Convert XLSX to JSON Online Free — No Upload, Data Intact
Turn .xlsx sheets into clean, structured JSON right in your browser — headers become keys, rows become objects. No upload, no signup, no limits.
Drop .xlsx, .xlsm or .xls files here, or click to browse
Supports .xlsx / .xlsm / .xls · processed locally · never uploaded
How to Convert Excel to JSON Online
- Drop one or more .xlsx, .xlsm or .xls files — everything is processed locally and never uploaded.
- Click Convert to JSON — every sheet is read and serialized with 2-space indentation.
- Check the preview — each result lists the converted sheets and shows the first 2,000 characters of JSON.
- Download the result — a single file downloads directly; multiple files come back as a ZIP.
How the Conversion Works
Each worksheet is read in object mode: the first row supplies the keys, and every following row becomes a JSON object. Empty cells are filled with null instead of being skipped, so every entry keeps the same shape and the output is safe to iterate and merge in code.
Multi-sheet workbooks serialize as one JSON object whose keys are the sheet names in workbook order; a workbook with a single sheet returns a plain top-level array, and empty sheets export as []. Values keep their spreadsheet types — numbers stay numbers, TRUE/FALSE becomes true/false, and formulas are exported as their last calculated values.
What Each Cell Becomes in JSON
| Cell in Excel | JSON value | Notes |
|---|---|---|
| 42 / 3.14 | number | Cell formatting is not carried over — you get the raw value |
| Any text | string | Line breaks inside a cell are preserved as \n |
| TRUE / FALSE | true / false | Real boolean cells only — the text “TRUE” stays a string |
| Empty cell | null | Filled in for every column so rows stay uniform |
| Date or time | number | Excel serial number (days since the 1899 epoch), Excel’s internal storage |
| Formula | number or string | The last cached result, not the formula text |
JSON or CSV — Which Export Fits?
| JSON | CSV | |
|---|---|---|
| Structure | One object per row; multi-sheet becomes one keyed object | Flat grid, one file per sheet |
| Types | Numbers, booleans and null kept as-is | Re-typed by the spreadsheet when imported |
| Nesting | Rows are uniform objects; assemble hierarchies in code | None — strictly two-dimensional |
| Best for | APIs, scripts, configuration, databases | Spreadsheets, quick viewing, mail merge |
Privacy and Limitations
- Files never leave your device — the workbook is parsed by JavaScript in your browser.
- Styles, colors, merged cells, charts and comments are not part of the JSON data model and are not exported.
- Dates appear as Excel serial numbers; format them in your code, or export CSV instead if you need readable dates.
- Very large workbooks are limited by the memory of one browser tab, since everything is processed locally.
Frequently Asked Questions
Is this XLSX to JSON converter free?
Yes — 100% free with no sign-up, no watermark and no file limit. All conversion happens locally in your browser.
How are multiple sheets converted?
Each sheet becomes an array of row objects, and the whole workbook is returned as one JSON object keyed by sheet name in workbook order. Single-sheet files return a plain top-level array.
Why do dates show up as numbers?
Excel stores dates as serial numbers (days since the end of 1899 in the default calendar). The converter exports the stored value; format it with a date library, or export CSV if you need readable text.
What happens to formulas?
Formulas are exported as their last calculated values — the same numbers you see when opening the file. The formula text itself is not part of the JSON.
Will my file be uploaded to a server?
No. The workbook is opened and serialized by JavaScript in your browser; your file never leaves your device.
What does the converter do with empty cells?
They are filled with null so every row object has the same keys — easier and safer to iterate, merge and validate than rows with missing properties.
Can I turn JSON back into an Excel file?
Yes. Use our JSON to XLSX converter — a JSON array becomes one sheet, and an object of arrays becomes one sheet per key.
Related Tools
Need to view or edit the spreadsheet before converting?
Open the free online Excel editor