Spreadsheet Cleanup & Reconciliation

Clean a messy spreadsheet, or compare two exports and see exactly what changed — without writing a single formula. Your files are read in this browser and never leave your device.

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Processed on this device · nothing is uploaded · nothing is saved
What that means

Every file you choose is read by code running in this browser tab. There is no upload, no server processing and no analytics on this address. Nothing is written to storage unless you download a file yourself. It is not encrypted, because it never travels anywhere — close the tab and it is gone.

  1. Import
  2. Set up
  3. Review
  4. Download
Step one

What would you like to do?

Step two

Choose your files

CSV, TSV or XLSX. Your original file is never changed — everything here is a preview until you download.

The sample is invented data, not an analysis of anything of yours.

What this tool does, and what it does not

How your data is treated
  • Nothing is guessed. A date like 03/04/2026 is not converted until you say whether it is day-first or month-first. A number is not read out of text that only partly looks like one.
  • Identifiers stay as they are. 00123 keeps its zeros, a long account number keeps every digit, and a phone number is never treated as arithmetic. Values only become numbers when you ask for that.
  • Money is compared exactly. Differences are worked out in decimal arithmetic, so a comparison never invents a penny that is not there.
  • Formulas are never run. In a workbook, the result last saved by your spreadsheet program is used. Where a formula has no saved result, that cell is flagged rather than shown as blank.
  • Your original file is never modified. Every step is applied to a copy in memory, and turning a step off puts the data back.
Limits, honestly
  • Files are held in memory. About 100,000 rows is comfortable on a typical laptop; much larger files may make the tab slow or run out of memory, and how much you can load depends on the device.
  • Processing happens on the page itself, so a very large file will make the page pause while it works rather than showing a progress bar that means nothing.
  • Exported workbooks are new, values-only files: the data and sheet names, not the colours, column widths, charts or formulas of the original.
  • Password-protected workbooks, .xls, .xlsm and .ods files are refused rather than half-read. Open them in your spreadsheet program and save as .xlsx or CSV.
  • Nothing is saved between visits. There is no draft, no history and no account — closing the tab discards everything.

Need the reverse — turning one table into many files, or reading a PDF table? See Developer & Data tools.