Is this tool really offline?

Yes. All processing happens locally in your browser using JavaScript. Your files never leave your device.

Yes, completely free with no registration or account required.

Absolutely. No files or data are uploaded to any server. Everything stays on your device.

JavaScript is required to use these tools. Please enable JavaScript in your browser settings to convert files.

Zero-Server Storage · 100% Private Your files are processed entirely in your browser. Nothing is uploaded, stored, or seen by anyone — safe for confidential & GDPR/HIPAA-sensitive documents.

XLS to XLSX Converter - Free & Offline (No Upload)

Convert legacy XLS spreadsheets to modern XLSX completely offline in your browser. No upload, 100% private.

No Upload 100% Private Free

You might also need:

CSV to Excel Excel to CSV CSV to JSON JSON to CSV DOCX to PDF

Drop your XLS file here

or click to select a XLS file

Frequently Asked Questions

Is my data private?

Yes. All processing happens in your browser with no data sent to any server.

Is there a size limit?

No limit. Processing is limited only by your browser's memory.

Related Data Tools

CSV to Excel Excel to CSV CSV to JSON JSON to CSV DOCX to PDF