Spreadsheet Cleaner

How it works

1. 1Drop in a CSV or Excel file. It is read entirely in your browser — nothing is uploaded.
2. 2The header row is found automatically, even when there is a title, a logo and a blank row above it.
3. 3Tick the fixes you want. Everything that changes is listed with a count, so you can see what was done rather than trusting it.
4. 4Download the result as a clean XLSX or CSV, ready for whatever refused to import it the first time.

Common questions

How does it find the header row?

It takes the first row with at least two non-empty cells where most of those cells are text rather than numbers. That correctly skips a merged title row, a logo row and blank spacers, which is what usually sits above a real table.

What does "fill merged cells down" do?

When a spreadsheet merges cells vertically, the export writes the value once and leaves the rest blank. Filling down repeats the value in each blank so every row stands alone. It is off by default because it genuinely adds data that was not in the file.

Why are duplicate removal and fill-down off by default?

Because both change meaning rather than just formatting. A repeated row might be a real second transaction. The defaults only do things that are safe: remove what is empty and tidy what is whitespace.

What happens to duplicate column names?

They are numbered — "Date" and "Date (2)" — and blank headers become "Column 3" and so on. Most importers reject a sheet with two identically-named columns, so this is usually what was breaking the import.

Is my file uploaded?

No. This tool reads and rewrites the file entirely in your browser. Nothing is sent to a server at any point, which matters when the spreadsheet has real names or figures in it.

Does it fix dates?

Real Excel dates are preserved as dates and exported in ISO form. Text that merely looks like a date is left alone — guessing between day-first and month-first on a whole column is the kind of silent change that causes worse problems than it solves.