Remove Duplicate Rows from CSV
Find rows that repeat in the columns that matter and keep just one.
How to use the Remove Duplicate Rows from CSV
- Open a CSV file, drop it onto the panel, or paste rows copied from a spreadsheet.
- Pick the columns that decide whether two rows are the same: click the column names, or type them as a list such as email, 3. Leave the box empty to compare whole rows.
- Choose whether the first or the last copy survives, and whether letter case and surrounding spaces should be ignored.
- Check the counts and the preview, then download the cleaned file. The removed rows can be downloaded as well.
About this tool
A plain text deduplicator only sees whole lines, so two customer records look different as soon as one has a trailing space, a capital letter in the email address or another sign-up date. This tool understands CSV. It parses every row into cells, quoted commas and all, and lets you say which columns identify a record: the email alone, an order number plus a date, or every column. Rows that agree on those columns are duplicates even when the rest differs.
You decide which copy survives. Keeping the first occurrence suits chronological exports; keeping the last one is right when later rows carry newer data. Comparisons can ignore letter case and the spaces around values, which catches most of the variants that creep in through manual entry. The result shows how many rows were read, kept and removed, with a preview of both groups, and the removed rows can be saved separately so nothing disappears without a record.
Files are streamed in blocks and only the comparison keys are held in memory, so lists with millions of rows are fine. For a simple list of lines without columns, the Remove Duplicate Lines tool is the quicker choice.
Frequently asked questions
How is this different from Remove Duplicate Lines?
That tool compares complete lines of text. This one parses the CSV properly and compares chosen cells, so it can match on an email column alone, cope with quoted commas and line breaks inside cells, and report exactly how many rows went.
How do I choose the columns?
Click the column chips under the file, or type a comma separated list of names or numbers into the box, for example email, 3 or 2-4. An empty box compares whole rows. A name that contains a comma goes in quotes.
Which copy of a duplicate is kept?
The first occurrence by default, which keeps the earliest row of an export. Switch to the last occurrence when later rows are more up to date, such as repeated status updates for the same order.
Is my CSV uploaded?
No. The file is read block by block inside this page and never leaves your device, so customer or employee lists stay private. The cleaned file is put together locally too.
How large a file can it handle?
Files of a few hundred megabytes work on a normal laptop, because only the comparison keys of the rows are kept in memory. Progress is shown while the file is being read.