US Address Verification
Confirm a US address is real and deliverable before you ship or save it. Standardize it, get ZIP+4, and branch on a single deliverability status. Guides and copy-paste code in every major language.
Complete Guide to Address Verification APIs in 2026
Master address verification with our comprehensive guide covering API selection, implementation, and best practices.
USPS CASS Certification: Complete Guide for 2026
Everything you need to know about CASS certification, postal discounts, and how to save up to 40% on postage.
10 Address Verification Software Tools for Developers in 2026
A developer-focused overview of the top address verification tools, covering key features, API design, and integration options.
How to Test an Address API's Accuracy
Build a truth set, damage it in controlled ways, and score five numbers: recovery, silent errors, flagged errors, empty results and refusal of fake addresses.
Do You Need CASS Certification for Address Validation?
CASS is required to claim automation and carrier route postage prices. What the postal rules say, by use case, and when a non-certified API is fine.
CASS-Certified vs Non-Certified Address Validation
One unlocks postage discounts through PS Form 3553. Both can clean your data. A side-by-side view and when each is the right tool.
Google Address Validation Alternatives: Cost at Volume
Google charges $17 per 1,000 after 5,000 free lookups. What 10K, 100K and 1M cost on Google and the alternatives, plus the caching terms that matter.
Address Validation MCP Servers for AI Agents, Compared
Eight address validation MCP servers for AI agents, updated October 28, 2026: tools, transport, sign-up, cost, registry status, and live tool calls shown.
How to Find Duplicate Customer Addresses
Find duplicate customer addresses by standardizing first. A 50-row test scores exact, normalized, fuzzy and standardized matching, with a Python script.
Address Standardization API: What Changes, With Examples
What an address standardization API changes, rule by rule from Publication 28, with three live before-and-after examples and four APIs compared.
ZIP+4 Lookup API: Get the 4-Digit Add-On by API
What the four extra ZIP+4 digits mean in the postal rules, three live responses that return them, and how seven APIs return and price ZIP+4.
Address Cleansing vs Verification vs Standardization
Four terms vendors use loosely, defined from Smarty, Loqate and Publication 28, with one address run live through a parser and a verification call.
What an Address Verification API Returns, Field by Field
One real response with every field explained, what the DPV codes Y, D, S and N mean, and the same answers under five vendors' field names.
Free Address Validation APIs: What the Free Tiers Give You
11 address verification APIs checked on one day. Three give free lookups every month; the rest are trials, one-time credits or free only with a purchase.
USPS Web Tools API Retirement: What to Move To
USPS retired Web Tools on January 25, 2026 but kept patching it. The new Addresses API is free only for USPS shipping. What changed and where to move.
Melissa Address Verification Alternatives (2026)
Melissa sells US address verification in credits. What its credit packs cost at 10K, 100K and 1M lookups, and what the alternatives charge.
How Address Verification APIs Are Priced (2026)
Public prices at 10K, 100K and 1M lookups a month, the five pricing models vendors use, and the hidden costs to check before you buy.
How to Verify US Addresses in Python
Confirm deliverability before you ship. Free API, a requests-based client, a Flask submit handler, and a clear rule for every DPV outcome.
How to Verify US Addresses in C# / ASP.NET Core
Confirm deliverability at submit. Free API, a typed HttpClient service, and an endpoint that branches on DPV - accept, warn, or block.
How to Verify US Addresses in Node.js / Express
Confirm deliverability at submit. Free API, a fetch-based client, and an Express route that branches on DPV - accept, warn, or block.
How to Verify US Addresses in PHP / Laravel
Confirm deliverability at submit. Free API, the Laravel Http client, and a controller that branches on DPV - accept, warn, or block.
How to Verify US Addresses in Java / Spring Boot
Confirm deliverability at submit. Free API, the built-in HttpClient with Jackson records, and a controller that branches on DPV.
How to Verify US Addresses in Django
Confirm deliverability at form submit. Free API, a requests-based service module, and a view that branches on DPV - accept, warn, or block.
How to Verify US Addresses in Go
Confirm deliverability at submit. Free API, a net/http client with typed structs, and an http.HandlerFunc that branches on DPV.
How to Verify US Addresses in Ruby on Rails
Confirm deliverability at submit. Free API, a Net::HTTP client, and a Rails controller action that branches on DPV - accept, warn, or block.