Explainer1 min readUpdated June 29, 2026

What is CSV?

Short answer

CSV (comma-separated values) is a simple text format for tabular data. Each line is a row, and commas separate the values in that row. It is widely supported by spreadsheets, databases, and data tools.

A table as text

CSV stores a table as plain text. The first line is often a header naming the columns, and every following line is a record whose values line up with those columns, separated by commas.

name,role,active
Ada,author,true
Grace,engineer,true

A small CSV file

Quoting rules

A value can contain a comma, a quote, or a line break if it is wrapped in double quotes. A quote inside a quoted value is written twice. These rules, described in RFC 4180, are why a real parser is safer than splitting on commas.

name,note
Ada,"Mathematician, writer"

A quoted value with a comma

CSV has no typesEverything in CSV is text. Numbers, booleans, and dates are just strings until the program reading the file converts them.

Try it: CSV to JSONConvert CSV into JSON objects locally, or clean it up first with the CSV cleaner.Open tool

References

Questions

Do CSV files always use commas?

Comma is the default, but some files use semicolons or tabs, often because of regional spreadsheet settings. These are still loosely called CSV; the separator just differs.

Why does my CSV break in a spreadsheet?

Usually a value contains an unescaped comma or line break. Wrapping such values in double quotes, per the CSV rules, keeps the columns aligned.

Does this send my data anywhere?

No. Utilumo's developer tools parse and transform input inside the browser tab. Nothing is uploaded, stored, or logged.