Turn XLS files into JSON in a couple of clicks. XLS is Excel's pre-2007 binary workbook; JSON is the default data interchange format for APIs. Content is pulled out of the source container rather than re-authored.
Drop your files here
XLS files (.xls) · up to 100 MB each
or paste files from your clipboard
Ready when you are
Drop a XLS file above and FileTools360 will turn it into JSON — right here on your device, without uploading anything.
Drag them onto the drop area, choose them from your device, or paste them from your clipboard. You can queue several at once. Nothing is sent anywhere — the file stays on this device.
The defaults suit most people. Open Advanced to control delimiter and header handling and indentation and element names.
Press Convert. Everything happens on your own device — nothing is uploaded. Download files one by one, or grab them all as a ZIP.
Privacy, in plain words
What “uploaded” normally means. On most online converters, pressing the button copies your file across the internet onto a computer owned by that website. That copy is what the word “upload” means, and it is the part nobody explains.
What happens instead. This site does not do it. There is no server here that receives files, so your XLS file is read, converted and handed back by the browser you are using right now. It never travels — so there is no copy to store, read, leak or hand over.
Check it yourself in ten seconds
Turn off your Wi-Fi after this page has loaded, then convert a file anyway. It still works, because everything needed is already on your device.
The longer explanation of how this works, and the full detail of what is and is not stored on the privacy page.
A spreadsheet is rarely about one person. It is usually about hundreds of them, which is what turns an ordinary file into a reportable data breach. It matters more than it sounds, because of what spreadsheets usually are:
Customer and member lists
names, emails, phone numbers, addresses
Patient or client records
regulated personal data under HIPAA, GDPR and similar
Financial models and forecasts
numbers a competitor would pay for
Supplier pricing
commercially confidential by contract, usually
A file that is never sent cannot be kept, leaked, subpoenaed or used to train anything. That is a property of how this works, not a promise about how carefully it is run.
The pre-2007 Excel format is a binary structure limited to 65,536 rows and 256 columns — limits modern datasets routinely exceed.
JSON represents structured data as nested objects and arrays. It came from JavaScript but is now the default interchange format for essentially every web API.
The two formats solve different problems, which is why converting between them involves trade-offs rather than a straight upgrade.
| Property | Source | Target |
|---|---|---|
| Compression | None | None |
| Introduced | 1987 | 2001 |
| Browser support | Still opens in Excel and LibreOffice. | Every modern language and tool. |
People make this switch when they run into the limits of XLS: anything else — XLSX is better in every respect. JSON is the better fit when APIs, configuration and any data with structure beyond a flat table.
A JSON file holds one part of what an XLS file contains. That part is taken out as it is, and everything else in the container is left behind rather than converted. Nothing is re-encoded in the process, so the extracted content keeps whatever quality it already had.
On every sample measured, the JSON came out smaller — 2.4× smaller at worst and 4.4× smaller at best.
| Sample | XLS in | JSON out | Change |
|---|---|---|---|
| A plain tableTen rows of flat records — the shape almost every spreadsheet export actually has. | 5.0 KB | 1.3 KB | −75% |
| Many columnsForty columns across three rows. Column-heavy data is where per-cell overhead shows up. | 7.5 KB | 3.1 KB | −59% |
| Nested recordsObjects inside objects. This is the shape that cannot survive a flat format intact, and the one that triggers a warning. | 4.5 KB | 1.1 KB | −76% |
| Commas and quotation marksText fields containing the delimiter and the quote character — where an escaping bug would show. | 5.5 KB | 1.2 KB | −78% |
Produced by this site's own converter. The same code that runs in your browser, at the same default settings, so these are the bytes you would download.
Samples are generated from a fixed seed rather than taken from real photographs or documents, so the corpus is reproducible and carries no licensing question — and so the numbers predict the shape of your result rather than its exact size. Measured 2026-10-01. The method, and the command that regenerates every figure on this page, are on the how it works page.
Source
Excel's pre-2007 binary workbook.
Target
The default data interchange format for APIs.
Rows become objects keyed by the header row. Switch the header toggle off to get arrays instead.
Good to know
Runs entirely in your browser
527 converters and tools65 file formatsnothing ever uploaded.