XLSX and CSV are two different ways of storing tabular data, and import systems, scripts, and databases often require specifically one or the other. Let's look at how they differ and how to convert a spreadsheet from one format to the other.
How XLSX and CSV differ
XLSX is the Excel format, which stores not just cell values but also formatting, formulas, multiple sheets within one workbook, fonts, and colors. It's a "full-featured" spreadsheet with its whole structure intact.
CSV is a plain text file where cell values are separated by commas and each row of the table is a separate line of text. No formatting, formulas, or multiple sheets — just the raw data. In exchange, virtually any program understands CSV: databases, Python scripts, online store import systems, and CRMs.
When you need XLSX to CSV
If a spreadsheet needs to be loaded into a system that only accepts plain text — a CRM, a database, a data-processing script — use the XLSX to CSV converter. It's important to understand that formulas, cell formatting, and every sheet except the active one are lost in the process: CSV simply can't store them, only the computed values survive.
When you need CSV to XLSX
If the data arrived as a CSV export (from a database, a CRM, or another program) and it's more convenient to work with it as a regular spreadsheet — sorting, filtering, formatting — use the CSV to XLSX converter. The result opens in Excel, LibreOffice Calc, and Google Sheets, and is fully ready to edit.
How the delimiter and encoding are handled
Both converters use a comma as the value separator and UTF-8 encoding by default — standard settings that work for the vast majority of CSV files, including ones containing Cyrillic text.
Bottom line
XLSX is for working with a full-featured spreadsheet: formulas, formatting, multiple sheets. CSV is a universal data-exchange format between different systems, but without formatting. Converting a spreadsheet between the two formats takes one step, with no manual data transfer.