Free Phone Number Validation & Lookup API NumVerify offers a powerful and simple API for international and national phone number validation. Requests are made using a simple URL structure, and results are delivered in handy JSON format. Provide any phone number in any format, and our API will return an easy-to-integrate response containing validation results, the requested phone number in its national and international format, country, location, carrier and line type information.Validating phone numbers and obtaining this type of information at the time a new user signs up, developers and businesses are able to take informed steps towards the right means of communication with the particular customer, reduce undelivered messages and fight fraudulent and fake users at the same time.