The XLS file format stores data in the XLS format. Converting to NUMBERS produces a spreadsheet file that stores data in the NUMBERS format. This conversion changes the file's encoding, compression method, and supported feature set. Cell values and structure are preserved; formulas are evaluated to their computed values in plain-text target formats. This makes NUMBERS the practical choice when the destination system requires it or when the target format offers better compatibility or compression. 1converter runs this conversion on the server: your file is uploaded encrypted over HTTPS, converted using trusted open-source libraries, and the output is held for 24 hours before automatic deletion.