Remove Duplicates

Deduplicate rows in CSV, TSV, or JSON. Trim spaces, ignore case, sort, and choose which columns define a unique row.

Format

Trim spaces when comparingIgnore leading/trailing spaces for uniquenessCase-insensitive compareTreat “Alice” and “alice” as the sameTrim spaces in outputWrite trimmed values to the resultConvert output to lowercaseLowercase all cell values in the resultRemove empty rowsDrop rows where every cell is blank

Keep duplicate

Sort result

Sort by column

CSV input

Drop a file or click to browse

or paste data below

Deduplicated CSV

How Remove Duplicates works

What counts as a duplicate

By default, two rows are duplicates when every column matches. That is often too strict for real data. A contact list may have the same email with a different spelling of the name, and you usually want one row per email. Pick one or more key columns and only those are compared; the other columns come from whichever row is kept.

Two options make matching tolerant of common inconsistencies. Trim spaces when comparing (on by default) treats " ana@example.com " and "ana@example.com" as the same. Case-insensitive compare treats ANA@Example.com as the same as ana@example.com. These options affect only the comparison, not the values written out.

Which row is kept

Keep first occurrence keeps the earliest row of each group and drops later copies, so the original order is preserved. Keep last occurrence keeps the values from the latest row of each group, placed where the group first appeared. Use it when later rows are newer, such as an export appended to over time, and you want the most recent values.

The result panel shows how many rows were read, how many were removed, and how many remain, so you can sanity-check the numbers before downloading.

Cleanup options in the output

Separate from matching, you can write cleaned values to the result: Trim spaces in output removes leading and trailing whitespace from every cell, and Convert output to lowercase lowercases every cell. That is useful for email lists, but not for names. Remove empty rows drops rows where every cell is blank before deduplicating.

You can also sort the result A to Z or Z to A by a chosen column, or by the first key column when set to Auto. Input can be CSV, TSV, or a JSON array of objects, and the result is written back in the same format.

Example

The copy with surrounding spaces is removed because trimming is on. The uppercase copy stays until you turn on case-insensitive compare.

CSV input

email,name
ana@example.com,Ana
 ana@example.com ,Ana
ANA@example.com,Ana
raj@example.com,Raj

Output with default options

email,name
ana@example.com,Ana
ANA@example.com,Ana
raj@example.com,Raj

How to use Remove Duplicates

1
Choose CSV, TSV, or JSON, then paste data or drop a file.
2
Select key columns, or leave them empty to compare whole rows.
3
Set trimming, case, keep first or last, and optional sorting.
4
Check the removed-row count, then copy or download the result.

When to use it

Mailing and CRM lists

Merge exports from several sources and keep one row per email address before importing.

Appended log exports

Keep the latest record per ID from a file that has been appended to over time.