CSV to Excel
Convert CSV, TSV or JSON to a real .xlsx workbook.
Turn Raw Data Into a Proper Spreadsheet
Opening a CSV in Excel is a gamble: postcodes lose their leading zeros, long IDs turn into 1.23E+15, dates get swapped depending on your region, and accents break. Converting to a real .xlsx avoids all of it. Paste the data or drop a CSV, TSV or JSON file, check the preview, and download a workbook that opens the same way everywhere.
Numbers and ISO dates become real values you can sum and sort, while codes such as 00412 or long account numbers stay as text. The header row is bold, frozen and filterable, and columns are sized to their contents. JSON arrays of records are flattened, with nested fields as dotted column names.
Key features
- CSV, TSV, semicolon and pipe files, with the separator detected.
- JSON arrays of objects or rows, nested fields flattened.
- Smart types: numbers and ISO dates as values, leading zeros kept as text.
- Bold, frozen, filterable header and fitted column widths.
- Real .xlsx for Excel, Google Sheets, Numbers and LibreOffice.
This tool does its work inside your browser using native Web APIs. The files and text you give it are processed on your device and are not uploaded to our servers.
How to use: CSV to Excel
- Add the data
Paste CSV or JSON into the box, or drop a .csv, .tsv or .json file. - Check the preview
Confirm the separator and header; the size is shown. - Name the sheet
Optionally rename the sheet and choose the options. - Download
Press Download .xlsx.
Technical specifications
| Processing location | Entirely in your browser — no server round trip |
|---|---|
| Data uploaded | None. Files and text never leave your device |
| Price | Free — no account, no trial, no usage cap |
| Category | Converters |
| Works offline | Yes, once the page has loaded |
| Browser support | Chrome 90+, Edge 90+, Firefox 90+, Safari 15+ |
| Interface languages | English, 中文, हिन्दी, Español, العربية |
Frequently asked questions
Why convert instead of opening the CSV in Excel?
Excel guesses types when it opens a CSV and often guesses wrong — dropping leading zeros and mangling long numbers and dates. An .xlsx stores each cell’s type explicitly.
How are dates handled?
ISO dates such as 2026-03-02 or 2026-03-02T10:30 become real Excel dates. Other formats stay as text, because 03/02 means different days in different countries.
What JSON shapes work?
An array of objects (one row each), an array of arrays, or an object containing such an array. Nested objects become dotted column names.
Is there a size limit?
Excel’s own: 1,048,576 rows. Practically, a few hundred thousand rows convert comfortably in a browser.