How to Merge Multiple CSV Files Into One
Published September 17, 2026 · 3 min read
Combining exports from different sources or different time periods into one CSV is a common data-prep task. This tool merges multiple files, either requiring identical columns or unioning differently-shaped ones together.
Try CSV MergerSteps
- 1
Open the CSV Merger tool
Go to the CSV merger.
- 2
Upload your CSV files
Add two or more files to combine.
- 3
Choose a column-handling mode
Require identical columns across all files, or union by column name to merge files with different structures.
- 4
Merge and download
Get a single combined CSV, optionally with a source-file column added.
Frequently asked questions
Union mode matches columns by name regardless of their order in each source file, so differently-ordered but matching columns still merge correctly.
In union mode, that file's rows simply get an empty value for the column they don't have, rather than the merge failing.
Yes — there's an option to add a source_file column recording which input file each row originated from.
Because merging runs locally, combining sensitive data from multiple internal exports never means uploading any of them to a third-party service.