Excel Converter (XLSX/CSV/JSON)

How it works

Drop in an Excel workbook (.xlsx or .xls), a CSV, or a JSON file, and the tool reads the table right in your browser and shows a live preview. Pick an output format — CSV, JSON, or XLSX — and download the converted result. When you export to CSV you can choose the delimiter (comma, semicolon for European CSV, or tab for TSV); when you export to JSON you decide whether the first row is a header, giving you either an array of objects keyed by column names or a plain array of arrays. Going the other way, a CSV or JSON array becomes a proper .xlsx you can open in Excel, Google Sheets, or Numbers. Everything runs through SheetJS on your device, with no software to install and no account to create.

When to use it

Reach for it whenever a spreadsheet is in the wrong shape for the next step. Export a sheet as .xlsx and turn it into JSON to seed a database, mock an API, or drop straight into code, or into CSV to feed a script or import tool. Go the opposite way to take a JSON response from an API or a log file and hand a colleague a clean Excel file they can open and filter without any technical setup. It also saves you from writing a throwaway parser or spinning up a spreadsheet app for a one-off reshape, and lets you restructure data on a phone or a locked-down machine where Excel isn't installed. Because it reads .xls, .xlsx, .csv, and .json alike, one page covers most everyday table conversions.

Sheets and large files

A workbook with several tabs is handled sheet by sheet: choose which sheet to convert and check it in the preview first, since columns and header positions often differ between them. Large files — tens of thousands of rows — are processed entirely in memory inside the browser tab, so on a modest device a big conversion can run slowly or make the tab appear to freeze for a moment; trimming to just the sheets and ranges you need, or running it on a desktop with more memory, keeps things quick. Bear in mind that this is a value-focused converter: formulas are written out as their calculated results, and cell styling, charts, merged cells, and comments do not carry across, because CSV and JSON store data rather than presentation.

Privacy and what to keep

Every conversion happens inside your browser, and the file you open is never uploaded, logged, or stored on a server — so internal sales sheets, customer lists, and accounting data can be reshaped without the contents ever leaving your device, and the page keeps working offline once it has loaded. Because changing format can drop anything that isn't a plain value, always keep a backup of the original .xlsx. Treat the output as a reference and check important values against the source: long numbers, leading zeros, account or phone numbers, dates, and decimals can shift format or turn into scientific notation depending on how a target program reads them. A quick visual pass after converting catches these before the data is used somewhere strict.

Frequently asked questions