How do I remove duplicate rows from a CSV?

Upload or paste your CSV, then choose to deduplicate by all columns or by a single key column. By all columns, a row is a duplicate only when every cell matches an earlier row; by a key column, a row is a duplicate when that column's value matches an earlier row. The first occurrence is kept and later duplicates are dropped. Copy or download the cleaned CSV.

What's the difference between 'all columns' and 'a key column'?

All columns flags a row as a duplicate only when every cell is identical to an earlier row. A key column flags a row as a duplicate when the chosen column (e.g. email or ID) matches, even if other columns differ — handy for de-duplicating on a unique key.

For each key, the first row that appears is kept and every later row with the same key is removed. The original order is preserved, so earlier rows win.

Can I see the before and after counts?

Yes. After processing, the tool shows the original row count, the deduplicated row count, and how many duplicates were removed, so you can see at a glance how many duplicates were in your file.

No. Everything runs entirely in your browser. Your CSV is never uploaded or stored on a server.

Yes, it is completely free. No sign-up and no installation required.

CSV row deduplicate

CSV tools

Remove duplicate CSV rows by all columns or by a chosen key column, and see the before/after counts. Everything runs in your browser; your data is never uploaded.

What is this CSV deduplicate tool?

A free, browser-based tool that removes duplicate rows from a CSV. Deduplicate by all columns (a row is a duplicate only when every cell matches an earlier row) or by a single key column such as email or ID. The first occurrence is kept and later duplicates are dropped, and you see the before/after row counts at a glance. It's ideal for cleaning lead lists and CRM exports before importing them elsewhere. Everything runs locally in your browser, so your data is never uploaded.

How to use it

Upload a CSV file or paste it into the box on the left.
Choose to deduplicate by all columns, or by a single key column.
Check the before/after row counts to see how many duplicates were removed.
Copy the result or download it as a new CSV.

Common use cases

De-duplicating a lead list on the email column before an import.
Removing fully identical rows produced by merging several exports.
Collapsing repeated customer IDs to one row each.

Related CSV tools

FAQ

Operated by

Tools by Timothe AI is a suite of free tools built and operated by unbounded pioneering inc, the company behind Timothe AI.

Ryosuke SuzukiFounder & CEO

Founder & CEO of Unbounded Pioneering Inc., the company behind Timothe AI, and an expert in machine learning and AI product development. He began his career in machine learning research at a university laboratory, then designed and built large-scale products as a software engineer at PLAID, Rakuten, and Recruit, while also driving new business development. Now specializing in generative AI and AI products, he works across both engineering and business development, and is a named inventor on multiple granted patents in web technology.

Named inventor on granted patents JP6887648 & JP7480958 · Patent pending on Timothe AI technology

LinkedIn X About us →

Get in touch

Thanks for reaching out

Thank you for your interest in our company. A member of our team will get back to you within one business day.

What we can help with

Adopting and getting the most out of Timothe AI
A demo or trial of Timothe AI
AI adoption in general (beyond our own product, too)
Alliances and partnerships
Any other questions

Talk to us online

You can also book a meeting directly from the calendar.