Merge CSV Files
Merge matching files strictly, align the same headings in different orders, or create an explicit union with missing cells left blank.
Choose CSV files to merge
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Help, examples, limits, and privacy
How do I merge multiple CSV files?
Monthly exports and regional reports often share the same columns but arrive as separate files. Copying them together by hand risks repeated headers, missing rows, and columns moving into the wrong position.
What this tool changes
- Keeps one output header and appends every data row in selected file order.
- Strict mode validates exact order; heading mode aligns exact names; union mode adds new headings explicitly.
- Previews the resulting schema before writing one UTF-8 CSV.
What it leaves alone
- Rows are not sorted, deduplicated, cleaned, or matched by ID.
- Blank or duplicate headings are stopped rather than silently renamed.
- Every source file remains untouched.
How it works
Three explicit modes. Keep strict matching, align the same exact headings in a different order, or choose a union whose missing cells remain blank.
File order is row order. Rows from the first selected file come first, followed by each remaining file.
One header. Repeated heading rows are removed only at the boundary between selected files.
Processed locally. The file stays on your device. Filenames, rows, cells, and worksheet names are never sent to us or analytics.