Blog
Migration guides, pricing teardowns, customs and address-data explainers, and the engineering behind the API.36 posts.
Topics
How to Find the HS Code for Anything You Ship (2026)
A three-minute method for finding the right HS, HTS, or Schedule B code: five worked examples from the live US tariff schedule, plus the fields USPS validates.
- Customs
- International Shipping
Experian Address Validation (QAS) vs RevAddress — Pricing and API Compared (2026)
Experian's Address Validate API (formerly QAS Pro On Demand) is quote-only and sized for a 250-country data-quality suite. What a US team actually pays for, what it gets instead on a flat published price, and a one-afternoon migration.
- Vendor Comparison
- Address Validation
- Pricing
PostGrid vs RevAddress — Address Validation API Comparison 2026
PostGrid vs RevAddress for USPS address validation. Pricing tiers, batch support, and where validation-only stops and the full USPS shipping stack begins.
- Vendor Comparison
- Address Validation
- Pricing
Loqate vs RevAddress — Address Verification Pricing and API Compared (2026)
Loqate bills US address verification in per-lookup credits behind a sales quote. What that costs at every volume, what a flat USPS-native price looks like beside it, and how to move the US traffic in an afternoon.
- Vendor Comparison
- Address Validation
- Pricing
Melissa Address Verification Pricing in 2026: What Credits Really Cost Per US Lookup (and a Flat-Rate Alternative)
Melissa bills address verification in credits — and a single US address costs 3 of them, so the headline $0.003 rate is really ~$0.009 per lookup. Here's the real per-lookup math at every tier, and a flat-rate USPS-native migration path.
- Vendor Comparison
- Address Validation
- Pricing
Lob vs RevAddress: USPS Address Validation Without the Direct-Mail Tax
Lob vs RevAddress for US address validation. Real 2026 pricing at every tier, DPV code depth, code samples, and why USPS-shipping teams overpay on a direct-mail platform.
- Vendor Comparison
- Address Validation
- Pricing
Google Address Validation API Pricing: The Per-Request Cost (and the Flat-Rate USPS Alternative)
Google's Address Validation API costs $17 per 1,000 requests after a 5,000-call free tier — and it isn't full USPS CASS-certified. Here's the real cost at scale, the deliverability gap, and a flat-rate migration path.
- Vendor Comparison
- Address Validation
- Pricing
RevAddress Checkout Guard: Drop-In Address Risk Widget
Add real-time address validation and fraud-risk review to address forms with one script tag. WooCommerce, Shopify account forms, Magento, custom forms. Free tier.
- Checkout
- Address Validation
Smarty vs RevAddress — Address API Comparison 2026
Detailed comparison of Smarty and RevAddress for USPS address validation. Pricing, batch support, caching, and API design compared side-by-side.
- Vendor Comparison
- Address Validation
- Pricing
Fix Magento USPS AC-15210: v3 REST Replacement
Magento's built-in USPS module broke when Web Tools retired. Drop-in v3 REST fix you can ship in one afternoon. Every step, working code.
- Ecommerce Platforms
- Troubleshooting
ShipEngine vs RevAddress: USPS API Comparison for Developers
ShipEngine vs RevAddress for USPS shipping. Pricing tiers, API design, code samples, and when to pick each. Zero marketing fluff.
- Vendor Comparison
- Pricing
Shipping API Comparison 2026 — Pricing by Volume
Compare EasyPost, Shippo, ShipEngine, and RevAddress for USPS. Pricing, code samples, migration cost. 2026 numbers.
- Vendor Comparison
- Pricing
Shippo vs RevAddress: Which USPS API Is Right for You?
Head-to-head: Shippo vs RevAddress for USPS shipping. Pricing at every volume, architecture, code samples, when to pick each.
- Vendor Comparison
- Pricing
USPS API Pricing 2026 — What It Actually Costs
USPS address validation stopped being free on August 1, 2026. The published fee curve, the license that gates it, and what direct-vs-third-party actually costs at four volumes.
- Pricing
- USPS License
- Rate Limits
USPS API Rate Limits in 2026: From 6,000/min to 60/hour
USPS v3 throughput fell from roughly 6,000 requests per minute on Web Tools to 60 per hour. What changed, what it does to checkout at peak, and five architecture patterns with working code.
- Rate Limits
- USPS v3
- Troubleshooting
USPS Batch Address Validation — 50 per Call
Validate up to 50 US addresses in a single API call. Parallel processing, 24-hour cache, webhook results. Integration in minutes.
