Why phone number regex validation is always wrong — and what to use instead

A technical deep-dive on DEV Community argues that regex-based phone number validation is fundamentally flawed, not merely imperfect, because valid number formats vary by country, prefix type, and frequently changing carrier rules. A common tutorial regex was tested against six real-world numbers and produced four false positives and two false negatives. The author points to Google's FALSEHOODS.md, which lists 27 false assumptions developers make about phone numbers, including the misconception that phone numbers are purely numeric. The recommended solution is to use libphonenumber-js, a JavaScript port of Google's authoritative phone metadata library, which parses and validates numbers using real-world data. The article also distinguishes between E.164 storage format and display formatting, stressing that only the standardised E.164 form should ever be saved to a database.