What does the French Phone Number regex match?

Matches a French metropolitan phone number in domestic or international format.

Is the French Phone Number regex ReDoS-safe?

Yes. Manually audited and tested against ReDoS attack strings. Anchors and possessive-style constraints prevent runaway backtracking paths.

How do I use this regex in javascript?

// No imports required — RegExp is built into JavaScript const regex = /^(?:\+33[\s.-]?|0)(1|[2-9])[\s.-]?([0-9]{2})[\s.-]?([0-9]{2})[\s.-]?([0-9]{2})[\s.-]?([0-9]{2})$/; const isValid = regex.test(input);

Localization/Phone Numbers

Verified Safe

French Phone Number Regex for JavaScript

/^(?:\+33[\s.-]?|0)(1|[2-9])[\s.-]?([0-9]{2})[\s.-]?([0-9]{2})[\s.-]?([0-9]{2})[\s.-]?([0-9]{2})$/

What this pattern does

This page provides a comprehensive, battle-tested regular expression for matching french phone number, ported and verified for JavaScript. A rigorously tested regex reduces debugging time and protects your application from edge-case failures. The snippet below is ready to drop into your JavaScript project — whether you're validating in an Express middleware, a Next.js API route, or a client-side form.

Javascript Implementation

Javascript

// French Phone Number
// ReDoS-safe | RegexVault — Localization > Phone Numbers

const frenchPhoneNumberRegex = /^(?:\+33[\s.-]?|0)(1|[2-9])[\s.-]?([0-9]{2})[\s.-]?([0-9]{2})[\s.-]?([0-9]{2})[\s.-]?([0-9]{2})$/;

function validateFrenchPhoneNumber(input: string): boolean {
  return frenchPhoneNumberRegex.test(input);
}

// Example
console.log(validateFrenchPhoneNumber("+33 1 42 34 56 78")); // true

Test Cases

Matches (Valid)	Rejects (Invalid)
`+33 1 42 34 56 78`	`+33 0 42 34 56 78`
`01 42 34 56 78`	`42 34 56 78`
`+33612345678`	`+44 1 42 34 56 78`
`06 12 34 56 78`	`01 42 34 567`
`09 12 34 56 78`	—

When to use this pattern

This pattern is drawn from the Localization > Phone Numbers category and carries a ReDoS-safe certification. That matters for JavaScript developers because especially critical in long-running Node.js event loops where a ReDoS vulnerability can block the entire process. RegexVault audits patterns against known backtracking attack vectors, ensuring you have the necessary context before using this regex in a high-stakes production environment.

Common Pitfalls

French overseas territories (DOM-TOM) use different prefixes — Réunion is +262, Guadeloupe/Martinique/French Guiana are +596/+594, New Caledonia is +687. These are not matched by this pattern.

Technical Notes

French numbers are always 10 digits in domestic format (excluding leading 0). Zones: 01 (Paris), 02 (northwest), 03 (northeast), 04 (southeast), 05 (southwest), 06-07 (mobile), 08 (special), 09 (VoIP). +33 replaces the leading 0.

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