ID-like Number Redaction Regex

Security

Regular expression

/\b\d{6,20}\b/

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

123456789012

Should not match

123
not matching sample
123456789012 invalid
123123456789012

Test cases

Input	Expected	Why it matters
`123456789012`	Match	Representative valid input for this pattern.
`123`	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.
`123456789012 invalid`	No match	Common invalid or boundary input.
`123123456789012`	No match	Common invalid or boundary input.

JavaScript

const re = /\b\d{6,20}\b/;
re.test(input);

Python

import re
bool(re.search(r"\b\d{6,20}\b", text))

PHP

$ok = preg_match('/\b\d{6,20}\b/', $value) === 1;

Java

Pattern pattern = Pattern.compile("\\b\\d{6,20}\\b");
pattern.matcher(value).find();

Go

re := regexp.MustCompile(`\b\d{6,20}\b`)
ok := re.MatchString(value)

Notes and production use

ID-like Number Redaction 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.

ID-like Number Redaction