A QUICK WALKTHROUGH
How to use this tool
- Choose two to ten CSV files, or paste two inputs.
- Order the selected files and choose their shared delimiter.
- Merge; review the per-file record counts and download the combined file.
How it works
Merge appends data records in input order and writes the first header once. Every file must have identical header names in identical order. A header-only file contributes no data rows. Up to 10 MiB combined input and 50,000 output records are supported.
A practical example
Start with
File A: id,name 1,Ada File B: id,name 2,Sam
What to expect
id,name 1,Ada 2,Sam
Important considerations
Appending is not a database join. If one file has name,id while another has id,name, reorder it with CSV column editor first. Merging does not remove duplicate records.
5 MiB per input · 50,000 records · 200 columns. Input remains in page memory until you reset or leave. Copy and download actions are initiated by you. No tool input is sent to a processing service.
One more useful detail
Can files have different columns?
No. This release blocks schema mismatches instead of silently filling or dropping fields.