I have a spreadsheet file (such as XLS, XLSX, or CSV) that contains multiple contact details, and I need to convert it into VCF (vCard) format. The problem is that Microsoft Excel is not installed on my system, and I do not want to install it just for this task. Is there any reliable way to convert a spreadsheet to VCF without installing Excel? What tools or methods can be used to ensure accurate conversion while keeping all contact fields (name, phone number, email, address, etc.) intact?