NextTool

Merge CSV Files

How to use

Combines multiple CSV files into one by appending all their rows together, checking that the headers match across files and warning you if they do not. Upload your files and download the merged CSV.

Excel & CSVLocal only

Step 1 of 3: Upload

  1. 1
  2. 2
  3. 3

Step 1 of 3 · Upload

CSV files to merge (same header assumed)

When to use this
  • Combining several monthly report exports into a single yearly CSV file
  • Stitching together CSV files that were split apart due to a row-count export limit
  • Consolidating data collected from multiple team members into one master file
  • Merging exports from different tools that share the same column structure

Free and private. Everything runs on your own device, with no account and no uploads.

This tool combines multiple CSV or TSV files into a single file by stacking their rows together, using the header row from the first file as the combined header. It is useful for merging several monthly exports or split data files back into one dataset. All files are read and merged directly in your browser, and you get a warning if the files have mismatched headers.

You will see a warning noting that headers differ, and the rows are still merged using the first file's header order, so double-check column alignment afterward.

No, this tool merges plain CSV/TSV text files; binary .xlsx workbooks are not supported.

There is no fixed limit, but merging many large files depends on your browser's available memory.

Yes, each added file has a remove button so you can adjust the list before running the merge.

How it works
  1. 1

    Add two or more CSV files

    Upload at least two files you want to merge.

  2. 2

    Review the file list

    Remove any file you added by mistake before merging.

  3. 3

    Click Merge Files

    The tool combines all rows using the first file's header order.

  4. 4

    Download the merged CSV

    Save the combined dataset to your device.

More in Excel & CSV
CSV Viewer
View and browse CSV files in a clean table layout in browser
CSV Editor
Edit CSV data in an interactive spreadsheet-style table editor
CSV Cleaner
Remove extra spaces, fix encodings, and sanitize CSV data automatically
CSV to JSON
Convert CSV files to JSON arrays with configurable key mapping
Read about this
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Pro tips
  • ·Add files in the order you want their rows to appear, the first file's header sets the column order for the merge.
  • ·Heed the mismatched-headers warning; it usually means columns will be misaligned rather than automatically matched by name.
  • ·Run the CSV Cleaner or Remove Duplicates afterward if the merged file might contain blank rows or repeats.