SpreadsheetFix

Merge multiple CSV files into one

Select two or more CSV files and SpreadsheetFix stacks them into a single file. Columns are matched by header name, so files with different column orders — or a few extra columns — combine correctly.

Free up to 5,000 rows · No sign-up · Nothing uploaded

Drop two or more files to merge

CSV, TSV or XLSX — processed in your browser, never uploaded

Before and after

Before
jan.csv:  email,name
          ana@acme.io,Ana
feb.csv:  name,email,city
          Ben,ben@acme.io,Lyon
After SpreadsheetFix
email,name,city
ana@acme.io,Ana,
ben@acme.io,Ben,Lyon

How it works

  1. 1

    Choose or drop all the CSV files you want to combine.

  2. 2

    SpreadsheetFix lines up columns by header name and adds any column that appears in only some files.

  3. 3

    Optionally remove duplicate rows across files, then download the merged CSV or keep cleaning it.

Columns are matched by name, not position

Copy-pasting files together breaks as soon as one export has its columns in a different order. SpreadsheetFix reads each file’s header row and places every value under the right column. Headers are compared ignoring case and surrounding spaces, so “Email ”, “email” and “EMAIL” line up.

Files with different columns

If one file has a column the others don’t, it’s added to the merged file and left blank for rows from the other files. Nothing is dropped.

Merge, then clean

Monthly exports often overlap. Tick “remove duplicate rows” to de-duplicate across all files while merging, or send the merged file straight into the full SpreadsheetFix cleaner to fix dates, emails and spacing.

Frequently asked questions

How do I combine multiple CSV files into one?

Select all the files in the box above and click Merge. SpreadsheetFix matches columns by header name and gives you a single CSV to download.

What if my CSV files have different columns?

Every column from every file is included. Rows from files that lack a column get an empty value in it.

Can I remove duplicates while merging?

Yes. Enable the remove-duplicates option to drop rows that appear in more than one file.

How many files can I merge?

As many as you like. On the free plan the merged result can contain up to 5,000 rows; Pro allows up to 500,000.

Are my files uploaded?

No. Files are read and merged in your browser. Nothing is sent to a server.

Cleaning bigger files every week?

Pro cleans up to 500,000 rows per file, unlocks all 18 rules, exports to Excel and removes the watermark.

See Pro pricing

Related tools

Remove Duplicates

Delete duplicate rows from a CSV or Excel file in seconds. Exact or key-column matching, a full change log, and your data never leaves your browser.

CSV to Excel Cleaner

Clean up a messy CSV — duplicates, blank rows, spacing, headers, dates — and save it as an Excel-ready file. Private, in-browser CSV to XLSX cleaner.

Fix CSV Encoding

Repair garbled characters like é, ’ and ü in a CSV and convert Windows-1252 files to UTF-8. Free, private, runs entirely in your browser.