.csv — Comma-Separated Values
Data text/csv
What a .csv file is
Plain text where each line is a row and commas separate the fields. No types, no formulas, no formatting — which is exactly why it is universal.
How to open it
Any spreadsheet or text editor. For a clean import, use Excel's import wizard rather than double-clicking the file.
Worth knowing
Excel mangles leading zeros and long numbers on open, and some locales expect semicolons instead of commas. Convert CSV to JSON if you are feeding a program rather than a person.
How to identify a .csv file
A file's extension is only its name — renaming a.png to a.csv changes nothing inside. What software actually reads is the magic number, the first few bytes of the file.
| Signature | none |
| MIME type | text/csv |
| Category | Data |
Plain text with no signature, which is why CSV detection is guesswork.
# what is this file really?
file mystery.csv
# look at the first bytes yourself
xxd mystery.csv | head -2
head -c 16 mystery.csv | xxd
# Windows PowerShell
Get-Content mystery.csv -AsByteStream -TotalCount 16 | Format-HexFrequently asked questions
What is a .csv file?
Plain text where each line is a row and commas separate the fields. No types, no formulas, no formatting — which is exactly why it is universal.
How do I open a .csv file?
Any spreadsheet or text editor. For a clean import, use Excel's import wizard rather than double-clicking the file.
Is .csv safe to open?
Yes. A .csv file is data, not code — opening one cannot execute anything by itself.
Can I change a file's extension to convert it?
No. Renaming changes the label, not the bytes. The one place it appears to work is between formats that genuinely share a container — renaming .docx to .zip works because a DOCX is a ZIP. Everything else needs a real converter.
Other data formats
- .json — JavaScript Object Notation
- .yaml — YAML Ain't Markup Language
- .sql — SQL Script
- .parquet — Apache Parquet