim spaces, remove blank lines, sort A→Z (natural number order), show duplicates

Unsupported Formats

The tool compares whole lines. It won't match “Ali Khan” with “Khan, Ali”, catch typos, or remove duplicates within a single line of comma-separated values — put one value per line first. For duplicates across multiple spreadsheet columns, use Excel's Remove Duplicates on the table instead.

File Size Limits

No fixed limit. Lists of 500,000+ lines are handled in a second or two on a laptop; very large pastes can be slow on older phones.

If your list lives in a CSV file with several columns, copy only the column you want to de-duplicate. Pasting whole rows works too, but then two rows count as duplicates only when every column matches exactly, which is usually not what you want for email or ID clean-ups.

Who Should Use This Tool?

• Students: A research student de-duplicates a list of paper titles gathered from Google Scholar and a university database before building a bibliography.
• Freelancers & Designers: An SEO freelancer merges keyword exports from three tools and removes duplicates, ignoring case, before clustering them.
• Office Professionals: A marketing assistant cleans a newsletter list combined from event sign-ups and the website form so nobody receives two copies.
• Developers: A developer de-duplicates a list of URLs from server logs and uses “show duplicates” to find the most repeated endpoints.

Why This Tool Beats the Alternatives

• Private processing for email lists and customer data.
• Options for case, spaces and blank lines that basic tools lack.
• Reports exactly how many duplicates were removed.
• Handles very long lists instantly.
• Free and ad-light, no sign-up.

Pro Tips

• For email lists, keep “ignore case” on — email addresses are effectively case-insensitive.
• Paste a column straight from Excel; paste the cleaned list back into the same column.
• To compare two lists (what's in list A but not B), use the Text Compare tool in line mode after sorting both lists here.

Paste your list above and click Remove duplicates.