Spreadsheet Converter
Free online spreadsheet converter. Convert Excel (XLSX/XLS), CSV, TSV, JSON and ODS between each other — Excel to CSV, Excel to JSON, CSV to Excel, JSON to Excel and more. Everything runs in your browser, so your data is never uploaded.
Drop a spreadsheet or data file
or click to choose · XLSX, XLS, CSV, TSV, JSON, ODS — converted in your browser
How to use the Spreadsheet Converter
- 1Drag your file onto the drop zone or click Upload and select an XLSX, XLS, CSV, TSV, JSON, or ODS file from your device.
- 2Wait a moment while the tool parses the file locally in your browser and shows a preview of the detected rows and columns.
- 3If your source has multiple sheets (XLSX/ODS), pick which sheet to convert from the sheet selector.
- 4Choose the target format from the output dropdown (for example CSV, JSON, or XLSX) and set any options such as delimiter or whether the first row is a header.
- 5Click Convert to generate the output, then review the on-screen result to confirm columns and values look correct.
- 6Click Download to save the converted file, or Copy to grab the text output (handy for CSV, TSV, and JSON) straight to your clipboard.
About the Spreadsheet Converter
Spreadsheet Converter is a free online tool that converts tabular data between the formats people actually juggle every day: Excel (XLSX and older XLS), CSV, TSV, JSON, and OpenDocument Spreadsheet (ODS). What makes it different from most "converters" is where the work happens. Everything runs entirely inside your browser using JavaScript parsing libraries, so when you drop in a file, the bytes are read locally by your own device and never leave it. Nothing is uploaded to a server, which matters when the spreadsheet holds customer emails, payroll figures, or unreleased financials. Technically, the tool reads your source file into an in-memory table of rows and cells, then serializes that table into whatever target format you pick, handling the fiddly parts: quoting fields that contain commas, escaping quotes and line breaks in CSV, choosing tab delimiters for TSV, and turning each row into a keyed object when you export to JSON. Real-world uses are everywhere. A developer needs a clean JSON array from a client's XLSX to seed a database. A marketer exports a CSV from a CRM but the analytics tool only ingests TSV. An academic on LibreOffice has an ODS file a collaborator can only open as XLSX. A finance team wants a CSV snapshot of one Excel tab without touching the workbook. Anyone who moves data between tools benefits: analysts, engineers, students, and small business owners who do not want to install desktop software or trust a random upload site. A practical tip: when converting to JSON, make sure your first row contains clean, unique column headers, because those become the object keys. For CSV, watch out for numbers with leading zeros (like ZIP codes) that spreadsheet apps strip on reopen. Because processing is local, large files are limited mainly by your device's memory rather than an upload cap, and there is no queue, account, or watermark. It matters because format friction wastes time and copying sensitive data through a stranger's server is an avoidable risk.
Frequently asked questions
When I convert to JSON, how are rows and columns turned into objects?
The first row is treated as the header, and each following row becomes one JSON object whose keys are those header names and whose values are the cells in that row. The whole file becomes an array of these objects. Make sure your header row has unique, non-empty names, since duplicate or blank headers can overwrite or drop keys.
Does converting an XLSX to CSV keep my formulas and formatting?
No, and that is expected. CSV, TSV, and JSON are plain-text data formats with no concept of formulas, cell colors, fonts, or multiple sheets. The converter exports the calculated values, not the formulas behind them. If you need formatting or multiple tabs preserved, keep the file as XLSX or ODS.
My CSV has commas inside some cells. Will that break the conversion?
No. When writing CSV, any field containing a comma, a double quote, or a line break is automatically wrapped in double quotes, and internal quotes are doubled, following the standard CSV escaping rules. This keeps columns aligned so the file reopens correctly in Excel, Google Sheets, or a parser.
Is there a file size limit?
There is no fixed upload limit because nothing is uploaded, the file is processed in your browser's memory. The practical ceiling is your device's available RAM and the browser tab. Files with tens of thousands of rows convert fine on a normal laptop; multi-hundred-megabyte spreadsheets may slow down or run out of memory.
Why did leading zeros disappear from my ZIP codes or IDs after converting?
Spreadsheet formats often store those cells as numbers, which drops leading zeros before the converter ever sees them. To keep values like 00123 intact, format the column as text in your spreadsheet app before converting, or start from a CSV where the values are already text strings.
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Frequently asked questions
Is the spreadsheet converter free and private?+
Yes. It runs entirely in your browser using SheetJS — your files and data are never uploaded, with no limits or watermarks.
Which formats can I convert?+
Excel (XLSX, XLS), CSV, TSV, JSON and ODS — in any combination. Excel→CSV, Excel→JSON, CSV→Excel, JSON→Excel, and more.
Does it keep my columns and formatting?+
Column data and the first sheet are preserved. CSV/TSV/JSON are plain data formats, so styling (colors, fonts) isn't carried over — only the values.