Smarty Address API
Smarty (formerly SmartyStreets) CASS-certified US address verification API — validate, standardize, and geocode US and international addresses with USPS delivery point validation.
Score Breakdown
⚙ Agent Friendliness
🔒 Security
Auth-ID/Token pair provides dual credential requirement. Embedded key feature for client-side use with referer restriction. TLS enforced. SOC2 Type II certified.
⚡ Reliability
Best When
You need USPS CASS-certified address validation with delivery point confirmation — highest confidence for mailing/shipping workflows.
Avoid When
You need global geocoding beyond address validation, or place search — Smarty is purpose-built for validation not discovery.
Use Cases
- • Real-time address validation at point of entry in agent-managed forms to reduce bad addresses
- • Batch address cleaning for existing databases — standardize and USPS-validate address lists
- • Delivery point validation (DPV) to confirm an address receives USPS mail before shipping
- • Address geocoding to lat/lng for US addresses with rooftop-level accuracy
- • International address validation across 240+ countries for global agent workflows
Not For
- • Place search or autocomplete — use Google Places or Mapbox for interactive search
- • IP geolocation — use IPinfo or MaxMind for IP-to-location
- • High-volume free geocoding — Smarty's free tier is limited; use Geocodio for budget batch geocoding
Interface
Authentication
Auth-ID and Auth-Token pair passed as query parameters or headers. Embedded key option for client-side use (browser-safe, restricted by referer). Server-side keys unrestricted.
Pricing
Pricing is per-lookup with volume tiers. International address validation is a premium add-on. Enterprise plans available.
Agent Metadata
Known Gotchas
- ⚠ Empty results array means address is invalid/undeliverable — not an error, but agents must check
- ⚠ USPS DPV footnotes (A1, BB, S1, etc.) encode specific validation failures — agents should parse these
- ⚠ Embedded key restricts by referer — server-side agents must use server key, not embedded key
- ⚠ Batch endpoint processes up to 100 addresses per call — agents must chunk large lists
- ⚠ International validation requires separate API endpoint and subscription — not included in US plan
Alternatives
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Scores are editorial opinions as of 2026-03-07.