Remove Duplicate Lines Online - Free Tool

Use this free tool to remove duplicate lines from a pasted list or an uploaded text file in one click. It keeps the first copy of every line, shows how many lines were removed, and lets you ignore case, trim spaces and drop blank lines. It suits keyword lists, URL lists, email lists and logs.

What Does It Mean to Remove Duplicate Lines?

A duplicate line is a line whose full text matches a line that appeared earlier in the same list. Removing duplicates keeps the first occurrence and deletes every later copy, so each unique line appears exactly once.

The comparison covers the whole line, not individual words. "red running shoes" and "red running shoes sale" are two different lines, so both stay. Whether two lines count as identical also depends on the options you choose, such as ignoring uppercase and lowercase differences or ignoring spaces at the start and end of a line.

Command-line users often reach for sort -u or uniq to do this. Keep in mind that uniq only removes duplicates that sit next to each other, so a list has to be sorted first. This page removes repeats anywhere in the list and leaves the remaining lines in their original order.

How to Use the Remove Duplicate Lines Tool

You can clean a list in about ten seconds with the steps below.

1. Paste your text into the box labeled "Paste your text here, one item per line..." or use "Upload a text file" to load a .txt, .csv or .log file. The Lines and Characters counters update as soon as text appears.
2. Tick the options you need: Case Sensitive, Remove Empty Lines, Trim Whitespace and Show Removed Lines (each one is explained below).
3. Click Remove Duplicates. The cleaned list replaces the text in the box.
4. Check the Original, Remaining and Removed counts to confirm the result matches what you expected.
5. If you turned on Show Removed Lines, read the Removed Lines panel and use its Copy button if you want to keep those lines.
6. Optional: click Sort A-Z or Sort Z-A to alphabetize the cleaned list.
7. Click Copy Result, Select All or Download to take the list with you. Use Clear to empty the box and start again.

Because the result overwrites the box, copy your original text somewhere safe first if you may need it later.

What Do the Four Options Do?

Each checkbox changes how lines are compared or what happens to blank lines, so choose them before you click Remove Duplicates.

Default behavior

With Case Sensitive unchecked, the tool ignores capitalization, so "Running Shoes" and "running shoes" count as the same line. With Remove Empty Lines unchecked, blank lines are left exactly where they are and are never treated as duplicates of each other.

Why Trim Whitespace matters

A trailing space is invisible but makes a line different from its twin. Turning on Trim Whitespace removes that difference, and the lines that remain in your output are the trimmed versions.

Worked Example: Cleaning a Keyword List

Imagine you merged keyword exports and ended up with these eight lines, where the fifth line has a trailing space and the fourth and seventh are blank:

• running shoes
• Running Shoes
• trail running shoes
• (blank)
• running shoes (with a trailing space)
• best running shoes
• (blank)
• trail running shoes

With the default settings, line 2 is removed as a repeat of line 1, and line 8 is removed as a repeat of line 3. The trailing-space version on line 5 survives because its text is not an exact match, and both blank lines stay. You get Original 8, Remaining 6, Removed 2.

Now tick Trim Whitespace and Remove Empty Lines and run it again on the original text. Line 5 now matches line 1, and both blank lines are deleted. The output is three lines: running shoes, trail running shoes and best running shoes. The stats read Original 8, Remaining 3, Removed 5. With Show Removed Lines on, the panel explains each deletion, for example "line 2 dupe of 1" followed by the original text.

How Do You Read the Results and Fix Problems?

The three counters tell you whether the cleanup did what you wanted: Original is the line count before, Remaining is the line count after, and Removed is the difference.

• Removed is 0 but you expect repeats: the lines differ in a hidden way. Tick Trim Whitespace first, then check whether Case Sensitive is on when you wanted it off.
• Removed is higher than the number of repeats you saw: blank lines are counted as removed when Remove Empty Lines is on. Open the Removed Lines panel to see which are empty and which are repeats.
• A line vanished that you wanted to keep: case-insensitive matching probably merged two lines that differ only in capitalization. Turn on Case Sensitive and run it again on your original text.
• Remaining equals Original: there were no exact repeats under your current settings, which is a good sign if you expected a clean list.

The Removed Lines panel labels each entry with its line number and the line it duplicated. That makes it easy to spot-check a few entries before you trust a large cleanup.

Who Needs to Remove Duplicate Lines?

Anyone who combines lists from more than one source ends up with repeats, and this tool clears them quickly.

• SEO specialists: merge keyword exports, competitor term lists or search query reports, then deduplicate before grouping keywords into pages.
• Site auditors: clean URL lists before building redirect maps or submitting a crawl list, so no address is processed twice.
• Marketers and sales teams: tidy email, domain or lead lists copied from several spreadsheets. Paste a single spreadsheet column and each cell becomes one line.
• Developers and analysts: shrink .log or .csv exports to unique entries, or prepare a list of unique IDs and SKUs.
• Writers and editors: remove repeated lines in glossaries, tag lists and reference notes.

Once the list is clean, you can add a shared start or end to every line with the Prefix/Suffix Adder, or turn the column into a single row with the Comma Separating Tool. If you want proof of what changed, paste the before and after versions into the Diff Checker.

Best Practices and Common Mistakes

A few habits prevent most bad results.

Choose case handling on purpose

Keyword research usually treats capitalization as irrelevant, so the default works well. URL paths, file names and product codes can be case-sensitive, so turn on Case Sensitive for those. If you need a consistent style before comparing, run the text through Change Text Case first.

Do not confuse sorting with deduplication

Sort A-Z and Sort Z-A only reorder lines. They do not delete anything, and they change the order permanently in the box. Sorting ignores uppercase and lowercase differences, and it treats numbers as text, so 10 comes before 2. If the original order matters, remove duplicates first and sort only when you are done.

Paste one column, not a whole table

Each line is compared as a whole. A CSV row such as "shoes,500,US" only matches another row with the same three values. To deduplicate by one field, paste only that column.

Review before you replace your source

Turn on Show Removed Lines for any list that matters, scan the panel, and only then copy the result into your project. If you spot a mistake, paste your original back in and change the options.

Limitations to Keep in Mind

This page matches exact lines only. It does not catch near matches such as "running shoe" and "running shoes", spelling variants or lines that differ by punctuation. Those stay as separate entries, so you will need to review them by hand.

It also does not remove repeated words inside a line. If your goal is to clean repeated words rather than whole lines, the Duplicate Word Remover is the better fit. Finally, uploads accept .txt, .csv and .log files, so convert other formats to plain text before you paste or upload them.

Paste your list into the box above, pick your options and click Remove Duplicates to get a clean, ordered list with a clear count of what was removed. For more cleanup helpers, browse the Text Utility Tools collection.