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CSV Merger

Upload multiple CSV files, match fields, and preview the merged result before downloading.

Processed locally · No upload · No sign-up

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CSV file input

Select or drag and drop the CSV files you want to merge (supports multiple files).

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Drag CSV files here or click to upload.

Multiple CSV files are supported.

Files (0)

Uploaded files will appear here.

Four steps

  1. Upload CSV files
  2. Set main table and join fields
  3. Run merge
  4. Download merged result

Technical Description

CSV Merger is a lightweight tool designed specifically for data analysts and operations personnel. It solves the "header alignment" pain point when merging multiple reports. The engine uses index matching technology - even if column orders differ between files, as long as header names are the same, it intelligently categorizes data into the same columns. For large CSV files with thousands of rows, it still maintains millisecond-level merge response speed.

Use Cases

Perfect for data analysts consolidating reports from multiple sources, developers merging exported database tables, operations teams combining user data with transaction records, and finance teams matching invoices with payment records. Also ideal for merging survey results, inventory data, and any scenario requiring multi-source data integration.

User Guide

  1. 1
    Select FilesUpload at least two CSV files and choose which one is the main table.
  2. 2
    Choose Join ColumnsSelect the matching column from the main table and each additional file.
  3. 3
    Choose Join TypeUse left, inner, or full join depending on which rows you need to retain.
  4. 4
    Export DataRun the column-based join, preview the result, and download the merged CSV.

Frequently Asked Questions

What if two files have different numbers of columns?

The tool automatically identifies all column names that appear. For cells with missing data, empty values will be filled automatically.

Does it support different encoding formats (like UTF-8 or GBK)?

Yes. We recommend using UTF-8 encoding to avoid garbled text. The tool automatically attempts to recognize common encodings during import.

Is there a limit on the number of rows after merging?

There is no hard limit on rows, but the smoothness after merging depends on your browser's available memory.

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Free Online CSV Merger - Combine Multiple CSV Files Instantly | YYTools.cc