Remove Duplicate Lines
Remove Duplicate Lines
Remove repeated lines while preserving order.
Runs entirely in your browser
How to use this tool
- Fill in the inputs.
- Read the result.
- Copy or download as needed.
About the Remove Duplicate Lines
Remove Duplicate Lines scans a block of text line by line and strips out any line that has already appeared earlier in the list, while preserving the original order of the remaining lines. This is a fast way to clean up lists — email addresses, keywords, log entries, URLs — that have accumulated repeated entries.
An optional "ignore case" setting treats lines that differ only in capitalization as duplicates as well, which is useful when the same value may have been entered inconsistently (for example, "Example.com" and "example.com").
The tool splits your input text into individual lines using line breaks, then processes them one at a time, keeping track of every line it has already seen. The very first occurrence of each unique line is kept in its original position; any later occurrence of that same line is discarded. This preserves your original ordering rather than alphabetizing or otherwise rearranging the list.
When "ignore case" is checked, the tool compares a lowercase version of each line to decide whether it is a duplicate, but it still outputs the line exactly as it originally appeared (including its original capitalization) — only the comparison, not the output, is case-insensitive.
Common use cases
- Cleaning a mailing list or contact list that has accumulated duplicate email addresses or names over time.
- Deduplicating a list of keywords before using them in an SEO or advertising campaign.
- Removing repeated log lines or data entries when reviewing exported logs or CSV-style text.
- Consolidating a list of URLs collected from multiple sources into a single unique list.
- Cleaning up a to-do list or notes document that has repeated items copied in by mistake.
Tips and best practices
- Enable "ignore case" when your list may contain the same value typed with different capitalization, such as email addresses or domain names.
- The order of the first occurrence of each line is always preserved, so if line order matters to you, this tool will not reshuffle your list.
- Leading or trailing spaces on a line are treated as part of the line, so "example.com" and "example.com " (with a trailing space) may not be detected as duplicates unless you trim them first.
- This tool compares whole lines, not individual words, so it is best suited to lists where each line represents one complete item.
