Does my Excel file get uploaded to a server?

No. The whole conversion runs inside your browser using a client-side spreadsheet parser. Your file never leaves your device, which makes it safe for confidential financial, HR or customer data.

Which spreadsheet formats can I convert?

The tool reads modern Excel workbooks (.xlsx, .xlsm, .xlsb), the legacy binary .xls format, and OpenDocument spreadsheets (.ods). Each is converted to CSV or JSON the same way.

How are multiple sheets handled?

Every worksheet in the workbook becomes a tab. You can export the selected sheet on its own, or use the "All sheets to JSON" button to get one JSON object keyed by sheet name with each sheet as an array of rows.

What does the "Type numbers and booleans in JSON" option do?

When enabled, cells that look like numbers become JSON numbers and true/false become JSON booleans, instead of every value being a string. Values with leading zeros (like phone numbers) are kept as strings so they are not mangled.

Can I change the CSV delimiter?

Yes. You can output comma, semicolon, tab or pipe-separated values. Semicolon is handy for European locales where the comma is a decimal separator, and tab gives you a clean TSV.

How does it handle commas, quotes and line breaks inside cells?

CSV output follows the RFC 4180 convention — any field containing the delimiter, a double quote or a newline is wrapped in double quotes, and embedded quotes are doubled, so the file re-imports cleanly into Excel, Google Sheets or a database.

Excel (XLSX) to CSV & JSON Converter

A fast, private Excel to CSV and JSON converter that turns any spreadsheet into clean, import-ready data without installing software or trusting an upload server. Drop an .xlsx, .xls, .xlsb, .xlsm or .ods file onto the page, pick the sheet you want, glance at a live preview to make sure the columns line up, then download well-formed CSV or structured JSON. It is built for analysts, developers and ops people who constantly receive spreadsheets from finance, suppliers or exports and need them in a machine-friendly shape — to load into a database, feed an API, diff in Git, or hand to a script. Because the entire conversion happens inside your browser, the workbook never touches a network, so it is genuinely safe for confidential financial models, HR records, customer lists and anything else you would not want sitting on someone else’s server.

How it works

When you select a file, the tool reads its raw bytes and parses the workbook with a client-side spreadsheet engine. Each worksheet is flattened into a rectangular grid: rows are padded to the widest column so the preview and exports stay aligned, dates are normalised to ISO timestamps, and you decide whether the first row should be treated as a header. With header mode on, that first row becomes your CSV header and the keys of every JSON object; duplicate or blank header names are made unique automatically (for example name, name_1). CSV export applies proper RFC 4180 quoting so values containing commas, quotes or line breaks survive a round trip back into Excel or a database. JSON export produces an array of objects — optionally type-coercing numbers and booleans while protecting leading-zero strings like phone numbers and account codes. Multi-sheet workbooks expose every tab, and a single click exports them all into one keyed JSON document.

Example

Suppose finance sends you Q3-actuals.xlsx with a Revenue sheet whose first row reads region, units, net. Load it, keep “First row is the header” ticked, and the JSON export gives you:

[
  { "region": "EMEA", "units": 1200, "net": 84500.5 },
  { "region": "APAC", "units": 980, "net": 61200 }
]

Switch the delimiter to semicolon and the CSV export becomes region;units;net — ideal for a European locale. Need everything at once? “All sheets to JSON” returns { "Revenue": [...], "Costs": [...] } so you can hand the whole workbook to a script in a single file. Every row is included in the download even though the on-screen preview is capped for speed, and nothing is ever uploaded.