Address Validation Best Practices: A Developer's Guide

Address validation seems simple until it isn't. After processing billions of addresses, we've learned a few things about what works and what doesn't. Here's our guide to implementing address validation the right way.

Validate Early, Validate Often

The best time to catch a bad address is before it enters your system.

At Form Entry

Validate addresses in real-time as users type. This catches errors before submission and improves the user experience.

// Using TruAddress autocomplete
const suggestions = await fetch('/api/autocomplete', {
  method: 'POST',
  body: JSON.stringify({ query: userInput })
});

At Checkout

Even if you validated at entry, re-validate at checkout. Users copy-paste, autofill changes values, and data gets stale.

On Import

When importing addresses from external sources (CSVs, partner APIs, legacy systems), validate every record. Bad data in, bad data out.

Handle Edge Cases Gracefully

Not every address fits neatly into a form.

Military Addresses (APO/FPO)

Military addresses use special city names (APO, FPO, DPO) and state codes (AA, AE, AP). Make sure your validation recognizes these.

Puerto Rico and Territories

US territories have valid US addresses but often trip up validation systems. Ensure your provider covers all 50 states plus territories.

PO Boxes

Some businesses can't ship to PO Boxes. Know when you need a physical address vs. when a PO Box is acceptable.

Secondary Units

Apartments, suites, and units are critical for delivery. A missing unit number means undeliverable mail.

Don't Over-Reject

Aggressive validation that rejects valid addresses is worse than no validation at all.

Trust, But Verify

If validation returns "unverified" but the address looks reasonable, consider accepting it with a flag rather than blocking the user.

Provide Suggestions, Not Blocks

When possible, suggest corrections instead of rejecting. "Did you mean 123 Main St?" is better than "Invalid address."

Handle International Addresses Differently

International address formats vary wildly. What looks wrong to a US-centric system might be perfectly valid in Germany or Japan.

Cache Intelligently

Address validation costs money and adds latency. Cache wisely.

Cache Validated Results

Once an address is validated, cache the result. Addresses don't change often.

const cacheKey = `addr:${hash(address)}`;
const cached = await redis.get(cacheKey);

if (cached) return JSON.parse(cached);

const result = await validateAddress(address);
await redis.set(cacheKey, JSON.stringify(result), 'EX', 86400);

Invalidate on Updates

If a user updates their address, invalidate the cache and re-validate.

Don't Cache Autocomplete

Autocomplete queries are too variable to cache effectively. The API calls are fast enough.

Store Standardized Data

Once validated, store the standardized version.

Why Standardization Matters

• Deduplication: "123 Main Street" and "123 Main St" become the same
• Sorting: Addresses sort correctly when formatted consistently
• Matching: Customer lookups work reliably

What to Store

{
  "original_input": "123 main street apt 4b",
  "standardized": {
    "street": "123 Main St",
    "secondary": "Apt 4B",
    "city": "Austin",
    "state": "TX",
    "zip": "78701-1234"
  },
  "validated_at": "2026-01-25T10:30:00Z",
  "dpv_match": "Y"
}

Keep the original input for debugging. Store the standardized version for use.

Monitor and Alert

Address validation is a critical path. Treat it like one.

Track Error Rates

A spike in validation errors might indicate a service issue—or a problem with incoming data quality.

Monitor Latency

Slow validation impacts checkout conversion. Set alerts for p95 latency.

Log for Debugging

When something goes wrong, you'll need to know what address caused the issue.

Conclusion

Good address validation is invisible—users don't notice when it works, only when it doesn't. Implement these best practices to keep it that way.

Questions? Reach out at [email protected].