Image & Data
Remove Duplicates from CSV
Delete duplicate rows from a CSV — whole rows or by key columns — with a count of what was removed.
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Transparent methodology
What the result includes—and what it does not
Built for people cleaning exports where the same record appears more than once.
Calculation method
- 1Rows stream through a hash set: the first occurrence is kept, repeats are dropped, and the removed count is reported before you download.
- 2You can deduplicate by the whole row or by key columns (for example only the email column), which also catches rows that differ in other fields.
Assumptions and limits
- With key-column mode, the first row wins: later rows with the same key are removed even if other cells differ.
- File contents are processed locally and never uploaded; the only telemetry is an aggregate operation counter with no file names, column names or contents.
Worked example
Deduplicating a contact list
Input: 12,400 contacts exported from two systems with 1,832 exact repeats.
Output: 10,568 unique rows and a visible 'duplicates removed: 1,832' count.
How to use it
Three steps. One clear answer.
- 1Enter or paste the values requested by the tool.
- 2Review the input units and choose any relevant options.
- 3Calculate, then copy or download the result you need.
Built for trust
Useful without the friction.
- No registration or paywall before your result.
- Responsive controls for phone, tablet, and desktop.
- Clear assumptions and warnings where estimates have limits.
Frequently asked questions
How does the Remove Duplicates from CSV work?
Rows stream through a hash set: the first occurrence is kept, repeats are dropped, and the removed count is reported before you download. You can deduplicate by the whole row or by key columns (for example only the email column), which also catches rows that differ in other fields.
What should I check before using the result?
With key-column mode, the first row wins: later rows with the same key are removed even if other cells differ. File contents are processed locally and never uploaded; the only telemetry is an aggregate operation counter with no file names, column names or contents.
How current is this page?
The methodology and source notes were reviewed on 2026-07-25. Editable rates and inputs should still be checked against the provider or authority linked below.
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