What happens to merged cells?

As stored, a merged range keeps its value in the top-left cell and blanks elsewhere. Turn on “Fill merged cells down” to repeat the value across the range — the shape lookups and pivots need.

Each formula becomes the result Excel last saved for it. A formula with no saved result reads as blank, and the page tells you how many did, rather than quietly shipping holes.

Does it read hidden sheets?

Yes — they are listed and marked as hidden, and convert like any other sheet.

What about the title rows above my real header?

Report titles and generated-on lines above the widest row are detected as preamble, counted on the page, and left out of the CSV.

Can I get every sheet at once?

Yes — “Download every sheet” saves a ZIP with one CSV per sheet.

Is my file uploaded anywhere?

No. The conversion runs inside this page: when you convert Excel to CSV here, the browser is told to block outbound connections, so nothing can be sent to another server. Keep the Network tab of your developer tools open while you convert Excel to CSV: every request in it goes to this site, and none carries your file.

Convert Excel to CSV — one clean file per sheet

Turn an .xlsx workbook into clean CSVs: every sheet listed, merged cells unmerged, title rows detected, formulas as their values. No upload.

Excel to CSVRunning on your device

Source

Your workbook

or drag one here · it stays on your device

Result

Add an .xlsx workbook. Each sheet previews before it downloads; hidden sheets are listed too.

How this works

Add your workbook. Drop an .xlsx file onto the page.
Pick a sheet. Preview each one; hidden sheets are marked.
Download. Save the sheet as CSV, or every sheet as a ZIP.

What it cannot do

Only the modern .xlsx format is read. The older binary .xls is refused with the way out stated: save it as .xlsx in Excel first.
Dates come out as ISO 8601 (2024-01-31), read from the workbook’s own number formats; other formatting — colours, fonts, column widths — is presentation and does not survive into CSV.
A password-protected workbook cannot be opened here, and the ceiling for unpacked workbook size is stated in the refusal rather than discovered as a frozen tab.

Questions

What happens to merged cells?: As stored, a merged range keeps its value in the top-left cell and blanks elsewhere. Turn on “Fill merged cells down” to repeat the value across the range — the shape lookups and pivots need.
What about formulas?: Each formula becomes the result Excel last saved for it. A formula with no saved result reads as blank, and the page tells you how many did, rather than quietly shipping holes.
Does it read hidden sheets?: Yes — they are listed and marked as hidden, and convert like any other sheet.
What about the title rows above my real header?: Report titles and generated-on lines above the widest row are detected as preamble, counted on the page, and left out of the CSV.
Can I get every sheet at once?: Yes — “Download every sheet” saves a ZIP with one CSV per sheet.
Is my file uploaded anywhere?: No. The conversion runs inside this page: when you convert Excel to CSV here, the browser is told to block outbound connections, so nothing can be sent to another server. Keep the Network tab of your developer tools open while you convert Excel to CSV: every request in it goes to this site, and none carries your file.

Your file is processed in this page and never uploaded — the privacy page shows how to confirm that yourself.

Common problems this solves

VLOOKUP between two files, without the formula — Bring columns from one spreadsheet into another by a shared ID, the way VLOOKUP does — every row at once, unmatched rows listed, nothing uploaded.
Compare two versions of an Excel file, cell by cell — Two versions of the same workbook, and you need the differences: rows added, removed and changed, down to the cell. Two steps in your browser, no upload.
Make a Markdown table from a spreadsheet — Turn a CSV or spreadsheet export into a Markdown table with aligned columns and escaped pipes, ready to paste into GitHub or a wiki. Nothing uploaded.
Excel dates showing as numbers like 45292 — what they mean and how to convert them — A date column full of five-digit numbers is Excel counting days since 30 Dec 1899. The arithmetic, the traps, and a one-click conversion to real dates.
Excel shows #### instead of the value — what it means and what is really in the cell — Number signs across a cell mean the column is too narrow, or the value became a negative date. The value is intact; here is how to see it and keep it.
CSV UTF-8 or plain CSV — which one to save from Excel, and why the accents break — Excel offers CSV and CSV UTF-8. Pick the wrong one and accents and non-Latin names come out as ? or Ã©. Which to pick, and how to repair a file.
Excel says the file is locked for editing — who has it, how to clear it, and how to get at the data now — Excel says someone has the file open, when often it is you, a sync client or a stale lock. What the lock is, how to clear it, and how to read the data now.
The QuickBooks report export: title lines above the heading, subtotal rows, and getting a plain table — A QuickBooks report export carries the company name above the heading and subtotal rows in the data. Strip them here and get a table any tool reads.
The Xero report export: organisation and date-range lines above the headings, and totals in the rows — A Xero report export carries the organisation name and date range above the headings and total rows in the data. Strip them here for a plain table.
Why a German CSV opens as one column — and what 1.234 means — A German export uses semicolons between fields and a decimal comma. Why 1.234 is one thousand, not one point two, and how to convert the file safely.
An Italian CSV: semicolons, decimal commas, and accents that arrive broken — Italian exports use semicolons and a decimal comma, and often arrive as Windows-1252, which is why città shows up as cittÃ . How to read one properly.
Prepare a CSV for Mailchimp: one address per contact, and no stray spaces — Mailchimp wants one email column in a CSV or tab-delimited file, with no spaces around an address. Find the near-duplicates and clean the column here.