✅ Free · 🔒 Private · 🚫 No sign-up
CSV Studio: the complete guide
Cromagnon CSV Studio is a free online CSV editor and data-cleaning workspace. Open CSV, TSV and Excel files of any size in a fast grid, see a profile of every column, then clean, filter, sort, deduplicate, split, merge, pivot and chart your data, and export it as CSV, Excel, JSON or a PDF table.
All of it runs on your own device. Customer lists, CRM and shop exports, survey results and bank statements are never uploaded, which also makes big files fast: there is no upload to wait for. No sign-up, no row limit set by us, and no paid plan.
This guide walks through every tool, with tutorials for the most common data-cleaning jobs, tips, shortcuts and an FAQ.
- 100% free
- Handles large files
- Column profiling
- Clean, split, merge, pivot
- No sign-up
- Data stays on your device
Features
Everything you can do in CSV Studio
Open and explore
Fast virtual grid
Scroll through hundreds of thousands of rows smoothly; only the visible rows are drawn.
Any separator and encoding
Commas, semicolons, tabs or pipes, and files in UTF-8 or older encodings, read correctly.
Data Lens
A profile of each column: filled and missing values, unique values, number summary (average, median), date range and the most common values.
Search and filter
Search every row, and add filters per column (equals, contains, greater than and more).
Sort
Sort by any column, and remove the sort to get back the original order.
Charts
Chart a column of labels against a column of values.
Clean
Trim and clean whitespace
Remove leading, trailing and double spaces in one click.
Remove duplicates
Choose whether to ignore case and extra spaces, and whether to keep the first or the last copy.
Remove empty rows
Drop rows that are completely blank.
Find and replace
Across the whole sheet or one column, with match case.
Text tools
UPPERCASE, lowercase and Title Case.
Fill blanks
Fill empty cells down from above, or with a value you choose.
Date normaliser
Rewrite dates written in mixed ways into one format, such as 2026-10-12.
Fix encoding
Re-read a file in another encoding when accents and symbols look wrong.
Reshape
Split a column
Split names, addresses or codes on a separator into several columns.
Merge columns
Join two columns with a separator, such as first and last name.
Add, duplicate, move and rename columns
Including batch rename of every column header at once.
Row numbers
Add a numbered column.
Transpose
Swap rows and columns.
Pivot
Group by rows (and optionally columns) with count, sum, average, minimum or maximum, then download or open as a new tab.
AI sort into categories (optional)
Add a column that sorts rows into categories you describe, using your own AI key.
Split, merge and convert
CSV splitter
Split a big file into several by a number of rows, or one file per value of a column, downloaded as a ZIP.
CSV merger
Combine several CSV files; choose whether to keep columns that only some files have.
CSV to Excel
Download an XLSX with each column typed as text, number or date.
CSV to JSON
With numbers and true/false as real JSON values.
CSV to PDF table
A printable table in portrait or landscape.
Delimiter converter
Save with commas, semicolons, tabs or pipes.
Safe for Excel
Protects cells that start with = + - or @ so they can't run as formulas when opened in a spreadsheet.
Statistics in Math Studio
Send columns to Math Studio for statistics, tests and curve fits.
Tutorials
Step-by-step how-to guides
How to open a large CSV file
- Press Open and choose the CSV (or drag it in).
- CSV Studio detects the separator and encoding.
- Scroll, search and filter right away; nothing is uploaded.
💡 Tip: If accents look wrong (é instead of é), change the encoding in the file options and read it again.
How to remove duplicate rows from a CSV
- Open the file and press Deduplicate.
- Choose to ignore case and extra spaces if needed.
- Choose to keep the first or the last copy.
- Download the cleaned CSV.
How to split a CSV into smaller files
- Open the CSV Splitter.
- Choose rows per file, or one file per value of a column.
- Press Download split ZIP.
💡 Tip: Every row is included, in the current sort order, so sort first if order matters.
How to merge several CSV files
- Open the CSV Merger and choose the files.
- Decide what to do with columns that only some files have.
- Merge and download, or open the result as a tab.
How to convert CSV to Excel
- Open the CSV.
- Open CSV to Excel and set each column to text, number or date.
- Press Download XLSX.
💡 Tip: Set phone numbers and ID codes to Text so Excel keeps their leading zeros.
