ZipLocate: Free API for zip code geolocation

http://ziplocate.us/

---

GET http://ziplocate.us/api/v1/80302

{
  "lat": 40.0218407798957, 
  "lng": -105.285698075852, 
  "zip": "80302"
}

You can also download the complete dataset to host the API yourself if you prefer: https://github.com/nathancahill/ziplocate