Convert XLSX to XLS Spreadsheet With Free XLSX to XLS Converter
Without using additional program like Microsoft Office Compatibility Pack, you cannot open XLSX files in previous Microsoft Excel versions like Microsoft Excel 2003 or Microsoft Excel XP. This pack also enables you to convert XLSX to XLS spreadsheet. There are alternatives if you don’t want to install it, though. Open XLSX online or convert it to XLS using other XLSX converters.
Instead of installing any software, you can use an online converter. There are quite many options if you want to do it online, and one of the alternatives is Convert Files. It allows you to upload file from either an URL or from your computer. However, you must leave your email address since the link of the conversion result will be sent to it once the conversion is completed. If you reluctant to leave your original email address, you can always use a disposable or temporary email address. The conversion is free.