Combine two CSV files by appending rows or merging by a shared column key. Everything runs in your browser � your data never leaves your device.
Merged CSV will appear here...Load two CSVs and click Merge
Merge your CSV files in three simple steps.
Paste or upload your first CSV into the CSV 1 panel, and your second CSV into the CSV 2 panel. Both files are parsed automatically.
Select Append Rows to stack files vertically, or Merge by Column to join them on a shared key. Configure header handling as needed.
Review the merged output, copy to clipboard, or download as a new CSV file. Your data never leaves your browser.
A CSV Merge Tool is a utility that combines two or more CSV files into a single file. It supports two primary modes: appending rows (stacking one file below another) and merging by column key (joining rows that share a matching value in a specific column, similar to a SQL JOIN).
This tool processes everything in your browser, making it ideal for combining datasets, joining related tables, or consolidating exports from different systems without exposing sensitive data.
Combine related data
Join customer lists, merge product catalogs, or consolidate transaction logs.
Append batch exports
Stack weekly or monthly CSV exports into a single file for analysis.
Enrich datasets
Join lookup tables to add new columns to your main dataset via a shared key.
Prepare data imports
Merge split files before uploading to databases or analytics platforms.
Append Rows stacks CSV 2 below CSV 1, like stacking two sheets of paper. Both files should have compatible headers.
Merge by Column joins rows from both files where a specific column value matches � similar to a SQL JOIN. This requires a shared key column in both files.
Yes. In Append mode, all unique columns from both files are included. Missing values are filled with empty cells (configurable). In Merge by Column mode, matched rows are combined with columns from both files.
Rows from CSV 1 that have no matching key in CSV 2 are included with empty values for CSV 2 columns. Rows from CSV 2 with no match in CSV 1 are excluded.
Yes. The CSV Merger handles files with different columns by creating a union of all headers. Missing columns are filled with empty values. You can also merge by a key column using the merge mode.
For a complete CSV workflow, explore our other free tools:
All processing happens in your browser. Your data never leaves your device.