Remove Duplicate Rows from CSV Online

Drop duplicate rows from a CSV — by the whole row or by a single key column — entirely in your browser. Nothing is uploaded.

Why this matters

Duplicate rows creep into CSVs whenever you merge exports, append new pulls to an old file, or re-run a report. Left in, they inflate counts, double-send campaigns, and break "unique key" imports that reject the second copy of an ID.

Spreadsheet de-dupe is fiddly: Excel’s "Remove Duplicates" silently keeps whichever copy it meets first with no preview, and a stray trailing space makes two identical-looking rows count as different.

TidyCSV shows you exactly how many duplicates it found and lets you choose the key — dedupe on an email or ID column, or on the entire row — keeping the first occurrence. The whole pass runs locally, so a customer list with personal data never leaves your machine.

How to do it with TidyCSV

1. Drag your CSV onto the tool (or paste it in) — it parses in your browser.
2. Turn on "Remove duplicate rows". Leave it as whole-row, or pick one or more key columns (e.g. Email) to dedupe by.
3. Read the before/after counts and the sample of removed rows to confirm the right rows were dropped.
4. Click Export to download the de-duplicated CSV.

Before & after

FAQ

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