Remove Duplicate Lines

Removing duplicate lines from a list

Duplicate entries creep into lists from everywhere: merging two exports, copying rows twice, collecting form submissions, or scraping the same item from several pages. Duplicates inflate counts, skew imports, and waste effort. This tool reduces any line-based list to its unique members while keeping the order you pasted, and it tells you precisely how many repeats it took out.

Order-preserving by design

Many dedupe tools sort as a side effect, which scrambles a list you carefully arranged. This one keeps the first occurrence of each value exactly where it was and silently drops the later copies. A priority-ordered backlog, a ranked keyword list, or a chronological log stays in its intended sequence — only the redundancy disappears.

Case sensitivity: when it matters

Whether "Apple" and "apple" are the same depends on your data. For names, tags, and most human-readable lists they are duplicates, so the default case-insensitive mode merges them. For things where capitalisation is significant — case-sensitive usernames, API keys, or programming identifiers — turn Case-sensitive on so only exact matches are removed.

Whitespace is the silent duplicate-maker

The most common reason "identical" lines fail to dedupe is invisible whitespace: a trailing space, a tab pasted from a spreadsheet, or a stray indent. With Trim whitespace on, each line is stripped of leading and trailing spaces before comparison, so visually identical entries are correctly recognised as duplicates. Leave it on unless that surrounding space is genuinely part of the value.

Common uses

• Email and contact lists — collapse repeats before importing into a CRM or mail tool.
• Keyword research — remove duplicate search terms gathered from multiple sources.
• Log and data cleaning — find the set of distinct values in a noisy export.
• Inventory and SKU lists — ensure each product code appears only once.

Fast because it is local

The deduplication is a single pass that records each value it has already seen in a hash set, which is why even a very long list resolves the moment you click. Keeping that pass inside the page has a second benefit beyond speed: a column of customer emails or other sensitive records is compared and trimmed without ever being handed to an outside server.

Related text tools

• Sort Lines — alphabetise or order the list after deduping.
• Extract Emails — pull addresses from text, then remove repeats here.
• Remove Line Breaks — flatten the unique list into one line.
• Word & Character Counter — count the cleaned-up list.