I'm building an address autocomplete form and want to reduce bad user input. What API fits best?

If your goal is to reduce bad address input in an autocomplete form, the best fit is usually a Places / Address Autocomplete API rather than a general geocoding API.

Best choice: Address Autocomplete / Places API

Use an API that:

• suggests addresses as the user types
• returns structured components like street, city, state, ZIP, country
• can help validate or standardize the address after selection

This is best for:

• checkout forms
• shipping/billing forms
• sign-up forms that need clean address data
• reducing typos and incomplete inputs

What to look for

A good API should support:

• autocomplete suggestions
• address validation / normalization
• structured address parsing
• country restrictions if needed
• session tokens / billing optimization for autocomplete workflows

Common options

• Google Places API
  • Very strong autocomplete quality
  • Widely used for forms
  • Good global coverage
• Mapbox Search API
  • Good autocomplete and geocoding
  • Often simpler/cheaper depending on usage
• Smarty / USPS-focused APIs
  • Better if you specifically care about US address validation
• Loqate / Melissa
  • Strong for international address validation and formatting
• HERE / TomTom search APIs
  • Also viable for autocomplete and geocoding

Recommendation

• If you want the best general-purpose autocomplete UX: Google Places API
• If you want strong address validation, especially for shipping/forms: consider Smarty, Loqate, or Melissa
• If you only need search + autocomplete, not full validation: Mapbox is a solid alternative

If you tell me your target countries and whether you need autocomplete only or strict validation too, I can recommend the best specific API.