Is my spreadsheet data uploaded?

No. The file is read and parsed in the browser tab, and any export is generated there too. This is the relevant property for CSV work specifically, because CSV exports are disproportionately customer lists, order histories and payroll data.

Which delimiters are supported?

Comma, semicolon, tab and pipe are all handled, and the delimiter converter exists precisely because European exports frequently use semicolons while the receiving system expects commas. Quoted fields containing the delimiter are parsed correctly rather than split.

How big a CSV can I open?

Files in the tens of megabytes open comfortably on a desktop. The whole file is held in memory and rendered into a virtualised table, so the practical ceiling is your device's memory rather than a limit imposed here.

Can these tools read .xlsx files?

These tools work on delimited text formats: CSV and TSV. For an Excel workbook, export the sheet you need as CSV from Excel, Google Sheets or LibreOffice first; that also forces you to decide which sheet and which range you actually mean.

9 tools · runs in your browser

Excel & CSV

View, edit, clean, merge and convert CSV data in a table rather than in a text editor.

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All Excel & CSV tools

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View and edit · Open a CSV as a table and change it in place.

CSV Editor

Edit CSV data in an interactive spreadsheet-style table editor

CSV Viewer

View and browse CSV files in a clean table layout in browser

Clean and combine · Fix whitespace and encodings, drop duplicates, merge files.

CSV Cleaner

Remove extra spaces, fix encodings, and sanitize CSV data automatically

Remove Duplicate Rows

Detect and delete duplicate rows in any CSV or XLSX file

Merge CSV Files

Merge multiple CSV files by appending rows or joining on a key column

Convert data · Move between CSV, TSV, JSON and other delimiters.

CSV to JSON

Convert CSV files to JSON arrays with configurable key mapping

JSON to CSV

Flatten JSON arrays into CSV rows with automatic header detection

TSV Converter

Convert between TSV (tab-separated) and CSV or JSON formats

Delimiter Converter

Change the delimiter of any delimited text file, comma, tab, pipe, semicolon

Often used alongside these, from other categories.

About these Excel & CSV tools

CSV is the format everything can read and nothing agrees on: delimiters vary, quoting rules vary, encodings vary, and a spreadsheet application will happily mangle a column of long numbers or leading zeros the moment it opens one. Working on the raw data in a table view avoids that entire category of damage. These tools parse the file in your browser, which matters because the CSVs people need to clean are usually exports containing customer records.

Choosing between these Excel & CSV tools

Open a CSV as data before opening it in a spreadsheet

Spreadsheet applications guess at types on import: phone numbers lose leading zeros, long IDs become scientific notation, and anything that looks like a date becomes one. Viewing and editing the file as text-typed columns first means those conversions never happen.

Clean before you merge

Merging files with inconsistent headers, trailing whitespace or mixed line endings produces a file with subtly duplicated columns. Normalising each input first (trim, fix encoding, align headers) turns the merge into a trivial step.

Deduplication needs a definition of duplicate

Two rows that differ only in whitespace, capitalisation or a trailing empty column are duplicates to a person and distinct to a program. Decide which columns define identity before removing anything, and keep the original file until you have checked the result.

JSON and CSV are not the same shape

CSV is strictly rectangular; JSON is a tree. Converting JSON to CSV means flattening nested objects into dotted column names, and converting back does not necessarily reconstruct the original nesting. Round trips are lossy in a way that is easy to miss until it matters.

Questions people ask

Is my spreadsheet data uploaded?: No. The file is read and parsed in the browser tab, and any export is generated there too. This is the relevant property for CSV work specifically, because CSV exports are disproportionately customer lists, order histories and payroll data.
Which delimiters are supported?: Comma, semicolon, tab and pipe are all handled, and the delimiter converter exists precisely because European exports frequently use semicolons while the receiving system expects commas. Quoted fields containing the delimiter are parsed correctly rather than split.
How big a CSV can I open?: Files in the tens of megabytes open comfortably on a desktop. The whole file is held in memory and rendered into a virtualised table, so the practical ceiling is your device's memory rather than a limit imposed here.
Can these tools read .xlsx files?: These tools work on delimited text formats: CSV and TSV. For an Excel workbook, export the sheet you need as CSV from Excel, Google Sheets or LibreOffice first; that also forces you to decide which sheet and which range you actually mean.

Guides on this topic

Merging CSV files whose columns do not line upTwelve monthly exports, one combined file. Two of the months added a column, one renamed another, and a naive concatenation hides all of it.Why your CSV breaks when Excel opens itExcel guesses the type of every cell it opens. Those guesses have corrupted postcodes, product codes and, famously, human gene names.CSV or Excel? Choosing the right format for the jobA file that opens in Excel is not the same as an Excel file. The difference decides whether your formulas, formatting and column types survive.CSV delimiters, quoting and encoding: the three things that break filesA CSV that opens in column A on one machine and correctly on another is not corrupt. The two machines simply disagree about what CSV means.