Excel to JSON Converter: Read an XLSX Sheet as JSON or CSV

Choose an .xlsx or .xlsm file, or drag it onto the drop zone. The workbook is opened in your browser, the sheet list fills in, and the first sheet that has data is converted straight away. Pick another sheet from the list at any time. Text, numbers, booleans and dates come through as their own types, and empty cells follow the rule you choose: null, left out of the object, or an empty string.

Real spreadsheets often start with a title or a few blank rows, so you tell the tool which row holds the column names. Type 3 and rows 1 and 2 are ignored; type 0 if the sheet has no header, and keys become column_1, column_2 and so on. Duplicate or empty header cells get numeric suffixes. You can output an array of objects or an array of arrays, minified or indented, or switch to CSV with a comma, semicolon or tab delimiter and an optional Excel byte order mark on the download.

Excel stores dates as plain numbers plus a display format, and the reader recognises date formats and turns those cells into dates. You then decide how they are written: a full ISO timestamp, a date only (2024-03-05), or a date and time (2024-03-05 14:30:00). Values are read as stored, which means UTC, with no time zone conversion, so a cell showing 9:00 stays 9:00.

Numbers are read as JavaScript numbers, which are exact up to about 15 significant digits. Long identifiers such as card numbers or 18-digit ids lose their trailing digits if the cell was stored as a number, and the tool warns when it sees integers beyond 2^53. Format those cells as Text in Excel before saving to keep every digit.

The tool reads saved values only. A formula cell gives the result Excel stored when the file was last saved; nothing is recalculated, and a formula that had an error shows as empty. Hidden rows and columns are still included, merged cells keep only their top-left value, and formatting, charts, images, pivot tables and macros are ignored. Legacy .xls files and password-protected workbooks are not supported, and you get a plain explanation saying so; open them in Excel or LibreOffice and save as .xlsx first.

Files over about a megabyte are opened in a background worker, and large sheets are converted in slices, so the page stays responsive. Files up to 50 MB are accepted, but a very large workbook may still exhaust a browser tab's memory. Nothing is uploaded: the file never leaves your device.