Duplicate Line Checker
Paste a list with one item per line: the tool shows which lines repeat and where, and gives back a clean list without duplicates.
Privacy and cost
This tool runs in your browser. What you type or paste is not sent to our servers and it costs nothing to use.
How it works
- Paste your list (keywords, URLs, titles, email addresses…) into the text box.
- Pick the options: ignore case, trim spaces, ignore empty lines, sort.
- Copy or download the cleaned list and read the table of repeated lines.
Example
A list of 7 non-empty lines (keyword research ×2, SEO audit ×3 in mixed case, link building ×2), case ignored: 3 unique lines, 4 duplicates removed.
What the result means
The first occurrence of each line is kept and later ones are dropped. The table shows how many times a line repeats and on which line numbers, which helps you fix the source instead of only cleaning the output.
Common problems this tool helps with
- Keyword lists merged from several exports that contain duplicates.
- Repeated URLs in a redirect file or a list of links.
- Hidden duplicates caused by letter case or trailing spaces.
- Lists of titles or tags pasted twice by accident.
Frequently asked questions
Which occurrence is kept?
The first one. The original order is preserved unless you ask for an alphabetical sort.
Are "SEO" and "seo" duplicates?
Yes when "Ignore case" is ticked (the default). Untick it to treat them as different lines.
Is there a size limit?
Yes: about 500,000 characters are analysed, which covers tens of thousands of lines. A notice appears if the text is truncated.
Are my lists sent to a server?
No. Everything runs in your browser.
Related tools
- Duplicate Text ComparisonPaste two versions of a text: the tool computes their similarity, lists the shared sentences and highlights what was added or removed.Free · runs in your browser
- Word CounterPaste or type a text to get its word, sentence and paragraph count, along with an estimate of its reading time.Free · runs in your browser
- Case ConverterPaste text and pick a style: uppercase, title case, sentence case or code formats such as camelCase and kebab-case.Free · runs in your browser
- Stop Word RemoverPaste a text and the tool strips the stop words (articles, prepositions, pronouns…) and keeps the meaningful words, in four languages.Free · runs in your browser
- Keyword Density CheckerMeasure how often your keywords appear in a text and spot the words and phrases you repeat without meaning to.Free · runs in your browser
- N-Gram AnalyzerSpot the word sequences your text repeats most: bigrams, trigrams and longer, ready to export as CSV.Free · runs in your browser