CSV Row Regex

Extraction

Regular expression

/^(?:"(?:[^"]|"")*"|[^,\r\n]*)(?:,(?:"(?:[^"]|"")*"|[^,\r\n]*))*$/

Pattern breakdown

Part	Meaning
`Anchor or context`	Use anchors when you need whole-string validation.
`Main token`	The core token sequence describes the accepted text shape.
`Character class`	Character classes limit which characters are valid.
`Quantifier`	Quantifiers control how many characters or groups are accepted.
`Flags`	Use language-specific flags such as i, m, or u only when needed.

Should match

"Ava",42,"NY"

Should not match

"unclosed,cell
not matching sample
"Ava",42,"NY" invalid
"unclosed,cell"Ava",42,"NY"

Test cases

Input	Expected	Why it matters
`"Ava",42,"NY"`	Match	Representative valid input for this pattern.
`"unclosed,cell`	No match	Common invalid or boundary input.
`(empty string)`	No match	Common invalid or boundary input.
`not matching sample`	No match	Common invalid or boundary input.
`"Ava",42,"NY" invalid`	No match	Common invalid or boundary input.
`"unclosed,cell"Ava",42,"NY"`	No match	Common invalid or boundary input.

JavaScript

const re = /^(?:"(?:[^"]|"")*"|[^,\r\n]*)(?:,(?:"(?:[^"]|"")*"|[^,\r\n]*))*$/;
re.test(input);

Python

import re
bool(re.search(r"^(?:\"(?:[^\"]|\"\")*\"|[^,\r\n]*)(?:,(?:\"(?:[^\"]|\"\")*\"|[^,\r\n]*))*$", text))

PHP

$ok = preg_match('/^(?:"(?:[^"]|"")*"|[^,\r\n]*)(?:,(?:"(?:[^"]|"")*"|[^,\r\n]*))*$/', $value) === 1;

Java

Pattern pattern = Pattern.compile("^(?:\"(?:[^\"]|\"\")*\"|[^,\\r\\n]*)(?:,(?:\"(?:[^\"]|\"\")*\"|[^,\\r\\n]*))*$");
pattern.matcher(value).find();

Go

re := regexp.MustCompile(`^(?:"(?:[^"]|"")*"|[^,\r\n]*)(?:,(?:"(?:[^"]|"")*"|[^,\r\n]*))*$`)
ok := re.MatchString(value)

Notes and production use

CSV Row regex is useful as a practical starting point. Test it against your real input, avoid using it as the only security control, and prefer a parser when the format has complex grammar.

Performance tip: avoid running complex regular expressions repeatedly on very large untrusted strings without limits. Prefer anchored validation patterns, cap input length before matching, and use a parser when the target format has nested grammar.

CSV Row