Merge CSV Files with Matching Headers
Append the records of a second CSV to a first file with the same headers.
Upload compatible CSVs with matching headers. File order controls row order.
A clear result starts here
Run the tool to see your output here.
Try the example to explore how it works.What to know about this tool
Headers must match exactly, including order and case. This appends rows without joining by key or removing duplicates. Up to 10 MB, 50,000 rows and 200 columns; rectangular CSV with unique nonblank headers required. CSV output has a conservative 20 MB cap.
Instructions and examples
From input to output
- Choose the first and second CSV files, or paste both.
- Leave each input delimiter blank to detect it, or set each source delimiter independently.
- Select Merge CSV files and inspect the resulting rows before downloading.
Settings and result behavior
- This workspace combines exactly two sources by appending the second data rows to the first.
- Headers must match exactly in spelling and order. It does not deduplicate records, join on an ID or resolve conflicting values.
A worked example
- Input
First: id,name 001,Ada Second: id,name 002,Lin
- Settings
- Matching comma-separated headers in the same order.
- Expected result
id,name 001,Ada 002,Lin
Supported input and limits
Choose a UTF-8 CSV, TSV or TXT file, or open “Paste CSV instead”. Use comma, semicolon, tab or pipe separators. A header row with unique nonblank names and the same field count on every row is required. Output uses the first source delimiter, with formula-like cells protected.
Headers must match exactly, including order and case. This appends rows without joining by key or removing duplicates. Up to 10 MB, 50,000 rows and 200 columns; rectangular CSV with unique nonblank headers required. CSV output has a conservative 20 MB cap.
If the result is unexpected
- For a header mismatch, reorder/rename the source columns deliberately before merging.
- If duplicates remain, use CSV cleanup after reviewing whether repeated rows should be removed.
Check before using the result
Check the single header, row total and source order. Review identifiers and protected cells in the destination application.
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