Local browser tool

Merge CSV Files

Combine UTF-8 CSV files with explicit delimiter and header-mismatch handling.

● Selected files stay on this device

Choose CSV files

Drop files here or browse your device

CSV delimiter

Mismatched headers

Steps

How to use Merge CSV Files

Choose files in row order.
Select delimiter and strict or union header handling.
Download one formula-safe CSV.

Worked example

Combine monthly exports

January has id,name; February adds region. Choose union.

Result: The result uses id,name,region and leaves January’s region empty.

Supported

What this tool handles

Four input delimiters
Strict or union headers
Unicode and formula neutralisation

Not supported

Important limitations

Database joins
Fuzzy header matching
Legacy encodings

Operational limits

2–20 UTF-8 CSV files, maximum 50 MB
100,000 rows and 2,000,000 cells
Output is UTF-8 comma-separated CSV

Troubleshooting

Common problems

Headers do not match

Fix sources in strict mode or choose union for expected differences.

An apostrophe appears

It neutralises a value spreadsheet software could execute.

Questions

Merge CSV Files FAQ

Are duplicate headers accepted?

No, because column mapping would be ambiguous.

Is this a database join?

No. It appends rows and aligns exact headings.

Learn before converting

Practical guides for this task

How to merge CSV files with mismatched columnsChoose strict validation or a deterministic union without shifting data into the wrong headings.CSV encoding, commas, semicolons and tabsDiagnose one-column imports, broken accents and quoted delimiters with a concrete CSV model.