Postcoder is an address lookup and customer data verification API developed by Allies Computing. Used by over 10,000 organisations worldwide, Postcoder helps businesses capture and verify customer data at the point of entry by bringing address lookup and autocomplete, bank validation, email validation, mobile validation, and OTP verification together in a single integration. With access to Royal Mail PAF, Multiple Residence data, Ordnance Survey AddressBase property records, and international addresses across 249 countries, Postcoder's address lookup and autocomplete delivers verified results instantly. Users can search by postcode, partial address, or coordinate position, with rooftop-level geocoordinates included for every result. Whether you're running an e-commerce checkout, a delivery workflow, or a customer onboarding journey, the data returned is precise and ready to use. Postcoder offers multiple features in a single API. Bank validation checks sort codes and account numbers in real time, confirms direct debit eligibility, and returns full branch details, making it well suited to lenders, subscription platforms, and businesses collecting payment mandates. Email validation assesses formatting, domain health, and risk signals such as disposable addresses, helping teams protect deliverability and maintain clean CRM records. Mobile validation checks whether a number is live and connected across more than 200 countries, reducing wasted outreach and improving contact rates. OTP verification sends one-time passwords via SMS to authenticate users at sign-up, login, or checkout, with no separate SMS provider required, making it straightforward to add an extra layer of security to any customer-facing journey. Trusted by organisations including NHS, Sky, Rightmove, and KFC, Postcoder is built for teams that take data quality seriously. A 30-day free trial, thorough documentation, and ready-to-use sample code mean developers can be up and running in minutes, no credit card needed.