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Files
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Sheets
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Method
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Match
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Rules
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Columns
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Download
Step 1 of 7 · 🔒 local processing

Merge CSV files online

Choose two or more CSV files. Stack similar exports into one table, or join files by ID, email, SKU or another shared column.
🔒 Local by defaultNormal jobs are processed entirely on your device. Spreadsheet contents are not uploaded.
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Drop CSV files here
or click to browse · CSV files
File size limits

Up to 1 million cells in total across every file you add — roughly 100,000 rows of 10 columns, or about 8 MB of spreadsheet. Also capped at 50 files and 50 MB. Cloud processing is not connected yet; files that exceed local limits are stopped and never uploaded.

Step 2 of 7
Which sheets should we merge?
Choose at least two sheets.
Select the sheets you want to include. A checkmark means selected.
CSV · stay on this step
Step 3 of 7
Choose how to combine the rows
Match columns is the default workflow. Stack Rows skips matching when you only need to append similar lists.
Merge type
Step 4 of 7
Choose your match columns
Required for joins. Choose the column in every sheet that identifies the same record. Nothing is preselected for you.
Match column for each sheet

Choose the column that identifies the same record in each sheet, such as email or Customer ID. Header names can differ. Blank values never match.

Next stepChoose a match column for every sheet to continue.
Step 5 of 7
Choose your matching rules
These rules decide what counts as the same value. They affect matching only — your exported values are never changed.
Step 6 of 7
Choose output columns
All columns are selected. Remove any you do not need, or change their order.
Available columns
Output order — 0
Step 7 of 7 · processed locally
Your merged workbook
Processing…
Merging your files…
Your spreadsheet data is staying on this device.

Merge multiple CSV files in your browser

Use MergeStudio when you have two or more CSV exports that need to become one usable dataset. Choose Stack Rows when the files contain the same kind of records, or use a join when separate CSVs contain different columns about the same customers, orders, products or accounts.

  1. Add two or more CSV files.
  2. Choose Stack Rows to append records, or a join mode to match related rows.
  3. For joins, choose the matching column in each CSV. Header names can differ.
  4. Review matching rules, select the output columns, preview the result and download as CSV or Excel.

Stack CSV files even when the columns are in a different order

CSV exports often contain the same fields in a different order or use slightly different header names. MergeStudio shows column-alignment suggestions before stacking and lets you approve only the mappings that really mean the same thing. Missing fields can remain blank instead of shifting values into the wrong columns.

Join CSV files by ID, email, SKU or another key

Matches Only · inner join

Keep rows whose chosen key appears across every selected CSV.

Master + Enrich · left join

Keep every row from one primary CSV and add matching columns from the others.

Keep Everything · full outer join

Keep matched and unmatched rows from every CSV.

Free CSV merger with local processing

Normal jobs are parsed and merged locally in your browser. MergeStudio does not upload spreadsheet contents for normal processing. Current local limits are up to 1 million cells total, 50 files and 50 MB; oversized jobs are stopped rather than silently uploaded.

Need to combine Excel workbooks too? Use the Excel & CSV merge tool.

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