.csv · text/csv
What is a .csv file?
Comma-Separated Values
About the format
A .csv file is tabular data as plain text: one row per line, columns separated by commas (or, in much of Europe where the comma is the decimal separator, by semicolons — the first thing to check when a CSV opens as one giant column). It's the universal export/import format for spreadsheets, databases, banks and every reporting tool. Excel opens CSV on double-click but is also the source of most CSV grief: it silently reformats things (long numbers to scientific notation, anything date-like to dates, leading zeros stripped from phone numbers and postcodes) and saves back with your locale's delimiter. For inspection without side effects, a text editor shows the truth. One genuine security note: spreadsheet formula injection — a cell starting with =, +, - or @ in a CSV from an untrusted source can execute as a formula when opened in Excel, an old trick for exfiltration prompts. Excel warns about this; the caution costs nothing.
How to open a .csv file
Windows
- Excel (convenient, but reformats)
- Notepad (shows the real content)
- Power Query (controlled import)
macOS
- Numbers, Excel, any editor
Linux
- LibreOffice Calc, any editor
Is a .csv file dangerous?
Mostly no. From untrusted sources, watch the formula-injection quirk when opening in a spreadsheet app.
Related file types
Not sure what a file is? Check its bytes.
File names lie; magic numbers don't. Drop any file into the identifier — nothing is uploaded.
Identify a file →