- Address Validation
- Rate Limits
USPS CRID and MID Enrollment: Complete Setup Guide for v3 API
Step-by-step USPS CRID registration, Mailer ID (MID) enrollment, EPA setup, COP claims linking, and the Addresses API license that has gated address validation since August 1, 2026.
- USPS Enrollment
- USPS License
- OAuth
- Troubleshooting
USPS v3 OAuth Troubleshooting: Every Error and How to Fix It
401s, 403s, or token refresh failures from USPS v3? This guide covers every OAuth error with fix recipes. CRID, MID, EPA setup.
- OAuth
- Troubleshooting
- USPS Enrollment
USPS v3 Address Validation in 30 Seconds
Validate a US address with the USPS v3 REST API in one curl command. Working code for Python, Node.js, and curl — no XML, no USERID, no middleman.
- Quickstart
- Address Validation
USPS Web Tools Migration Checklist (2026)
Step-by-step checklist for migrating from USPS Web Tools XML to the v3 REST API. OAuth, endpoint mapping, error handling.
- Web Tools Migration
- USPS v3
USPS Web Tools Shutdown 2026 — Migration Paths
USPS retired the Web Tools XML API on January 25, 2026. See what broke, which platforms were affected, and the fastest migration path to the v3 REST API.
- Web Tools Migration
- USPS v3
- Pricing
WooCommerce USPS Migration: From Web Tools to v3 REST API
Replace your broken WooCommerce USPS shipping plugin with RevAddress v3 REST in one afternoon. Every hook, working code.
- Ecommerce Platforms
- Web Tools Migration
EasyPost March 17 Enforcement: Migration Options After Auto-Enrollment
EasyPost plan enforcement is live. Compare migration options with exact cost savings at 1K-50K labels/mo, side-by-side code examples, and a 5-step migration checklist.
USPS v3 Migration Guide for Node.js & Python: From Web Tools XML to REST
Step-by-step migration from USPS Web Tools XML to v3 REST using the usps-v3 Python and Node.js SDKs. Side-by-side code comparison, OAuth setup, endpoint mapping, and testing checklist.
USPS April 2026 Access Control Changes: Why You Should Migrate Now, Not Later
USPS is restructuring API access control in April 2026 — the second wave of breaking changes. Timeline, what's changing, action items, and how to build an integration that survives both waves.
EasyPost March 17 Enforcement: What Happened If You Didn't Choose a Plan
EasyPost plan enforcement is live. Free Access vs BYOCA explained, cost impact at every volume tier, and flat-rate alternatives.
USPS API Access Control: What Changes in April 2026
USPS is launching its API Access Control initiative in April 2026, restricting tracking data access for service providers. What changes, who's affected, and how BYOK insulates you.
usps-api / usps-webtools Are Dead — Here's the 2026 Replacement
The usps-api PyPI package, usps-webtools, and usps-webtools-promise npm packages all target the retired USPS Web Tools XML API. They are broken. One-command migration to usps-v3.
USPS v3 SDK for Python, Node.js & PHP — Open Source, Production-Tested
Install the usps-v3 SDK for Python, Node.js, or PHP. Automatic OAuth, address validation, tracking routes, pricing, and managed USPS workflow support. MIT licensed with automatic token management.
USPS v3 API with Node.js: Complete Quickstart Guide
Install the usps-v3 Node.js SDK and start validating addresses, querying tracking routes, and running USPS label workflows in minutes. Full TypeScript support, zero dependencies.
USPS v3 API with PHP: Complete Quickstart Guide
Install the revaddress/usps-v3-php Composer package and start validating addresses, querying tracking routes, and running USPS label workflows. Magento, WooCommerce, and Laravel integration.
EasyPost vs RevAddress: USPS Shipping API Pricing Compared
Factual pricing comparison between EasyPost and RevAddress for USPS shipping APIs. Per-label vs flat pricing math, feature comparison, and when each wins.
USPS Web Tools to v3 REST API: Complete Endpoint Mapping
Definitive USPS Web Tools XML to v3 REST mapping across addresses, tracking, labels, pricing, and locations.
USPS v3 API with Python: Complete Quickstart Guide
Install the usps-v3 Python SDK and start validating addresses, tracking packages, and comparing shipping rates in minutes.
USPS Web Tools to v3 REST: Complete Migration Guide
Step-by-step guide to migrating from USPS Web Tools XML API to the new v3 REST API. Endpoint mapping, OAuth setup, rate limit handling, and code samples.
USPS API Rate Limits: How to Handle 60 req/hr in Production
Practical strategies for handling USPS v3 API rate limits. Caching, batching, queue architecture, and BYOK for production workloads.