carbonapps

    Merge CSV Files Online

    Combine multiple CSV files instantly. All processing happens locally in your browser - no upload required, completely free.

    Drop CSV files here or click to browse

    Up to 20 files

    How to Merge CSV Files

    1. 1

      Upload your CSV files

      Drag and drop or click to browse. Upload up to 20 files.

    2. 2

      Choose merge type

      Select vertical to stack rows, or horizontal to join by key column.

    3. 3

      Configure options

      For horizontal merge, select the key column and join mode.

    4. 4

      Merge files

      Click 'Merge Files' to process. All data stays in your browser.

    5. 5

      Download result

      Preview the merged data and download your CSV file.

    Features

    100% Privacy

    All processing happens locally in your browser

    No Upload Required

    Files never leave your computer

    Multiple Merge Modes

    Vertical stacking and horizontal joins

    Advanced Join Options

    Normal, match, and filter join modes

    Up to 20 Files

    Merge multiple CSV files at once

    Free Forever

    No registration, no limits, no cost

    Frequently Asked Questions

    Resources

    Common problems we solve and guides to help you understand CSV merging.

    Excel Row Limit

    Hit Excel's 1,048,576 row limit? Merge without restrictions.

    Google Sheets Cell Limit

    Reached the 10 million cell limit? Process files locally instead.

    Merge Large CSV Files

    Files too large for other tools? No upload limits here.

    How It Works

    Learn how browser-based CSV processing works with complete privacy.