Merge multiple CSV files

Select multiple CSV files: headers are merged (union of columns) and all rows are concatenated into a single file. Columns missing from a file are filled with an empty value.

Example:
Drag and drop your files here, or click to browse. 30 MB max per file.

How it works

Handy for consolidating several monthly exports — sales, contacts, orders — into a single file: select all the relevant CSV files (for example "sales_january.csv", "sales_february.csv"…), click "Merge" then download the consolidated file. The files don't need to have exactly the same columns in the same order.

What happens if the files don't have exactly the same columns?

The tool computes the union of all the columns encountered, in the order they first appear. If a file doesn't have a column present in another, the corresponding cells are simply left empty in the result — no row is rejected.

Is there a limit to the number of files?

There is no limit imposed by the tool itself: you can select as many CSV files as needed at once. The only practical constraint is the memory available in your browser for very large volumes.

The merge is performed 100% locally in your browser via WebAssembly: your business data or contacts are never sent to a server.