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Merge CSV Files - Combine Multiple CSV Files

Merge multiple CSV files into one master file in your browser. Processing stays in your browser. Files up to 100MB each. Combine CSVs without installing software.

Quick start

Built for combining monthly exports, vendor files, or multiple csvs into one clean dataset.

Everything runs in your browser, so you can test the workflow with sample data when available before using production files.

Output: A single CSV with your source rows combined in order.

  1. 1Add the files in the order you want them combined.
  2. 2Review the file queue and choose any merge options.
  3. 3Process locally, then download the combined CSV.
Preparing your private workspace…

How to Merge Files

  1. 1Upload your CSV or Excel files (drag & drop or click to browse)
  2. 2Files will be combined automatically, keeping all columns
  3. 3Click Download to save your merged CSV file

Why Use This Tool?

  • ✓100% Client-Side Processing - Your data never leaves your browser
  • ✓100MB Per-File Limit - Clear limits for reliable browser processing
  • ✓Worker-backed processing - Keeps the interface responsive for larger jobs
  • ✓Keep All Columns - Automatically combines different column structures
  • ✓No account - No sign-up, no credit card required

Frequently Asked Questions

Is my data safe?

Yes. All processing happens in your browser. Your files are never uploaded to any server. Your data stays on your device.

Can I merge Excel files?

Yes. You can merge both CSV and Excel (.xlsx) files. The tool automatically detects the format and combines them into one CSV file.

Is there a file size limit?

You can merge files up to 100MB each. For files between 50-100MB, you'll see a warning dialog to ensure your browser can handle it.

What if my files have different columns?

No problem! The tool automatically combines all unique columns. Missing values in some files will appear as empty cells.

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