XLSX to JSON

How this reads your output

The workbook is read in the browser and the first sheet is emitted as an array of objects keyed by the header row. Every value is exported as a string, and that is a decision rather than a shortcut. A spreadsheet does not store dates as dates — it stores a serial number counting days from an epoch — so an export that faithfully passes through the underlying value turns a date column into numbers like 45123. That looks like real data and is silently wrong wherever it lands. Exporting the displayed string keeps what the sheet actually showed, and typing it afterwards is a decision you make with the column in front of you.

What the results mean

Strings throughout

Deliberate. Type inference on the way out is where dates become serial numbers.

Serial number

How a spreadsheet stores a date internally — days since an epoch. 45123 rather than a date.

Header row

Becomes the object keys. A sheet with a title row above the table produces keys from the title.

First sheet only

Keeps the output shape predictable rather than nesting by sheet name.

Common problems and fixes

My dates came out as strings

Deliberately. The alternative is serial numbers, which look like real data and are wrong. Parse them on the way in, where you know the column is a date.

The keys look like a title rather than column names

The header row is not the first row of the sheet — there is a title or a note above the table. Delete those rows first.

Only one sheet converted

By design. Convert each sheet separately to keep the output a flat array rather than nested by sheet.

Frequently asked questions

More in Data

• XLSX to CSVConvert a spreadsheet to CSV, one file per sheet, with what gets lost stated first.
• XLSX ViewerOpen a spreadsheet without a spreadsheet program — and without uploading it.
• JSON to XLSXTurn JSON into a workbook, with nested objects flattened rather than stringified.