GoAddress
GoAddress is a UK postcode and address lookup API designed to deliver fast, accurate address data in seconds. It allows developers to search by postcode or full and partial address text using simple REST endpoints. The API returns clean, structured address data that is ready for use in forms, databases, and applications. GoAddress is built for production use cases such as checkout flows, customer onboarding, and internal systems. Address data is refreshed daily to ensure accuracy and reliability. Secure API key authentication and high availability make it suitable for business-critical applications. Trusted by thousands of developers, GoAddress offers a quick setup with no credit card required for the free tier.
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Postcoder
Postcoder is an API from Allies Computing that gives developers a single endpoint for verifying and validating customer contact data at the point of entry. Used across sectors from healthcare to retail, it's built to drop into checkout, onboarding, and account creation flows with minimal friction.
What's included:
Address lookup – Postcode, partial address, or coordinate-based search across Royal Mail PAF, Ordnance Survey AddressBase, and 249 countries worldwide.
Bank validation – Real-time sort code and account number verification, with branch data and direct debit eligibility returned in the response.
Email validation – Domain and formatting checks with disposable address detection.
Mobile validation – Live network status checks across 200+ countries.
OTP verification – SMS-based one-time password delivery.
Clear documentation, multi-language sample code, and a straightforward REST structure mean integration is quick. 30 day free trial with no credit card required.
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Postcodes.io
Postcodes.io is an open source postcode lookup API and geocoder for the United Kingdom that lets developers search, validate, and geolocate UK postcodes while retrieving detailed administrative and geographic information. The API can look up complete postcode records, reverse geocode latitude and longitude coordinates to nearby postcodes, search by partial postcode strings, find nearest postcodes to a location, and query outward codes and places. Responses can include coordinates, regions, administrative districts, counties, wards, parishes, parliamentary constituencies, statistical areas, health geographies, rural-urban classifications, and other associated codes and attributes. Bulk reverse geocoding allows large sets of coordinates to be converted into their nearest postcode areas, while autocomplete and validation methods simplify postcode entry and verification workflows.
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Web APIs by Melissa
4.8 out of 5 stars
(4 Ratings)
Melissa’s Web APIs provide a comprehensive solution for global data verification, cleansing, and enrichment to maintain reliable data. Verify, standardize and cleanse global identities, addresses, phones & emails, powered by AI-driven reference data. Our flexible APIs are designed for modern interfaces, including REST, JSON, and XML are easily accessible through our Developer Portal, where you can build, test, and explore integrations.
Enhance your data with geographic, demographic, and firmographic insights, along with U.S. property data for advanced enrichment. Melissa supports seamless integration with popular platforms such as Salesforce, Shopify, and more, making data management and governance simple and efficient. Whether you’re focused on data management, data validation, or leveraging our APIs into your website or mobile applications, Melissa helps you unlock the full potential of your data.
Get started with 1,000 complimentary credits! All you need is a Melissa account
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