E.164 phone number formatter
Almost every API that touches phone numbers - Twilio, Stripe, WhatsApp, most CRMs - expects E.164: a plus, the country code, and the national number with nothing else. This converts messy input into that shape.
Free, no signup, no daily limit. We do not store what you check here.
What E.164 requires
A leading plus, then the country calling code, then the national significant number. No spaces, no dashes, no brackets, and no leading zero from the national trunk prefix. Maximum fifteen digits after the plus. Stripping that trunk zero is where hand-rolled conversion usually goes wrong: the UK number 020 7183 8750 becomes +442071838750, not +4402071838750.
Why storing E.164 matters
It is the only format that is unambiguous across countries, which makes it the only safe key for deduplication. A database holding the same subscriber as "020 7183 8750", "+44 20 7183 8750" and "00442071838750" has three records and no way to know it.
Questions
Do I need to know the country in advance?
Not if the number already carries a country code. Without one the number is ambiguous and cannot be converted reliably.
Why was my number rejected?
Usually because it is missing a country code, or because it is not valid in the numbering plan it claims. The result explains which.
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When you need more than a free tool
This page answers what can be determined offline and from public DNS. The API adds live carrier and mailbox verification, a calibrated confidence score, and the full evidence trail behind every verdict.
Credits never expire. Inconclusive verdicts are never billed. Cancel in one call. See pricing or read the docs.