Free CSV Data Cleaner — Deduplicate & Fix
Clean messy CSV data instantly — remove duplicates, fix casing, trim spaces, and download clean data.
Drop your CSV file here or click to upload
Processed entirely in your browser — nothing uploaded
Data Analysis
Cleaning Options
Preview (first 20 rows of cleaned data)
How it works
Upload your CSV
Drop a CSV file onto the upload area. Your file is read locally — nothing is sent to any server.
Review data issues
The tool instantly analyses your data and reports how many duplicate rows, empty rows, and whitespace issues it found.
Choose cleaning options
Tick the cleaning operations you want to apply — trim whitespace, remove duplicates, fix casing, fill empty cells, and more.
Download clean CSV
Click Clean Data to apply all selected operations, preview the result, and download the cleaned CSV file.
Common use cases
De-duplicate CRM exports
Remove duplicate customer records from a CRM export before importing into a new system or sending a mailing.
Standardise imported data
Fix inconsistent casing (LONDON vs London vs london) and trim extra spaces from data imported from multiple sources.
Pre-process for analysis
Clean a raw data export before loading it into Excel, Power BI, or a database to avoid errors caused by bad formatting.
Remove empty rows
Strip out blank rows introduced by export tools or manual edits before passing the CSV to an automation pipeline.
Frequently asked questions
Is my data uploaded to a server?
No — all cleaning operations run entirely in your browser. Your CSV data never leaves your device.
What counts as a duplicate row?
A row is considered a duplicate if every cell value is identical to a previously seen row. The first occurrence is kept; subsequent duplicates are removed.
Can I undo cleaning after downloading?
The tool shows a before/after preview and you choose when to download — your original file is never modified. Simply reload the page to start again.
What does "Title Case" do?
Title Case capitalises the first letter of each word in every cell — for example, "john smith" becomes "John Smith".
Can I remove specific columns?
Yes — use the Column Removal option to select which columns to drop from the output CSV.
Does it handle quoted CSV fields?
Yes — the parser correctly handles quoted fields containing commas or newlines, following standard CSV formatting rules.