How to make a pivot table from a CSV
- Open CSV Pivot.
- Choose the rows, optional columns, the values and the calculation.
- Download the summary as CSV or open it as a new tab.
How to split full names into first and last name
- Click the name column.
- Open Split Column and split on a space.
- Rename the new columns First name and Last name.
How to fix mixed date formats
- Open the Date Normalizer and choose the date column.
- Tell it how the dates are written now.
- Choose the new format and apply.
Tips and tricks
Get more out of CSV Studio
Profile before you clean
Open Data Lens first: missing values, duplicates and odd types tell you exactly what to fix.
Trim first, dedupe second
Stray spaces make identical rows look different. Clean whitespace before removing duplicates.
Keep leading zeros
Phone numbers, postcodes and IDs should be Text, not Number, when you export to Excel.
Protect shared files
Turn on Safe for Excel when a file came from a web form, so a cell like =HYPERLINK(...) can't run in someone's spreadsheet.
Filters stack
Add several filters to narrow down rows, then download just the rows shown.
Undo is always there
Every change can be undone with Ctrl + Z, so experiment freely.
Work faster
CSV Studio keyboard shortcuts
Shortcuts don't fire while you are typing in a text box, except Ctrl + S. On a Mac, use ⌘ instead of Ctrl.
Privacy
Private by design: your files stay on your device
Many online CSV tools upload your file to process it. CSV Studio reads, cleans and converts the file inside your browser; the data never leaves your device.
That matters for customer lists, email exports, payroll and anything covered by data-protection rules: nothing is shared with Cromagnon or anyone else.
The optional AI categories feature only sends the different values of the one column you choose (up to 300) to the AI provider whose key you added yourself, and only when you run it.
Comparison
CSV Studio compared with typical online tools
| Cromagnon CSV Studio | Typical online CSV tools | |
|---|---|---|
| Price | ✅ Free, every feature | Free for small files, then paid |
| File size | ✅ No limit set by us | Often a few MB on free plans |
| Where data is processed | ✅ On your device | Uploaded to their servers |
| Clean, split, merge, pivot in one place | ✅ Yes | Usually separate tools |
| Column profiling | ✅ Yes | Rare |
| Export to Excel, JSON, PDF | ✅ Yes | Varies |
Made for everyone
Who uses CSV Studio?
Analysts
Profile and clean exports before analysis.
Marketers
Clean email lists, remove duplicates and split names.
Shop owners
Fix product and order exports from online stores.
Developers
Convert CSV to JSON and inspect data files quickly.
Researchers and students
Tidy survey results and send them to Math Studio for statistics.
Accountants
Merge bank and payment exports and pivot by category.
Troubleshooting
Common problems and how to fix them
Accents and symbols look broken
The file uses a different encoding. Change the encoding and read it again.
Everything is in one column
The separator is not a comma. CSV Studio detects it, but you can also choose semicolon, tab or pipe yourself.
Excel drops leading zeros
Export to Excel with that column set to Text, or keep the CSV.
Duplicates are not removed
The rows differ by spaces or case. Turn on ignore case and ignore extra spaces.
The browser slows down on a huge file
Close other tabs; everything runs on your device. Splitting the file into parts also helps.
FAQ
Frequently asked questions
Is CSV Studio free?
Yes, every feature, with no sign-up and no paid plan.
How large a CSV can it open?
We don't set a limit. Files with hundreds of thousands of rows open smoothly; the real limit is your device's memory.
Is my data uploaded?
No. Files are read and processed in your browser on your device.
Can it remove duplicate rows?
Yes, with options to ignore case and spaces and to keep the first or last copy.
Can I convert CSV to Excel or JSON?
Yes. Download XLSX with column types, JSON with real numbers and booleans, or a PDF table.
Can I split or merge CSV files?
Yes. The splitter makes a ZIP of smaller files and the merger combines several files.
What separators are supported?
Comma, semicolon, tab and pipe, detected automatically or chosen by you.
Why do characters look strange?
The file uses another encoding. Change the encoding and read it again.
Can I make a pivot table?
Yes. Group by rows and columns with count, sum, average, minimum or maximum.
What does Safe for Excel do?
It stops cells that start with = + - or @ from running as formulas when the file is opened in a spreadsheet app.
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