What should I use for address validation and normalization?

It depends on what you mean by “validation and normalization,” because those are usually two different jobs:

1) If you want to verify an address is real / deliverable

Use an address validation API that checks against postal data and can standardize the result.

Common options:

• Google Address Validation API — strong global coverage, good normalization
• Loqate — very strong international address verification
• Melissa — good validation, especially enterprise use cases
• Smarty — excellent for US addresses, easy to use
• Experian / Precisely / HERE — enterprise options

2) If you want to clean up formatting only

Use a normalization library or rules-based formatter:

• parse components
• standardize abbreviations
• canonicalize casing
• reformat to a consistent template

For example:

• 123 Main St Apt 4B
• 123 MAIN STREET #4B
• 123 Main Street, Unit 4B

can all be normalized to one standard format.

3) If you want both

Best practice is:

1. Parse the raw address
2. Validate it against a postal/reference database
3. Normalize the output to a standardized format
4. Store both:
   • original raw input
   • standardized/validated version

Quick recommendation

• US-only, small/medium app: Smarty or Google
• Global coverage: Loqate or Google
• Enterprise / data quality workflows: Melissa or Precisely

If you want, I can recommend the best option for your case based on:

• country/region coverage
• budget
• API vs batch processing
• need for geocoding or USPS/Canada Post/etc. certification