What the validator checks
Length, country prefix and number pattern against Google's libphonenumber metadata - the same rules most apps and carriers use. A "valid" verdict means the number is well-formed for its country and type; it does not probe whether the line is currently active (that requires carrier lookups, which cost money and leak your data - we don't do them).
Related tools
Have a whole list? The bulk validator checks up to 1,000 numbers at once, still entirely in your browser. Look up who a prefix belongs to with the area code lookup, browse country calling codes, or read the format guide for every country. Curious why movie numbers all start 555? See the fake phone numbers guide.
Frequently Asked Questions
How do I check if a phone number is valid?
Paste the number (with + and country code, or pick the country). The validator checks it against the official numbering plan: length, prefix and pattern, and tells you the type (mobile, landline, toll-free) plus the correctly formatted versions.
Is the number I type sent anywhere?
No. Validation runs entirely in your browser using Google's open-source libphonenumber rules. Nothing is transmitted, logged or stored, and there is no usage limit.
What is E.164 format?
E.164 is the international standard form: a plus sign, the country code, then the national number with no spaces (maximum 15 digits), e.g. +14155552671. It is the format databases, SMS gateways and telephony APIs expect.