Address Verification Concepts

Verification goes beyond validation - it confirms an address is real and deliverable.

Validation vs Verification

Verification Levels

Level 1: Format Valid

• Postal code matches country pattern
• Required fields present

Level 2: Components Valid

• Postal code exists in database
• State matches postal code region

Level 3: Address Verified

• Full address geocodes successfully
• High confidence match

Level 4: Deliverable

• Carrier confirms delivery possible
• No PO Box restrictions violated

Using Nominatim for Verification

Nominatim (OpenStreetMap) provides free geocoding:

javascript
1async function verifyAddress(address) {
2  const query = encodeURIComponent(
3    `${address.street}, ${address.city}, ${address.state} ${address.zip}`
4  );
5
6  const response = await fetch(
7    `https://nominatim.openstreetmap.org/search?q=${query}&format=json&addressdetails=1`
8  );
9
10  const results = await response.json();
11
12  if (results.length === 0) {
13    return { verified: false, error: 'ADDRESS_NOT_FOUND' };
14  }
15
16  return {
17    verified: true,
18    confidence: parseFloat(results[0].importance),
19    coordinates: {
20      lat: parseFloat(results[0].lat),
21      lng: parseFloat(results[0].lon)
22    }
23  };
24}

Confidence Scores

Geocoding APIs return confidence or importance scores:

Best Practices

1. Validate format first - Don't waste API calls on invalid formats
2. Cache results - Addresses don't change often
3. Use multiple providers - Fallback if primary fails
4. Set confidence thresholds - Reject low-confidence matches
5. Log verification failures - Track patterns for improvement