XLSX to CSV
Convert an Excel workbook into comma-separated values — one file per sheet. Shared strings, numbers, booleans, dates and inline text are all resolved correctly, and the result opens cleanly in Sheets, Numbers, a database import or a script. Parsed in your browser, never uploaded.
Excel stores dates as a day count from 1899. Furtu recognises the built-in date formats and writes ISO dates; custom formats it does not recognise stay as numbers.
Turning this off drops rows where every cell is blank.
Off means only values containing a comma, quote or newline are quoted, which is what most importers expect.
CRLF is what Excel writes and what most Windows tools expect.
How xlsx to csv works
- Add your workbookDrop in a .xlsx. Furtu reads the workbook part to find the sheet names, then resolves each relationship to the matching sheet XML.
- Set the output optionsChoose which sheets to export, whether dates become ISO dates, and how values are quoted and terminated.
- Download the CSVsOne file per sheet, listed with its row and column count so you can sanity-check the export before you rely on it.
What you get
Export a spreadsheet to CSV so anything can read it. Everything happens inside this page: the file is read by your browser, transformed in memory and handed straight back to you as a download. There is no upload queue, no waiting for a server, and nothing left behind when you close the tab.
Supported formats
Furtu accepts .xlsx files up to 100 MB each — one file at a time.
- Every file is checked against its real file signature, not just its name, so a renamed or corrupt file is rejected with an explanation instead of failing halfway through.
- Files over the limit are refused up front rather than after a long wait.
Limitations, stated up front
- Formulas are exported as their last cached value, not recalculated, and the formula text itself is not included.
- Only the built-in Excel date formats plus custom formats that clearly contain date or time tokens are converted. A custom format Furtu cannot recognise leaves a serial number in the output.
- Cell styling, merged cells, column widths, conditional formatting, charts, pivot tables, defined names and macros are not carried across — CSV is a flat format and there is nowhere to put them.
- Hidden sheets are exported along with visible ones, because the workbook does not reliably record which sheet was on screen.
Frequently asked questions
Do I get every sheet?
By default you get one CSV per sheet, named after the sheet, so nothing is silently dropped. Switch the control to “The first sheet only” if you just want the active-looking one.
Why are my dates numbers?
That is how Excel stores them — a day count from 1899, with the formatting stored separately from the value. Furtu reads the number format on each cell and, when it recognises it as a date, writes a real ISO date instead. A custom number format Furtu does not recognise is left as a number rather than guessed at, which is the honest failure.
What happens to formulas?
You get the last value Excel calculated and cached, not the formula. That is usually what you want in a CSV — a number you can sum. If the file was produced by a script that wrote formulas without saving results, those cells come out empty.
Can I open the CSV in Excel without it mangling my data?
Values containing a comma, a quote or a newline are quoted, and quotes inside values are doubled, so the result round-trips. Two things are still worth knowing: Excel guesses at columns on import, and it re-derives dates from its own locale. If a column matters, import it as text and set the type yourself.
Is the workbook uploaded?
No. The spreadsheet is unzipped and read in this tab. That matters for a budget, a client list or a staff spreadsheet more than it does for a public report.