Why opening a CSV in Excel damages it
Double-clicking a CSV does not open the file; it imports it, and the import guesses the type of every cell. That guessing is what destroys data. A product code of 00123 loses its zeros and becomes the number 123. A reference like 1-2 becomes the 2nd of January. A fifteen-digit barcode becomes 1.23457E+14 and the last digits are gone for good. None of it is reported; the file simply opens, looking fine.
What this does differently
Converting here writes a real .xlsx where every cell that is not unambiguously numeric is stored as text. The spreadsheet opens with the values exactly as they were in the file, because there is no import step left to guess. Numbers that genuinely are numbers — a price, a quantity — still arrive as numbers, so sums work.
Several files, several results
Dropping more than one CSV gives you one converted workbook per file. That is what a converter does: one file in, one file out. Take them in a zip, which is one download, or as separate files, which is easier when each one goes to a different person. Nothing here is ever merged — if you need twelve exports stacked into a single table, that is the spreadsheet merger, a separate tool in the same menu.
Encoding and delimiter
The same detection used across the site applies: a file that is not valid UTF-8 is read as Windows-1252, which is what most ERP exports produce, so accents survive. The delimiter is detected from the content, which matters because a Brazilian or European export uses semicolons to avoid splitting decimal commas.
Why it runs in your browser
A CSV export is usually the complete contents of something — every customer, every order. Sending that to a conversion service means handing over the whole dataset for a format change your own machine can do instantly.
Dates stay as written
A date in a CSV is nothing but text, and what it means depends on a convention the file does not record: 01/02/2026 is the 1st of February in most of the world and the 2nd of January in the United States. Rather than guess, the converter leaves date-looking text as text, so what opens is exactly what the file said. If you need real dates in the spreadsheet, select the column in Excel and convert it there with the format you know is right — a decision you can make correctly and the file cannot make for you.
Want to go deeper? Read our guide: Why a CSV file opens wrong in Excel, and how to fix it