CSV Merger
Merge multiple CSV files into one combined table by matching headers or stacking rows in seconds. Free, no signup, works in your browser.
Everything runs inside your browser — your file is never uploaded to a server.
About this tool
Upload two or more CSV files and this tool combines them into a single dataset, aligning columns by header name so mismatched column order never scrambles your data. It automatically detects shared headers, fills missing values with blanks, and lets you preview the merged result before exporting. Whether you're combining monthly sales exports, joining survey responses from different forms, or stitching together data pulled from several branches of a business, the merger keeps everything in one clean file. Because it runs entirely as JavaScript in your browser, even large CSV files stay private and are never uploaded to a server. Once merged, download the combined CSV instantly or copy it for pasting into a spreadsheet application.
How to use this tool
1. Add your CSV files
Select two or more CSV files from your device to merge.
2. Review matched columns
Check how headers are aligned across the files before merging.
3. Merge
Click merge to combine all rows into one unified table.
4. Download the result
Save the combined CSV or copy it to your clipboard.
Why use this tool
Combining data from multiple sources by hand is slow and error-prone, especially when column orders differ. This tool automates the alignment and merging process instantly, without needing spreadsheet formulas, scripts or a paid data tool, so you get one clean, complete file ready to use.
Tips & best practices
- Make sure header names match exactly (including capitalization) so columns align correctly.
- Check the preview before downloading to catch any unexpected blank columns.
- Merge files in the order you want rows to appear if row order matters to you.
Common use cases
- Combining monthly sales reports exported separately from a POS system.
- Merging survey responses collected from multiple online forms.
- Consolidating inventory lists from different warehouse locations.
- Joining customer lists exported from separate marketing tools.
- Stitching together financial data from multiple branch offices into one report.
Frequently asked questions
Can I merge CSV files with different column orders?
Yes, columns are matched by header name, not position, so files with reordered columns still merge correctly.
What happens if a column is missing in one file?
Missing values are filled with empty cells so the merged table stays aligned and complete.
Is there a limit on how many files I can merge?
No fixed limit; you can merge several files at once, limited only by your browser's memory.
Does merging remove duplicate rows automatically?
No, merging only combines rows; use a dedicated deduplication step afterward if you need unique rows.
Is my data uploaded to a server?
No, all merging happens locally in your browser and your files never leave your device.
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